E-Thirteen Finally Answers the Age-Old Question:

Aug 27, 2014 at 16:01
by Richard Cunningham  
E-thirteen Inertia vs acceleration display 2014

E-thirteen built its rotational-inertia demonstrator to assure its wheel customers that the slight amount of additional weight of its Chubb hubs is easily offset by the use of a lighter-weight spokes and rims. Their science experiment, however, has greater ramifications.



Almost every cyclists insists that, if two wheels weigh the same, the one with the lighter rim and tire will accelerate faster - but where is the proof? Every wheel review worth reading either states or implies that there is a noticeable difference when accelerating a lighter or heavier wheel, but just how significant that effect may be, or whether it is largely a figment of the test rider's imagination has been cause for an endless round of debate. Add the wheel-diameter war to the equation and the discussion becomes less scientific and more emotional. Until now, however, the argument has been an intellectual one.

Because the tire is wheel's heaviest component, by nature, a 29er wheel should be the worst offender of the three diameters, yet the 29er's popularity among XC racers, where quick acceleration and climbing are of paramount importance, suggest that some of the advantages that big-wheel users espouse as scientific fact would be better classified as cycling religion. Evidently, e-thirteen has provided a definitive answer and, while the conclusion should not come as a surprise, when the results are physically demonstrated, arguments to the contrary are laughable.

Watch and Learn

Views: 173,950    Faves: 66    Comments: 28


E-thirteen, came to Eurobike 2014 with a simple science project, inspired by a hands-on display at the San Francisco Museum of Science and Industry. The experiment consists of two identical wheels of equal weight and diameter that roll down a steel track. The plastic wheels are weighted with brass cylinders. One with the cylinders positioned at the outer extreme of the wheel and a second, with the brass inserts positioned near the hub. If you don't want to bother watching the 15-second video, the wheel with the mass situated near the hub accelerates dramatically faster than the one which is configured in the opposite way.

Draw your own conclusions, but the results of e-thirteen's demonstration suggests that proponents of 26-inch wheels should not be discounted as the sport's angry villagers, reticent to accept any sort of change. The past two World Cup XC races were won on mid-sized wheels, which further undermines the once solidly held belief that big wheels are destined to rule that category. Perhaps the wheel debate deserves a less emotional and a more scientific re-evaluation.


456 Comments

  • 408 7
 Hey, remember that thing we always argue about, pointlessly? Yeah, let's argue about it some more!
  • 91 12
 I say we go back to the good old days and run 20 inch wheels
  • 233 1
 If I remember correctly, this 'age old question' was answered in my 11th grade physics class...
  • 46 0
 ^ I=mr^2. Whatever that means.
  • 70 1
 Yeah Science Bishhhhhhhhhh
  • 57 0
 By good old days, I think you mean the Penny Farthing Rollover in the front, playful in the back
  • 180 1
 I am going to add weights to my hub so I can accelerate faster! Thanks e13
  • 7 21
flag Aarrce (Aug 27, 2014 at 18:16) (Below Threshold)
 The best answer with any type wheel would have to by just heavy ass disc brakes disc.
  • 19 2
 Ahhhhh man that 27.5 koolaid was soooooo good, though! Why the hell you gotta bring "science" into it?!
  • 58 12
 I think what everyone here needs is a straight to the point physics 101 class from an engineer. I'm going to assume everyone here also has enough IQ's such that you know how to pump your tires up. Wink

The torque required to spin a wheel with a certain angular acceleration is equal to the cross product (multiplication for simple cases) of the desired angular acceleration and the moment of inertia. Angular acceleration is just a rotational form of linear velocity. the radius of the wheel multiplied by the angular acceleration is the linear velocity (bike speed).
The moment of inertia for a round object is just the total weight of that object (well, mass..) multiplied twice by the radius of the wheel. So, if you consider the torque you apply to the wheel as your effort or "how hard it is to pedal" and assume you want to accelerate at a certain rate, the ONLY way you can argue that a wheel accelerates faster is either that it is lighter, or has a smaller radius. By this we also see that the effort(torque) is way more dependent on the radius of the wheel than it's mass.

In laymans terms, the size of the wheel, has a ton more impact on how hard it is to accelerate that how much it weighs. 29ers are waaaay lighter than normal rims, and that's how they compensate for the added radius
  • 20 10
 TLDR ^
  • 16 156
flag dirteveryday (Aug 27, 2014 at 19:45) (Below Threshold)
 Bullitproof... you know engineers are at in the upper end of "most hated humans on the planet" right? Second only to first year and drop out psychologists...

"Works on paper...I don't see the problem..."

Lol...
  • 28 4
 Bullitproof......that math only applies to "free space" conditions. Take in real world scenarios such as the trail condition based resistance. Create a constant for that and compare wheel sizes at a given velocity. We know what wheel would win. I personally like the 26 inch wheel the best. I dont race or need to go fast at all. I granny gear the snot out of flats and climbs and push my limits on the downs. Just wish all these cool new bike had a 26 model.
  • 16 66
flag dirteveryday (Aug 27, 2014 at 19:53) (Below Threshold)
 And while I have never found a REASON to switch frames, forks, etc to increase my wheel size and an perfectly happy with 26" wheels... as a life long rock crawler I also understand a force most here are forgetting: inertia. Heavy wheels WILL continue to roll over and through terrain that will slow down a smaller wheel, while at the same time filling the holes between obstacles, which is more effective than rolling OVER the said obstacles. So I absolutely see the benefits of 29" wheels. What is absolutely retarded is this fruity bullshit "I can't decide" 27.2 size.

27.2...for trendy pussies who can't commit...

I should be in advertising... lol
  • 14 2
 Yea of course, but I do not believe that the start-stop acceleration factor can be felt without making 29er wheels extremely light to overcome their "clunky ness"
And @dirteveryday,
You should only hate on engineers that gradually increase tech, when they can just go to the top end products without any added effort. We are here to make things better, not extort the public.
  • 15 1
 @Bullitproof
In this case I think it would be better to put it as dω/dt x I = τ. This always holds true, regardless of the terrain. For a bike dω/dt = (dv/dt)/r, where r is the radius of the wheel. For a bike, all of this is purely linear so the cross product can be simplified to mr(dv/dt) = τ. Taking that a step further, the trail exerts some resistance on your wheel, which I will just call τ (it's really r x F_trail). So the equation for the amount of force you need to apply to the pedal can be written as mr(dv/dt) = τ-(r_crank x F).

Also, you said "the radius of the wheel multiplied by the angular acceleration is the linear velocity". This is false. That would equal the linear acceleration.

THE TAKE AWAY:
The force you need to make your bike accelerate a certain amount is directly proportional to the mass of the rim (because this is simplified) and the radius of the wheel. Decreasing wheel mass offsets increasing the radius. With 27.5" wheels, you would have to buy rims that are about 95% the weight of 26" rims to get the same acceleration.
  • 3 1
 Huh?Except that 29er wheels are not as a rule waay lighter than other rims. Some are but then so are some 650b and 26 inch rims...
  • 6 0
 Indeed they are not as a rule lighter. This is why wagon wheels are often sluggish. Unless you are going with carbon rims, wheel mass will increase with wheel diameter assuming you are looking at similar quality rims. Of course tires make a big difference too. If you run DH tires on a 27.5 it will obviously be more sluggish than a 27.5 with super thin slicks. So hey, if you drop $2k on wheels you can accelerate just as quick. Why doesn't everyone do that? haha
  • 3 52
flag hodakaracer96 (Aug 27, 2014 at 22:56) (Below Threshold)
 Richard Cunningham not sure if you have an agenda or are a douchbag or both. What a onesided and incomplete rightup (no mention of the other benefits of bigger wheels)
  • 35 2
 Hey guys lets insult the guy who can delete your account with the click of a button
  • 24 0
 @bderrics the answer to the age old question is 42, duh
  • 9 9
 This starts from a stand still we rarely ever start from a standstill out of a corner or anywhere on a trail. Also this example looks highly exaggerated which really skews how we perceive the advantage.
The weight is placed 2-3 times further out (200-300%), where when we talk wheel size from 26-29 we are only talking about a increase in 9%. This test unless I am mistaken is hugely exaggerated at least if we discuss wheel size.

As for the hub argument they are proving their point that more weight center to the wheel allowing a reduction in the outer weight is beneficial.

@taquitos and @bullitproof
Is there not a point where the more inertia from the larger wheel will promote faster acceleration at a specific speed and therefore we receive a cross over effect.

Really the question is, what wheel size is more effective for my average speed over the track. faster here and there means nothing its all about the overall time. Hence the 29er xc move.
  • 11 0
 slidways: is there not a point where the increased inertia of the larger wheel will promote faster accel. at a specific speed?

No. Bigger wheels at the same mass are always harder to accelerate.
  • 5 9
flag slidways (Aug 28, 2014 at 1:02) (Below Threshold)
 but there is a point where the inertia of the heavier wheel will make it easier for the rider to get to speed via less input, there is also a point where the heavier wheel will surpass the lighter wheels top speed. The close the lighter wheel reaches its maximum speed the slower it will accelerate, as will the heavier wheel but the heavier wheel will have a higher top speed so you get a point where the heavier wheel is accelerating faster. We cant discount inertia.
  • 2 0
 @taquitos

rims for each purpose (compare XC rim with XC rim, or DH with DH) would always be lighter in a smaller diameter.

Roval Traversee 29'er rim in aluminium alloy on my XC bike is 412 grammes, I only know because I stripped the wheel to rebuild with new spokes and nipples and was surprised how light the rim actually was for its size, its quite wide too.

I have not weighed any comparable 26" or 650b rims in this category recently

all my previous rims were FR / DH so obviously heavier even in the smaller 26" size
  • 8 0
 @wuzupjosh shhh, don't give companies any ideas.
  • 15 2
 They should've made that rail in a u-shape to show that heavier wheels carry speed better.
And yeah, it's essentially the same, but a lot of people don't seem to get that "carrying speed better" is just the same as "accelerating slower" (deceleration is just negative acceleration)
  • 16 1
 26" wheels look better Razz good enough for me Big Grin
  • 1 1
 *I meant bigger wheels my bad
  • 2 1
 hahaahahahaha commencal
  • 6 0
 So u're saying 26 is back a comeback? thanks E13
  • 20 3
 Nice to see some actual physics on here!

Just a reminder that the inertia thing cuts both ways. The same inertia that makes the 9er harder to get up to speed is going to make it retain speed better than a smaller wheel, and that's without even taking into account the rollover (angle of attack) characteristics of each size.

"yet the 29er's popularity among XC racers, where quick acceleration and climbing are of paramount importance, suggest that some of the advantages that big-wheel users espouse as scientific fact would be better classified as cycling religion."

This, like the whole article, is just pointless provocatuer shit. It's not that there's some 29er religion or that people haven't known all this LITERALLY SINCE THE FIRST DAY 29ERS APPEARED. The point is that XC racers have determined that the more difficult acceleration is an acceptable tradeoff for the rollover and traction advantages. And especially for bikes that are meant to be ridden on rough terrain, the rollover will have a much greater impact on overall efficiency and energy expenditure than the inertial mass of the wheel (to a point.... I don't expect XC 32" wheels to be a thing anytime soon).

Yes, many recent XC races have been won on smaller wheels, but this only reinforces the point that there is an optimal diameter (specific to the rider, probably) that balances the terrain-smoothing efficiency of a larger wheel with the snappy acceleration of a smaller one. That, along with bike geometry implications, will drive people's wheel choices. But XC racers won't be going to 26" or 24" wheels for snappy acceleration anytime soon, because acceleration isn't the only variable in the equation.
  • 7 6
 preach, brother bkm303. I think the "feeling" of improved acceleration that people get is actually the fact that you get more distance out of a single rotation of a bigger wheel: that improved distance covered per rotation translates into a "quicker" feel.

But I think the real advantages of bigger wheels is the improved geometry it allows: you're not going to get 15mm of BB drop on a 26" bike, you can usually steepen the head angle & reduce travel while still retaining the same level of descending ability, etc.
  • 2 3
 Jesus, this is still going on? @wuzupjosh was the only person with anything relevant to add.
  • 3 0
 It's not that simple because the distribution of mass and moment of inertia are represented by 2nd rank tensors here--not scalars.
  • 5 2
 @bkm303 there is no traction advantage with bigger wheels. The contact patch has the same area no matter what wheel size. The shape is different but not the area. Weight and PSI dictate the contact patch area. Big misconception with bigger wheels.
  • 8 2
 i like bikes
  • 6 4
 **for the same pressure** the contact patch is the same size, but since the volume of a 29" tire is larger than 26" there is no reason to run the same pressure. The added volume enables lower pressure (as long as you're not burping), which is where the traction advantage comes from.
  • 1 1
 Slidways- No, a heavier object will never accelerate faster than a lighter one with the same imput of power. Acceleration is a change of speed and inertia is the resistance to change speed.
  • 3 0
 If you're talking about angular acceleration, a lighter object CAN (angularly) accelerate faster than a more massive one, IFF it's moment of inertia is lower.
  • 9 1
 Bkm303 - thank you for a truly open minded insight, filled with perspective. Acceleration is indeed not always the main factor indeed but so isn't the roll over. I would say that it depends in the physiology of the rider just as it depends on the terrain. The size of the obstacle matters just as the amplitude of speeds. The grip is also a very blurry bit because it depends so much on knob pattern and rubber compound (just as rolling resistance). Pressure huh? One terrible selling, sorry buying point is that an average Joe thinks that he has all the bits sorted out: tyre choice, tyre pressure, suspension setup, (did we talk on diet?) and the only thing missing is "that new thing". So that new thing will just add speed. The problem is that everything is a matter of balance and that new thing may or may not bring things together.

After testing a few 29ers I can say one thing: if you want a fun bike not a freaking train wagon: you need carbon rims and light ust single ply tyres. Another thing I know about big wheels: roll over is bullshit - just let out some tyre pressure of your small wheels and tadaaaaa!
  • 9 2
 Im just gonna stick by the "pick your wheelsize and be a dick about it" approach to things
  • 3 1
 I stick to my usual: "you are probably delusional anyways", so you are wrong but it doesn't matter because at the same time you are right, so I will write anything that can propell the further discussion but in a way so I can say everything I wanted to say.
  • 4 0
 @waki I absolutely agree that you can get a similar rollover effect on a 26" by using a high volume tire at low pressures (and in fact my FS 100mm 26er rides WAY smoother than some 29ers I've ridden). But I definitely wouldn't say that rollover is bullshit. To achieve similar smoothness/rollover to the larger wheel, the smaller wheel will need bigger rubber, which will then increase diameter, mass, and moment of inertia, which will then cut into your acceleration advantage.... effectively making your 26er more 29erish. Like anything else it's all tradeoffs.

Yeah, getting a 29er spinning is slower than a 26er, but on a hardtail the acceleration and power transfer are so snappy that I don't notice too much. I've had an awesome time riding my roommate's 29er HT. And I love riding my CX bike on singletrack, which is more less a rigid 29er. I've yet to ride a 29er FS that didn't feel tippy and handle like a canoe though. For FS bikes I definitely prefer 26" or 27.5", especially cuz you can get similar "rollover" from the suspension and tires. Soon I hope to own a 27.5 hardtail though.... I think that would be my ideal bike. I've really liked the few 27.5 bikes I've tried.
  • 2 0
 Mission accomplished.
  • 3 1
 Correct me if I'm wrong, but this article isn't exactly addressing the 26" vs. 27.5" vs. 29" debate. It's stating that a wheel will accelerate faster if the mass is situating closer to the hub, versus positioned toward the outside of the wheel. Which is not unlike the flywheel mounted to the backend of your crankshaft, and also why, when applicable in race cars, the material is removed from the non-mating surface areas to decrease drag/increase acceleration.

www.sjbmw.com/_images/parts/28_lg.gif
  • 2 0
 Tight. This explains a lot about why my new--albeit heavier--wheels accelerate noticeably quicker. Heavy hubs and lightish rims are AOK. Big Grin
  • 3 2
 27.5 should only be available to true racers and pros. Us mere mortals should only be allowed 26" wheels for downhill.

#shutthef*ckupaboutwheelsizes
  • 4 0
 @loamydog when talking about acceleration, yes. but weight in wheels has another important consideration: It's unsprung. Wheels remain one of the best places to trim weight from your bike, but the closer you get to the edges, the more effect it has.
  • 1 0
 @grog hunter spot on ... people only thik sbout ho fast their bike accelerates when they think of this first hand , having a 26 inch wheel with the same gearing as a 29 `will accelerate faster with les effort because your strenth from your leg will be moving less , as opposed to a 29 where there is more mass and weight involved , ITS VERY COMPLICATED , and youd have to be super smart to figure it out , im not that smart lol but but its the same as going from 20 to 26 , i was building my dj and wanted a slightly harder gearing than my bmx, i used sheldon browns calculator and figured out 10x24 t gearing on my dj is 4.6 or so revolutions to 28x9 on the bmx, the bmx had 4.2 or so , but if i put the same gearing on my mtb "28x9 " on the 26 wheel is would be verrrry hard to pedal ....
  • 2 1
 Good stuff ^. Perhaps $1600 for carbon rims is worth it after all...
  • 1 0
 I'd wait for the Stan's rims to start retailing. if the wheels are $1900, It's possible that the rims will be sub $1600 for a pair.
  • 1 0
 @taquitos, thanks for the correction, just a typo on my part.. Wink
and yes the derivative form is actually the correct (mathematically) way to write these equations. there is no measure of velocity that we have (yes, bombshell) velocity is just the rate of change of position (acceleration, the rate of change of the rate of change of position)
  • 2 1
 @feeblesmith

yeah I guess acceleration was the wrong word. My point was that the heavier object might reach a given speed faster because it suffers more inertia and therefore less deceleration. So the time it takes to get back up to speed may actually be faster than that of a lighter wheel due to the improved inertia. We never ride stop start we are always rolling or have some momentum.

If the inertia of the heavier wheel results in less deceleration than the time ti takes to get back to speed X may be shorter than that of a smaller lighter wheel as it suffers more from deceleration. Once we add in bumps and uneven ground the argument that a larger wheel is better continues to grow.
  • 1 0
 For anyone worried about acceleration do you even squat...?!
  • 2 1
 no, @slidways, ( @KUNTHER you too!) the angle of attack difference between a 26 inch wheel and a 29 inch wheel is really negligible. heres a picture to prove what i am saying, this is a relatively large bump, so it should, in principal, show the largest difference in attack angle of the bump with the tangent line of the rim at the contact point.
www.bike-advisor.com/wp-content/uploads/2013/01/wheel_27_5_650B_1.jpg
the difference of less rolling resistance is scientifically correct, but is it effective? without tests, i say a ~1 degree change in attack angle does not constitute a better platform.


in response to the inertia comment, it is the LINEAR momentum of the bike that we are concerned about. when a bike impacts a bump, it produces a force that acts 90 degrees to the surface of the wheel (this is actually what makes wheels useful). this does not create any torque on the wheel, which does not affect its rotational speed. what you have to consider is the horizontal and vertical components of that perpendicular force. the vertical component will not interact with the horizontal motion of the bike, and gets stored as gravitational energy/dispersed by the dampers. the horizontal force will change the bikes velocity, regardless of magnitude. the size of the horizontal component is determined by the angle of attack (defined above in the link) that the bump creates with the wheel.

to take away:
slowing the wheel down has less of an effect on the linear velocity of the bike than the horizontal force acting on the bike as a whole (through the wheel). heres a nifty home experiment (for everyone, at your own risk): try skidding to a stop (a stoppage of the wheels angular momentum), and then hit a brick wall (a horizontal force) at the same speed. Salute
  • 3 1
 The ONLY thing this experiment describes is:
1) if given the SAME diameter round objects (both objects in video are the same diameter, the only difference is weight distribution),
2) and if ignoring opposing forces from the "trail" (the only opposing force demonstrated here is at or near the axis of objects, not friction at the radius due to the trail which is what most of us call rolling resistance, and air I guess, negligible)
3) and constant acceleration due to gravity (the linear and static track, not dynamic like trails, with bumps and more so infinitely long)...

Drum roll please: More weight toward the center of a object will accelerate that object more quickly laterally than if the if that same weight is positioned to the outside of an object of similar size and overall weight. Assuming the above^^^which this experiment represents. So to relate to bikes...if two 26" wheels that weight the same are rolling down a flat hill, the one with a higher mass density near the axis (light rim/ heavy hub) will ACCELERATE more quickly than the one with higher mass density near the rim (heavy rim/light hub).

A longer track with bumps and variable elevation would show that the outside weighted object would have a higher lateral speed and not decelerate at bumps and hills as quickly as the other.
  • 3 1
 @Bullitproof angle of attack depends on the height and shape of the obstacle, and it's pretty easy to calculate using a little geometry and calculus (derivative of the equation for a circle). I did some excel magic and uploaded the results. Here I've assumed a 2.3" tire for all rim sizes (559mm, 584mm, 622mm) and a square-edged obstacle.

www.pinkbike.com/photo/11354970

Angle of attack difference between 29" and 26" for a 6 cm obstacle is about 4 degrees (which isn't too far off from what's quoted in Giant's literature). More importantly, if you look at the cosine of that angle, which determines how much of the impact force will oppose your forward movement ("slow-down force") you can see there's a pretty big difference. Obviously if the object is much taller than a few cm you'll be lifting the front wheel or bunny hopping over it, so the difference will be less meaningful. But basically for objects in the 4-10 cm range the 29er or 650b will slow down a lot less than a 26" would.

Anyway, this is a lot more detail than this article requires, but I just wanted to show that rollover isn't some myth or something you can only "feel", you can actually calculate it.
  • 5 0
 @bkm303 - I did some cad drawings a while ago and I kind of discovered that the bigger the obstacle the less the size matters. And that comes together with my nose sense that while I am riding on the fireroad I feel the 29er rolling faster, while in a rockgarden I feel no difference at all. Make no mistake if I lived in big mountains where I climb anywhere between for 1h - 4h I'd buy a 29er right awayh, for the stability and feel of the front wheel while cornering, but here in western Sweden I do not think a 29er can work, too small speeds, too tight corners, too steep uphills. I say it because the average naive bloke tends to wish to know what is the fastest no matter the circumstances, where as all is a matter of adjustment and optimization.

Ah and the actual roll over (how much energy is lost by encountering an obstacle) depends also on tyre pressure and suspension quality (hardness, setup) Smile
  • 2 2
 Because I get negged let me explain what I mean by a heavier wheel may be faster.

Let's say;
26 wheel takes 5seconds to accelerate 10mph. (0.5/1mph)
29 wheel takes 7seconds to accelerate 10mph. (0.7/1mph)

The smaller lighter wheel will always accelerate faster, but if we are riding a trail doing 20mph and we hit and obstacle or corner and the wheels slow down.

26 slows down to 10mph

29 suffer less deceleration and slows down to 13mph.

Now to get back to 20mph the the 26 will take 5seconds. But the 29er will only take 4.9seconds. Hence faster. While the 26 has a fast acceleration rate, the time it takes to get back to speed is actually less for the larger wheel due to its other benefits. For riders the critical number is the overall not one isolated factor.

If it slowed down say to 12 it would take 0.6sec longer but than you need to consider that the bike is travelling 2mph faster in the section prior before acceleration which more than likely will off set this and reduce time overall.

My point is acceleration is a factor but it's part of the larger equation.
  • 1 1
 @groghunter: Stan's carbon rims for dh coming soon?
  • 1 1
 bkm303 (2 days ago)
>The same inertia that makes the 9er harder to get up to speed is going to make it retain speed better than a smaller wheel
>The point is that XC racers have determined that the more difficult acceleration is an acceptable tradeoff for the rollover and traction >advantages.

All the clue is in these words. That's all I wanted to write untill read that.
Well done, bkm303!

Look at the video: note how longER the second wheel rotates.
Ofcourse! Naturally! because of greater inertia caused by it's periferial weight.
Accelerates slower, rotates longer. Accelerates quicker, rotates shorter.

About rollover and traction - that just obviously: there is much more probability you fly over your habdlebar hittihg the border stone with 26" wheel than 29" wheel. (fork the same, bike the same)
Just try.
I personally have an isuue 2 time with 26": first time flipp over bars uncontrolled and fall down, the second - almost flipped, just controlled and not falling down.
On 29" - never flipp over the same border.
That's just one of the example of rollover.

So the acceleration is not the main goal. It's just a ONE OF.
Moreover, you need to accelerate-and-accelerate again and again on smaller wheels than on bigger!
Isn't it obvious ???
On the bigger wheels you accelerate slightly slower but when got accelerated you see the speed is becoming terryfying and you think: oh, shit, I need to slower down a little!
Isn't it ? I notice that every time riding.

I personally like both 26' and 29'
Just buy reliable 26 and as much reliable and light 29. Thats all.
  • 6 1
 @bikesutomizer - the test shows ONLY the acceleration. It does not show anything. Xc racers do not figure out much - they ride narrow bars, short stems and no dropper posts. They ride what they are told to ride. Jose Hermida was still at the top and even winning races with 26" wheels when most of the field changed to 29". In Xc the human factor is so dominating that the size does not matter for efficiency. You got your heart, lungs, legs and core right - you rule, no matter the manufacturer or the wheel size.

I have never ever went over the bars because of the wheel size, cockpit setup, frame geometry or suspension quality. I do not think anyone ever did. People fall because A they make mistakes, and B-sht happens. While 29e rmay save you from 2% of OTBs, it will punish you somerhwere else, like in corners. If you get your balance wrong in the corner on 26", then it is relatively saveable, slight countersteer, hip adjustment, weight shift - things can turn out ok. On a 29er, due to inertia and BB drop stability it is not as easy (given similar wheels, cockpit and frame/suspension design). Once set on certain course, the 29er will always have a mind of it's own, even the best one. That is particularly visible when you want to change your line on a wide trail, or avoid an obstacle. Short note here: I experienced 275 wheels to be much closer in that respect to 29er than to 26.
  • 1 3
 15 seconds of our lives we'll never get back...
  • 1 1
 @loamydog Sorry, we didn't discuss what kind of riding you were doing, the valor rims would probably be a bit undergunned for DH from what I remember. Not sure when the next rim in their carbon lineup is due, & if it's a Flow replacement.
  • 1 1
 @WAKIdesigns
> the test shows ONLY the acceleration.
Yep, and NOTHING MORE. Did I tell the contrary?
It was obvious without any "scientific" test-video-shows that higher weight accelerating slowly than lower weight whatever it could be: wheel or etc. But the same time lighter wheel stops ALSO FASTER than hevier. And this has much more meaning.
Acceleration is NOT THE MAIN GOAL, but just the ONE OF parameters.
Want to accelerate faster ? Shift to larger rear gear. You've got a damn 9-11 pcs of them for what, how do you think ?

>In Xc the human factor is so dominating that the size does not matter for efficiency.
Phuhahh! What are you talking about...This Just about nothing - finger in the sky.
And by that logic the DH crowd are just differrent bunch of the equaly acting subjects ????
They ride what are they told to ride: expensive suspension bikes, that bad on pedalling, with fat heavy tires, 3.5kg heavy forks.
That's it ? Smile
Man, let's talk about real parameters in comaprision. Otherwise it just a flooding non usable text.

Look at fresh videos on pinkbike: the same guys that done a slopstyle 2 weeks ago now running the DH rampage these days.
I'm pretty sure they could blast the XC trails as well.

Size of the wheel do matter.
And the "efficciency" is very wide definition. What is it is this case ?

If your goal to accelerate faster - go 26". But don't forget about you will slower faster also, and worse to rollover the obstacles.
But with 26" the bike is more compact and better controlled on the very cool corners.
That age common known obvious things. Anyone was absent at school riding bikes???
Same time, who cares obstacles when flying over ? Smile

The wheel size is objective measurable parameter. It IS in reality and one could measure and try it.
***One should/must choose the wheel size&tires, geometry for the given terrain/trail - that is the goal.
  • 2 1
 With all due respect, I do not care much for parameters, as the sole fact of possessing any wider knowledge in the subject makes it very hard for you to attain any serious riding skills, UNLESS you work in bicycle industry.

***So one who does not race at highest level may wish to take it easy. And remember that Should is a weapon invented by teachers and preachers, Musts are always optional, Mays are closest to reality Big Grin
  • 3 3
 I don't care about wheel size but seriously, I ride a 32lbs covert and am faster than all the yahoos I ride with and they all have 10k bikes, 29 and 27.5. The media tells you this crap is better. Your 5 second vs 4.9 seconds proves that. Nonsense to me. Heart and lungs baby waki is right on that. I have ridden them all, and really don't care... I do firmly belief that the industry created a new toy and is desperately trying to make you believe it's faster/better whatever. When the fact still remains the same: for 95% of us it really doesn't matter. You actually believing that 4.9 seconds vs 5 seconds is a bonifide reason to spend 10k is ludicrous. Just my thoughts. Everyone gets mad at the 26 for life crowd when the root of it is simple fear of being forced into a product they don't want and need.
  • 2 3
 @slidways
based on the argument you make,the logical conclusion would be for xc racers to make their bikes as heavy as possible, in order to make their bike retain speed better. this is obviously wrong.....
  • 3 1
 LOL at a 32lb bike being considered heavy.
  • 1 1
 @gabriel-mission9
No it's not. That is a ridiculous exaggeration. We are talking about the offset of wheels here and the trade off. You know that making a frame heavier would hurt the ride rather than help it.

In the argument for wheel size what I am saying is correct but don't blow that up and start exaggerating that and applying it to everything. Your focusing too much on one aspect and not the overall picture.
  • 1 1
 @WAKIdesigns
>With all due respect, I do not care much for parameters,
Much...how much ? That becomes obvious from your last posts. Bad luck.

>as the sole fact of possessing any wider knowledge in the subject makes it very hard for you to attain any serious riding skills, >UNLESS you work in bicycle industry.
It is only when one have very bad understanding and visualising skills.
Or, if you want, stop to be a user - become a producer. (designer, manufacturer)

I personally do not make anyone to possess deep knowledge here.
But there are a fundamental things anyone should know(even must). They just obvious and must not be perverted by bla bla bla even when this bla bla bla armed with the words about a deep knowledge.
Understanding a fundamentals( = be able to visualise) one then make a choice according to terrain or etc., go riding and then using his own natural means gets the skills. Then binding the fundamentals' sceleton with the skills one reach the goals.

>***So one who does not race at highest level may wish to take it easy.
If one take it too much easy, he rescue to crash. Very often from the second try, cause the first try often lead by the God Smile ))

One must not take it easy. But at the same time one should not be stu..rictly a user who just buy only THAT $1500 26" wheel "STRICTLY BEST FIT TO DH" as manufacturer suggests.
Again - stop to be a user, try to be designer. And you'll see many things.

Please, do not mess Teachers with preachers.
If we had no Teachers(means real teachers) we have no modern bikes.

...But for what is it all and what about ?
The hevier wheel will always accelerate slower, and so roll-on longer than lighter (in the simple words that everyone can imagine)
These are one of fundamentals nevermind what you MUST OR SHOULD OR MAY OR CAN think about it. I hope till the end of times.
Just know and use it.

***One should/must choose the wheel size&tires, geometry for the given terrain/trail - that is the goal.
  • 1 1
 Visualization skills, stop being a user become a designer - you made me giggle there Smile
  • 1 2
 @slidways
erm....no? i was infact looking at the bigger picture rather than just focussing on one small aspect. many people in this thread have made the statement that increased inertia will result in better maintenance of speed and you have been the strongest proponent of this stance. i merely applied this view to the whole bike rather than just the wheels in order to point out how flawed an argument it is. i exaggerated nothing, and calling that ridiculous is, well, ridiculous....
  • 1 1
 @WAKIdesigns
It was adressed for all.
Good luck to you being gigled only by this.
  • 2 1
 Ah ok... But you shot and missed in my case, because values you described make me believe that going so deep into parameters is bollocks. Knowledge is fine as a knowledge but one that can actually make use of it is the wise man. I will put to you personally that a rider like Brook McDonald or Josh Brycelabd do not know much about what you are talking about. They only know how to ride a bike fast. They put energy into learning this, not parameters. And to be more precise Should is a weapon of a relatively bad teacher. Should is a mean of saying may and adding sense of guilt and obligation to it, where as must is such a strong word that it may trigger person to turn on critical thinking. Baf teacher does not want that. Cheers!
  • 1 1
 "I did some cad drawings a while ago and I kind of discovered that the bigger the obstacle the less the size matters. And that comes together with my nose sense that while I am riding on the fireroad I feel the 29er rolling faster, while in a rockgarden I feel no difference at all."

Again, it depends how big you're talking. Mathematically, angle of attack is really straightforward to calculate, but it's really only relevant out to a certain obstacle size. For tiny obstacles (millimeters, for example) the difference is negligible and all the wheels roll over nicely. Then for things in the 1-4" range (roughly) the differences in AoA are pretty significant. Then obviously as you get out to the limiting case (obstacle height >/= wheel radius...a wall) they're all the same again. But beyond around 3-4" angle of attack is not so relevant, because while a 29er might technically roll over an 8" log better than a 26er, only an idiot would just go smashing into it. Same goes for the rock gardens in your example, at a certain point it becomes a matter of technique and not wheel size. Rollover will technically be better in the rock garden, but you'll suck at mountain biking if you rely on it Razz But fire roads and small chunks on trails are where the 29er shines, because of the small obstacles (as you've observed in real life). Which is also why the XC dudes like them, for the long semi-chunky pedaling sections where small efficiency gains are crucial and bike handling technique isn't the main factor.
  • 1 2
 @gabriel-mission9

I said you were looking at one factor with your statement of "that logic suggest xc riders should make their bikes heavier, which we know is not true", That statement is not looking at the whole picture. You focused on my argument of inertia and the advantage of the wheel size based on deceleration than applied it in a one directional argument that " if more weight is better, we should have heavier frames then if that's the case". The bigger picture you would not have said that because as you know in the big picture adding weight to the bike would not make it faster and you know that the argument of the larger wheel is not just down to its weight but its size. In the big picture for wheels though the increase size is beneficial in some instances. I don't think they will be faster for all tracks, it will be track dependent, at least until larger wheels becomes so popular that tracks are tailored to the larger size.

The argument you made was not looking at the big picture and you know that, you took one factor and applied it to suit your argument.
  • 2 0
 @WAKIdesigns
I really don't care who you are. But seems like you have had REALLY BAD teachers Smile )))))
Do you hate your school times ? Smile

I really can't understand why are you started to write to @me and what are you trying to prove ? Smile
Could you explain your goals in strait simple way without bla bla?

You are not agree with a simple natural thing that the hevier wheel accelerates slower but rotates longer ?
You are not agree larger diameter wheel "eats" THE SAME obstacles better than smaller ???

And after that all you call yourself a designer ? Huh, the designer, who are "not much into the parameters" ????!
OMG!!!
You made me giggling Smile I knew a bunch of such, oh, they always think about themselves as a BIG persons. Smile

Could you show us the WORKING READY REAL WHOLE bike of your DESIGN-without-much-into-the-parameters ?
Notice: the DESIGN-without-much-into-the-parameters - that's obligatory!

Or show me the bike of any company or designer-constructor that made without "much into the parameters".
Huhuhu Smile

By the way, the guys you pointed here all know about that fundamentals.
Because TO KNOW is to have experience.
And I KNOW what I wrtie about.

Now, the word MUST - as I always knew, has an obligatory meaning. Not you choose.
And SHOULD - is kind of an optional meaning, if you want something, you should....if not - shouldn't. You choose.
MAY has always the mirrored tweeny called "OR MAY NOT"

But that doodling is already bored me really. I like both wheel sizes really and moreover, I know the reason why they act like they do and why I LIKE IT!
Who don't want to know the reasons - let them don't. Their time will come.

I have a proposal for you: make me a full suspension frame of my design. The design will be based bsically on Mongoose Pinn'r but with some improvements/mods to have more versatility.
What could you say about that?
  • 1 0
 @groghunter: thanks for the follow up. I heard about the valor but thought I missed a flow ex carbon or somethin haha...soon hopefully.
  • 173 0
 It might be a good idea to stay off pinkbike for a few days until this blows over.
  • 61 3
 Very relevant username...
  • 17 3
 Sorry JacobSkucki meant too +1 you and my fat finger decided otherwise.
  • 18 0
 I hope he will survive
  • 14 1
 DhGabe I got you covered!
  • 2 1
 just go ride yo bike
  • 112 6
 car A has a faster acceleration but lower top speed. car B has a slower acceleration but a faster top speed. banana.
  • 45 0
 Go Banana!
  • 15 0
 The apple would win.
  • 74 7
 Star wars is better than star trek
  • 28 2
 Maybe the original 3, everything else can suck it.
  • 48 2
 My dad collects coins
  • 34 0
 I bought a fish tank the other day
  • 21 0
 Proper oral hygiene dictates you should brush at least twice a day.
  • 3 0
 That woulf depend on thr length of the race course....
  • 10 0
 I like trains
  • 38 1
 If a duck came out of the toaster I'm afraid of goats
  • 2 0
 I'm a banana!
  • 10 0
 prove can't wrong
  • 61 1
 If guns don't kill people, people kill people, does that mean that toasters don't toast toast, toast toast toast?
  • 9 2
 Bacon!!!
  • 2 2
 Green eggs and ham
  • 27 0
 If you happen to see a turtle on a fence post somebody probably put it there
  • 2 1
 My bike is black.
  • 2 7
flag Rider656 (Aug 27, 2014 at 21:31) (Below Threshold)
 My ... is black!
  • 15 1
 I love lamp.
  • 4 1
 I see that you hear that im smelling a flying chicken
  • 1 0
 What's faster? The tortoise or the hare?
  • 8 0
 Peanut butter jelly time
  • 3 2
 proof the apple beats the Banana

www.youtube.com/watch?v=7m1h0Hf5uMs
  • 4 2
 well this escalated quickly .
  • 1 1
 I like turtles.
  • 6 1
 There is no spoon.
  • 2 1
 I measure my life in coffee spoons
  • 1 1
 Over the mountain is faster than on foot.
  • 2 1
 Im never satisfied... its a curse
  • 1 2
 bacon tastes gooood
  • 4 1
 the clown has no penis
  • 3 1
 My favourite colour is ham.
  • 3 1
 I don't eat no ham and eggs
  • 2 1
 Does anyone sell pre dug holes
  • 1 2
 Is it safe?
  • 2 1
 wear protection
  • 2 1
 My spoon is too big.
  • 2 1
 the human torch was denied a bank loan
  • 4 1
 The cake is a lie.
  • 3 5
 Fuck her right in the pussy!
  • 2 0
 Its the Unicorn from Uranus's fault.
  • 62 4
 So, E-13 (or any of you here who have a thesis coming up and are want of ideas), can you please extend that steel track. The internet would apparently need to see what would happen when the track you have....

a) flattens out and then
b) includes a small "bump" in the track over which the weighted discs roll

otherwise the lambasting will likely continue.
  • 34 2
 Nice suggestion, orientdave.^^^ That would be a great followup experiment.
  • 13 3
 Or, make the weight proportionally higher or lower to represent the proportional of Baby Bear, Mama Bear, and Papa Bear wheel sizes. You know, like the real thing this terrible experiment is supposed to represent.
  • 1 2
 I was also going to recommend that the wheels not be spinning on their spindles on a track, and maybe down a machined channel to get a more accurate resistance of the ground surface to wheel surface. The basic acceleration principles are one thing, but dont really prove anything. If said 26"wheels are lighter, dont use two examples of the same weight... use a lighter example and a heavier one. The perfect test would be to get 3 pro riders, get them to ride the tracks at the same time of day on the same lines on the 3 different wheel sizes on the exact same bikes. (clearly this isn't possible either, but i hope you get where im going with this.)
  • 8 5
 The above video is utterly pointless as frictional rolling resistance isn't taken into effect.

The rougher the track the bigger the 29" advantage.

Pointing out that Nino won the last two World Cups? Sure he's the best XC rider in the world so what a surprise that is! Oh and by the way, Absalon won the overall, on a 29".
  • 4 1
 Yes, but Nino completely missed 1 race. Got 0 points for it, and wasn't far behind first in terms of points
  • 2 1
 I know. Nino is incredible. I'm just pointing out the sensationalist crap in the article.
  • 5 0
 Well, there's a few pros and cons to each wheel size, the one you pointed out isn't the purpose of the article. Lets just agree that this turned into a huge clusterf*ck, and every wheel has its place?
  • 4 0
 I'll accept that there is no point to this article apart from increasing server traffic.
  • 4 1
 Looks like the wheel with the outer weights is doing a gyroscopic effect and losing traction on the smooth steel bars.
  • 1 0
 ^This.
  • 4 4
 The main problem with above video (I think) is that the "wheels" aren't travelling along the surface on their outer edge! The smaller one may increase RPM more quickly but in the world of bike wheels it needs to, because it's if you view it as a bike wheel then it will cover less distance across the ground per revolution.

29 wheels may accelerate slower, but they don't need to get to as high an RPM - a 29er at 20km/hr is going to have wheels which are rotating at a lower RPM than the equivalent 26' bike. Does this balance out though? Dunno.
  • 3 1
 isn't this primarily to support their new hub that is heavier but allows a reduction in rim and spoke weight?
While the weights need to be off set obviously you cant have 100 gram hub and only ave 10grams at the rim, if the saving is comparable this just shows that having central weight is better.

As for the wheel debate factor, its massively skewed. the weights are placed about 3times (300%) the distance apart, when in reality a size change from 26 to 29 is only about a 9% increase. Really they need a to scale wheel set up with realistically placed weight.
  • 2 1
 This article is pretty laughable. There are many variables that affect wheel performance. Weight is obviously important, and reciprocating weight is important more so. Wheels also need to address traction, stiffness, air volume, rolling resistance, and gyroscopic effect.

Has no one learned that a good trait is good in balance with other traits? EVERYTHING is a trade off. No one rides 24" wheels to get extra maneuverability at the WC level do they? It trades off too much. In DH 29" wheels trade off too much on the other end. That leaves 26 and 27.5" wheels. It seems the teams and the market are speaking very loudly.
  • 2 1
 Better yet, forget 26inch wheels then, lets rip on BMXs if faster acceleration were the only variable!
  • 1 0
 Good idea Orientdave. I'd also like to see an equal cylindrical housing on the two projectiles or the weights placed internally. That would even out wind resistance to a large extent..
  • 1 0
 Way to bring everyone back on topic! That was a pretty fun trip down memory lane.
  • 1 0
 Frictional rolling resistance is highly negligible, especially for a macroscopic demo like this. You'd need extremely sensitive instruments to quantify the effects of surface interactions on angular velocity. Lol
  • 1 0
 *acceleration
  • 1 0
 @orientdave
Man, it's not as much needed if just to notice how longer rolls-out the wheel with the masses on the periferial.
It is stopping much longer, noticably longer without any additional means Smile
And one who has a brain can think and imagine the futher results of it.

But you are rightly have set your question! Espacially for blah-blah-ers who just flooding here.


@Willie1
>It seems the teams and the market are speaking very loudly
Oh, man, how you're right!!!
  • 63 3
 this just keeps going round and round
  • 45 2
 I'm wheelie tired of it already
  • 33 2
 I already spoke to these guys about it honestly.
  • 32 2
 This topic is really the hub of some gripping debates
  • 37 4
 True
  • 28 2
 Just can't keep my bearings within this debate
  • 14 1
 Boring subject, but better than watching the tube.
  • 12 1
 I hope it doesn't spin out of control then
  • 4 36
flag metong (Aug 27, 2014 at 17:44) (Below Threshold)
 All of these just keeps on going round and round
  • 36 3
 These puns are making my nipples really firm.
  • 4 10
flag munro3 (Aug 27, 2014 at 21:15) (Below Threshold)
 These engineers are constantly pedalling new ways of thinking - I can't handle it! Sometimes I just want to tell the engineers and advertisers to get a grip. Seriously, though; the debate over 26" ad 29" wheels has single handedly forked the mountain bike community I half. I think it's time that we got back to our mountain biking roots by cranking up the music and taking a brake from the 26" VS 29" debate.
  • 7 1
 I'd rather give myself a rimjob
  • 3 1
 I think e13 is really getting traction in the debate.
  • 5 0
 Time for this conversation to get PUNctured
  • 1 5
flag TheBigManDH (Aug 28, 2014 at 2:09) (Below Threshold)
 I think people just need to get a grip
  • 2 1
 These puns are going in circles.
  • 2 1
 Ike and Tina Turner settled this debate years ago....
  • 1 2
 I think its time we put the brakes on this conversation. Disc has gone far enough
  • 1 1
 I'm tire of this
  • 1 1
 we should rotate the pun schedule. so people can get to grips with it. and it wont run flat
  • 1 1
 LOUD NOISES
  • 43 3
 Its because the bicycle industry is stuck in the "throw shit at the wall and see what sticks" business structure.....ALL you customers are the wall......
  • 5 2
 its an industry driven by demand. believe it or not, there is not alot of money around for bike R & D
  • 5 0
 Is that the throbbing I feel?
  • 7 0
 Not a lot of money for R&D? Tell that to the the big S or Giant, or Trek with their fancy F1 suspension "technology".
  • 4 3
 Bizutch No that's all the bike company's sticking it to you. Making you think that you just have to have the latest greatest thing they came up with. During a late night bong session...
  • 12 0
 what's with the dot dot dot? Don't leave me hanging. What happens at the session?
  • 2 0
 "there is not alot of money around for bike R & D"

That's what I've been wondering lately, so many new "OmG BeSt ReVoLuTiOn EvEr!!!!111!" stuff but it's mostly slight variations of pre-existing products or moto rip offs. Cassettes with a few extra teeth, handlebars a little wider, slightly bigger wheels, parts a tad lighter, barely noticable damper performance increase, different chainring teeth configuration...

Where's the true innovation? Are bikes really that perfect (hello drivetrains...) or is marketing getting the biggest slice of the budget?
  • 34 2
 They should try this with actual bike wheels.
  • 2 0
 I agree or use a sensor to monitor the actual rpms.
  • 3 0
 If they done it with bike wheels the difference would be so minimal that you would need a mile to see the difference , and that isn't as impressive as this demonstration and probably won't leave us buying their wheels. There is such an extreme in weight bias from hub to rim in this demo it's laughable.
  • 22 2
 i didn't think that this was even an argument. some grade 7 physics would teach....oh wait, we're in North America, everyone is scared of science
  • 13 0
 They're scared of science in Canada too??? Damn... I thought there was at least some hope.
  • 10 0
 nope, no hopeSmile
  • 1 0
 Frown

Mexico? Care to chime in on science down there?
  • 1 0
 i'd rather not
  • 24 4
 26" wheels are about to make a comeback !
  • 8 10
 Bwahahahahahahahahahaha!!!!!!!!!!!!!!!!!!!
  • 10 0
 And 29er dh bikes are around the corner... in the bushes.
  • 18 4
 What they should have done is used a smaller wheel to represent the 26 and a larger wheel to represent the 29 both with the weight to the outside. The 29er should have slightly more weight than the 26er. As the article states:

"Because the tire is wheel's heaviest component, by nature, a 29er wheel should be the worst offender " So thus a larger wheel would be slightly heavier.

But in this example the weight is to the center of the 1st wheel which would indicate that the hub and not the tire is the heaviest part of the wheel. So therefor I dont see how this experiment would conclude that a larger diameter wheel rolls slower.

The experiment rather suggests that if you can lose weight at the rim and tire thus forcing the hub to contain the most weight; you would then get faster roll. Which makes sense as if you look at the amount of force required to push the weight round a larger circle versus a smaller one.
  • 1 3
 I was wondering when someone with some sense would chime in here. Same thing I thought.
  • 2 2
 You should teach science.
  • 3 2
 I'm more buggered by the fact they're standing in a room full of bike wheels of all dimensions, yet they've built a "representation"?
  • 6 2
 This is really an experiment on Richard's part to stir the sh-- on a slow Tuesday, recognizing that his saying that this has anything at all to do with wheel size would make him Lord of the Thirteen-year-old flies.
  • 2 1
 Latham, ,et al...their demonstration was just a dramatization of how their hubs (CHUB)might be larger than other hubs, but that they are not hampering acceleration.

But to your point, just building up two wheels, one with their hub and a generic brand, would evidence an actual accurate display of their "thesis".
  • 6 1
 I think you missed the point completely.
They built a neutral setup - the plastic or whatever wheels of the same size and weight - added equal mass to both wheels with one representing a more spaced weight distribution from the center of mass and of rotation and another representing a closer spacing.
Thus showing that with wheels of equal mass the inertia is hugely different for different radial distribution.

For a true comparison of the different wheel sizes other experiences/demonstrations would be needed taking into account the different angular speeds the wheels have for the same linear displacement on the ground.
  • 8 1
 This is exactly it. People are missing the point here. This experiment was not meant to be a 26" vs 29" inch wheel comparison. It was simply a theoretical experiment (which uses very exaggerated weight biases ) to highlight how the distribution of weight around a wheel effects acceleration, nothing more.
  • 2 0
 What if you roll through dog poop and it sticks to very little of a 29" shallow knobbed tire versus the same poop sticking to a Specialized Butcher (aggressive knob) on a 26" wheel?

What then?
  • 1 1
 @bizutch the 29er has a bigger contact patch so more poop could stick to it thus making the outside of the wheel heavier, so even slower acceleration on the 29er but it would keep more momentum. Also the 26" wheels have faster acceleration so better poop flinging ability and it swings the poop farther away at the very least.

So the take home lesson is buy a marsh guard.
  • 14 4
 The other side of the coin... The larger wheels will carry speed better due to more rotational inertia. Harder to get going, but once you have them going easier to keep them going.... I imagine and XC track with lots of tight corners and braking would be where the 26er would be faster....
  • 6 2
 Add rocks and other obstacles that bigger wheels roll over better than 26" and you cloud the debate a little more.
  • 14 2
 Your argument is invalid because it assumes a flat plane. XC has a variable that everyone chooses to ignore. No XC is ever won on the downhill. Pushing a bigger wheel uphill has gravity negating inertia unless it is on a single specific piece of terrain that the spacing of the obstacles is such that the lower initial contact between the obstacle and wheel path is so greatly reduced as to negate gravity.

Ride what you want to ride. All I ask if that the if bike companies produce 27.5 & 29" bikes, please keep making 26" wheels because Pisgah National Forest is one tight, twisty unforgiving mistress who rewards me and my short wheelbase and itty bitty wheels for my efforts. Big Grin
  • 9 1
 not only that but "rolling over better " is argument that just doesnt stick with me...If I find myself wishing to go faster, I lay of the brakes and if that isnt enough , I try to GENERATE or create more speed by working the ground.A smaller wheels will dive into those dips and big holes , back side of a rock or a root , allowing the rider to pump, load, thus help create speed where the bigger will simply roll over and more or less carry the same speed.Ask any experience riders and they will all agree it is far more difficult to generate speed , than carrying it.

Look at BMX's...they come in a bunch of different wheels sizes, yet at the end of the day, the pro racing is being done on the smaller wheel size. I now have bigger wheels on my bike and Im pretty much guarantee it just a placebo effect... As much I want it to be quicker, it does feels smoother but yet ,some of the same people Ive been riding with for years are still on smaller wheels and they are still on my ass ;-)
  • 3 2
 Its not invalid, it's not trying to prove what's faster/quicker over a long distance or varied terrain, its specifically about acceleration: " ,,,the wheel with the mass situated near the hub accelerates dramatically faster than the one which is configured in the opposite way."
  • 2 0
 The most recent UCI World Cup XC races were won by Schurter, and commentators suggested he won them on the downhill sections of the courses. Absalon , who came in second both times, agreed he was slower on the downhill and maybe that's where he lost the time. To throw another spanner into the debate, they were on different wheel sizes and Schuster rode a rear suspension bike. I only know this because I watch Red Bull TV, and I have absolutely no scientific evidence that shows XC races sometimes are won on a downhill. 29? 27.5? 26? Full suspension v. lighter weight? Jeez....
  • 2 0
 Sorry, that should read Schurter
  • 16 1
 Yeah 29" roll better over stuff, that must be why they always ride around the rocks and roots..
  • 1 1
 It's not a question of maybe, Schurter WAS for sure putting gaps on Absalon during the descents that had to made back up on climbing in the last 3 races. That was NOT a good situation for Absalon at all, or anyone else in that position. I bet Nino's smaller wheels handled a lil nicer too in those tighter sections.
  • 2 0
 freerabit, lol I think that's just an XC rider trait more than a wheel size concern. Maybe they can ride around the rocks faster on 29?
  • 5 1
 No, the 29" wheel keeps their crap riding skills from letting the wheel drop into holes and flipping them like drunken turtles...
  • 1 0
 Ya know, this ‘debate’ would probably be a lot more productive if riders who've only owned one wheel size would just stfu. Each size offers clear advantages.
  • 2 0
 Clear? Clear you say? What about chipmunks fella? There's no advantage to them. They've gotta dodge big wheels, small wheels, coyotes, douchebag foxes....pissy kids named Bryce.
  • 1 0
 There's a bloke who needs a haircut.. Hey Bryce, the 70's called, they want there hairstyle back
  • 20 6
 So does this prove 29ers are gay?
  • 12 4
 Yup.
  • 4 0
 i knew it!
  • 12 2
 EThirteen's experiment was to demonstrate the difference in HUB weight, not the difference in wheel sizes.

"E-thirteen built its rotational-inertia demonstrator to assure its wheel customers that the slight amount of additional weight of its Chubb hubs is easily offset by the use of a lighter-weight spokes and rims."
  • 6 2
 I'm glad someone else actually read the article.
  • 1 0
 Thank you for bringing this up. The E-13 demonstration has little if anything to do with wheel size. It is meant to display the importance of where the weight is located on a wheel.

RC, I like your articles but you just took this demonstration, which could have inspired some interesting points of view from the arm chair engineers, and simply used it to revive the endless 26/650B/29 debate.
  • 12 1
 Got my popcorn. Ready to sit back and enjoy the show...
  • 10 2
 Still rocking 2 26" wheeled bikes and loving it, smashed the 29ers on the tight technical singletrack at the brighton big dog last week, just my fitness letting me down on the climbs not wheel size :-)
  • 16 9
 am i missing something here? this has nothing to do with wheels size. in the experiment above the plastic wheels are the SAME size!
this isnt a 26, 275 or 29er issue, its a weight distribution experiment. PB you f'ed up here
  • 10 1
 26, 27.5, and 29 have different weight distribution.... the mass of the circle itself is pretty negligible in this example
  • 10 2
 So if you put the mass farther out, on a larger-diameter wheel of equal weight, it would change the results of the experiment? In this case, the suggestion is revelant. The results will be the same, for the same reasons.
  • 5 0
 The greatest element of weight in a wheel is the tyre and rim combination.

The brass weights on the plastic discs show the effect of having weight closer in to (aka smaller wheel size) or further away from (aka larger wheel size) the hub.
  • 4 1
 In this experiment, the axles have the same diameter, so at the same speed, both wheels have the same rotational velocity. With a bigger wheel, the wheel have less rotational velocity. so the "linear" inertia of big wheel, with the same weight in the tires, is ridiculous.
The big wheel have more inertia, mainly because the big tires are heavier. nothing related with this experiment.
The only thing shown here is the impact of mass distibution.
  • 4 2
 Yeah, the experiment doesn't show what they claim it shows. For two wheels of equal size (which these are because the axle rolling on the bar are the same size) the one with weight closer to the center will accelerate more quickly. The issue is that 29 inch wheels do not need to rotate as quickly in order to have the same linear speed as smaller wheels. This effectively cancels out the inertia issue - for two wheels that weigh the same.
  • 3 3
 jeez you guys size of the plastic wheels means squat. It weights placement which simulate having a larger wheel or smaller wheel. Its basic science...
  • 2 1
 so honestly...is the 100g difference between a 26 tire and 27.5 make that much of a difference because i run 2 bikes: on is a 27.5, one is a 26. Wheelsets, tires, and cassettes are the same. I don't really feel a difference at all
  • 1 0
 @Reelchef67. No the wheel is the part that is contacting the ground, in this case the axel. The weight is just changing the distribution of weight that the wheel has. Which rolls farther in one revolution a 29 inch wheel or a 26 inch wheel? A 29 inch wheel will roll 91 inches in a single turn. A 26 inch wheel will roll 82 inches. So a 26 inch wheel will have to spin about 9% faster to go the same distance. How much difference is there in mass distribution for the two sizes? About 9%. So while it is harder to spin up a 29er to the same rpm (which is what this demo almost, but not quite shows), it is NOT harder to spin up a 29 inch wheel and a 26 inch wheel to the same lateral speed (which is what we actually do on our bikes). Again this is for an everything else the same scenario between the wheels.

What people in the 26er camp should be arguing is that you can get a lighter stiffer wheel in 26 for much less money and that to get a wheel that is just as stiff and light and therefore accelerates the same will cost prohibitively more. Or that the roll over benefit (A comparison of which would be the difference in slopes of a line drawn tangentially through a point of impact from objects of equal height on the two wheels) is not enough to offset that lowered cornering ability of the longer wheel base, or something else that is actually physically true. Not acceleration.
  • 3 1
 No really ? Weight distribution is the all important everything, you are missing the point. A larger wheel has the weight distributed farther from the axle which means it will be slower to spin up. There is no disputing that.
Take a rock tie it to rope and spin it in a circle. now shorten the string by half it will spin easier and faster.
Acceleration is the speed of change not the speed. We constantly speed up and slow down. This is what they are showing.
Once you put tires,gearing, etc in the mix it much more complex. However you can't dispute basic laws of physics.
  • 1 0
 I am not disagreeing with the laws of physics, but the conclusions being drawn from them. You don't spin up wheels. You accelerate the bike and you. For a small wheel to large wheel comparison accelerating to an equal lateral speed (which is what we are talking about here - how much energy does it take to get a 26er going to 5 mph vs. a 29er to 5mph) we are not accelerating the wheels to the same rpm. The 29 inch wheel only has to spin 90% as fast as the 26 inch wheel to get the same lateral speed. So while the 26 inch wheel has about 10% easier spin up, it loses that advantage from having to spin faster to get to the same speed. It also important to note that we are only talking wheel weight here. So five pounds of my accelerated mass is in the wheels, 215 pounds is me, my gear, and the rest of the bike. We are talking about moving maybe 2/3rds of that five pounds, let's say 3 pounds, 10% farther from the axel. So if we pretend that somehow the wheels do have the same rotational velocity when going the same lateral speed (sure what the heck throw a 1" wheel on one end of a fixed axel and see how that works out), the large wheeled bike would feel like it had 3.3 pounds at the rims while the 26 would feel like it had 3 pounds. So it would be the difference of accelerating 220 pounds vs 220.3 pounds. I change weight by a couple pounds over the course of a ride. So wheel size acceleration issues? Meh.
  • 10 0
 Remember when people just rode bikes to have fun?
  • 11 1
 26 aint dead !!!!
  • 8 1
 Neither is science....
  • 11 1
 SCIENCE BITCHES!!!
  • 7 2
 OMG they are missing the most important piece, what happens when you stick a baseball card in your spokes! I dunno about you guys but when I have the card in the spokes, I accelerate so fast, and my momentum never slows because of topps' gravity and physics defying flapping action I skip right over all the wheel size debate bullshit!
  • 9 1
 And now 24" is gonna make a comeback...
  • 1 2
 Yes I'll have use for my single speed mag30 on the ole morphine if that's the case!!!
  • 5 1
 Why would this be such a revelation? Anyone with any kind of high school science knows how inertia and centrifugal force works.... Hell. Any 10 year old who's taken off a wheel and spins it holding the axles knows too... sure a 26 accelerates faster. But how does it manage impacts compared to a 29 or 650b? There's the science exhibit I'd like to see
  • 2 0
 Manages them well enough to win last years EWS, World Cup Eliminator (or was that 2012?), last years DH WC, half of the EWS this year. Ultimately I think it's the legs and skill at that level over wheelsizes. However, I've ridden all three sizes. I like them all:-D
  • 1 0
 And yet some people here still want to dispute it. More than a few "dull tools in the shop" need to go back to grade 7 science class....
  • 5 0
 'inspired by a hands-on display at the San Francisco Museum of Science and Industry"

Uhhh... there's no "Museum of Science and Industry" in San Francisco. Probably they were drunk.
  • 4 0
 Instead of an 'experiment' designed from the start to get a result the manufacturer wanted- remember this was to show you buying their heavier hubs wouldn't effect you. If you want to apply this experiment to wheel size debate. The wheels need to be different sizes, same weight, with the weight in the form of a solid ring around the outside.
  • 7 2
 It's not complicated, it's just moments of Inertia. Both weight and distance from the centre point determine the moment of inertia, aka, the resistance to acceleration
  • 2 1
 It's not complicated? The teenage me has different memories!

I distincly remember feelings of dread verging on suicidal tendencies when, way back in the day, the word "moment" re-appeared on my A level maths room's blackboard. All those coins spinning off LPs at 33 and 45 (told you it was back in the day), friction co-efficients of vinyl and ...aaaagrghrh. It used to do my noggin and still does, since I never really understood why you would NEED to know at what point from the centre of the said record your variously weighted coins would spin off.

Had they used examples of MTB wheels of different sizes I would probably have instantly understood it!!! Take note teachers of the world, make it real.
  • 4 1
 I saw this experiment in highschool...How is this a debate at all? Its not, only the ignorant debate a well validated scientific principle. PB, please, just stop - you are only contributing to the massive public confusion out there. I implore people to just do a little research:
en.wikipedia.org/wiki/Moment_of_inertia
  • 4 1
 It's just amazing seing people debating on this non-sense debate.
This is a physical law, and it's not new. In fact, this is an ultra-basic law of physics. It's known as "2nd law of motion" by Isaac Newton (around 1687). Sum of forces = mass * acceleration (in a translation movement) or in our case : Sum of Torques = Inertia * Angular acceleration.
If the repartition of the mass on your wheel is increasing inertia, you have less "angular acceleration" for the same torque. In other terms, if you push by the same amount of force on your pedals, your bike is reacting slower if you have more inertia and you will take more time to reach a given speed (but also take longer to stop).
End of story.
So you can have 26", 27,5", 29" or even 20", it's not a question of size, but a question of mass repartition. (that's for the "reactivity criteria"). This experience is only demonstrating that fact.
Now, for the maniability, it seems quite obvious that the smaller, the better.
And finally for the stability of your bike, it's not a question of wheel size, it's about the distance between the two points of contacts (wheelbase).
Now in real life, it's obvious that architecture of wheels directly impact on their inertia, and usualy, a 29" wheel will have more inertia than a 20", but it's not a "general principle" or a "law" and it depend on the wheel's construction.
In fact, you could make a 20" wheel that as the very same inertia and mass than a 29" one, so they would react the same, and if you have the same wheelbase, it would have the same stabilty, but certainy not the same manoeuvrability and general comportment.
So make your choices with that, and the more important : have fun on your bike, whatever the size you ride.
  • 3 0
 Just to throw in some confusion there is a little detail to add: the different angular speeds for the same linear speed when comparing different wheel sizes.

For the same increase in linear speed (displacement speed) between 2 bikes with differing wheel sizes the angular speed increase will be different, making the difference between accelerating a bigger wheel not as big as it may seem without including this detail.

That said I still prefer 26 inch wheels as they are stronger, cheaper and demand less skill to maneuver in tight places which is perfect for unskilled fat asses like myself. Also 26 inch quality tires are easier to find and cheaper to buy than they ever were.
  • 3 0
 So what I'm getting here is that more than 50% of people saw the same size wheel in the experiment above and thought to themselves what does this have to do with 26 vs. 29 inch wheels? Honestly, if you missed the weights and their spacing from the center and didn't make the connection even slightly......why even comment?
  • 1 0
 I know wtf right.
The classic scientific hypothesis.
"with all things being equal"
  • 3 0
 Im sorry but exactly which age old question is being answered here? What are we meant to be learning from this? There is nothing more than common sense and basic physics being demonstrated. Whilst I am not amazed that Mr Cunningham is capable of writing such nonsensical rubbish, I really find it hard to understand how he has used a simple (albeit completely elementary and unnecessary) experiment about hub weight to further fuel the debate on wheel sizes. I would've thought that he was beyond this kind of sensationalism but anything to get more traffic through the site eh.....

Perhaps he has actually learnt something from this which I find even more worrying.
  • 8 2
 Cool demonstration. Now lead hubs will be the next thing.
  • 4 0
 Why is this so novel? Have you seen a gymnast do a front or back flip layed out and do it fast? No they are always tucked because the rotation is faster.
  • 3 0
 I always thought they were tucked to hide the bulge.
  • 3 0
 I prefer thinking of ice skaters doing the arms out/arms in thingy as they spin and how their speed varies with the distribution of mass. It is the same weight and approximately the same energy and yet the speed varies immensely.
  • 1 0
 Pretty sure the ice skaters are putting their hands down to hide the bulge.
  • 8 2
 And remember, pick a wheel size.. then be a dick about it
  • 5 0
 I foresee the price of used 26'ers going back up... Call me a guru if you will.
  • 2 0
 At least where I live some riders are trying to dump their 29'ers to get on the 27.5 / 650b train and finding out if they do it it will be at a huge loss. I think most of them don't want to show weakness by going back to the old size they had been riding until 2 years ago.
I give it 2 or 3 years until it is generally accepted that there are no miracle wheels and that many of us haven't enough fitness or skills (or in my case both) to handle efficiently the bigger wheels and that some of the better riders we know really are faster on 29 inch wheels while others have no gain or loss from the choice.
  • 6 0
 I kick myself every-time I fall into the trap of reading an RC article...
  • 1 0
 RC knows how to stir up some drama. Do you not like drama?
  • 2 0
 "the results of e-thirteen's demonstration suggests that proponents of 26-inch wheels should not be discounted as the sport's angry villagers, reticent to accept any sort of change"

I don't recall anyone regarding 26" fans as 'angry villagers'; I do recall those constantly banging on about the amazingness of 29" wheels as being really annoying and being a mouthpiece for an industry desperately trying to screw its fans out of more cash; a walking talking sales brochure, if you like.
  • 2 0
 Some physics nerd has probably already said this, but because a 29er rolls a greater distance per revolution, this demo isn't relevant. The only difference in rolling wheels (and these aren't rolling wheels, they are both spinning on the same size spindle) is the mass, not the size of the wheel.
  • 2 0
 The ONLY thing this experiment describes is:
1) if given the SAME diameter round objects (both objects in video are the same diameter, the only difference is weight distribution),
2) and if ignoring opposing forces from the "trail" (the only opposing force demonstrated here is at or near the axis of objects, not friction at the radius due to the trail which is what most of us call rolling resistance, and air I guess, negligible)
3) and constant acceleration due to gravity (the linear and static track, not dynamic like trails, with bumps and more so infinitely long)...

Drum roll please: More weight toward the center of a object will accelerate that object more quickly laterally than if the if that same weight is positioned to the outside of an object of similar size and overall weight. Assuming the above^^^which this experiment represents. So to relate to bikes...if two 26" wheels that weight the same are rolling down a flat hill, the one with a higher mass density near the axis (light rim/ heavy hub) will ACCELERATE more quickly than the one with higher mass density near the rim (heavy rim/light hub).

A longer track with bumps and variable elevation would show that the outside weighted object would have a higher lateral speed and not decelerate at bumps and hills as quickly as the other.
  • 5 1
 We knew this. 26" wheels accelerate faster but bigger wheels with roll for a longer period of time.
  • 2 1
 Assuming they are on flat ground
  • 1 0
 Good call. I forgot that variable.
  • 1 0
 get big wheels rolling and they are difficult to stop. need more powerful brakes. but they are heavier too (normally). what does emily batty use?
  • 1 0
 Sometimes true. All of my 26" wheels are heavier than my 29 and 650 wheels though. Then again I'm using outlaws and double tracks for my DH wheels.
  • 1 0
 Weight does have to do with how well the bike handle all around but what wheel manufactures should be advertising for quicker acceleration is the moment of inertia. Any freshman college kid taking intro to physics should be able to tell you all about it. It's not that complicated but its something to consider when selecting a wheel.
  • 2 1
 Heavy wheels/tires are slower to accelerate AND slower to decelerate. The next trend will be 29 or 27.5 in the front, 26 in the back. Marketing will call it "THE MULLET" because of it's ability to roll over anything in it's path, and still have playful turning characteristics, and it will instantly change the head tube angle negating the need for an angleset. Unlimited options just by changing your wheel size...

All this just to explain why their hubs are heavy and it won't matter. That's one way to spin it.
  • 1 0
 he next trend will be 29 or 27.5 in the front, 26 in the back"
Been doing that for about 8 months. 650b front 26 rear aka B6er..
Great rollover on rooty stuff still fast rear wheel acceleration. It works very nicely and it very noticeable If out my 26 front back on adjust my geo so it is the same more or less in both situations via offset shock bushings
  • 5 2
 26-24-20 BOMB PROOF / 27.5 BIG CRACKER PROOF / 29 TALL FLEXY HEAVY LOUD CLAP PROOF - if you yell loud and hard at, it might crack.
  • 3 5
 At 240lbs I ride a 29er on jump trails at the DH park and never broken so much as a spoke. If you're breaking wheels you either have shit wheels or you're a sloppy ass rider.
  • 1 2
 You just made my day and made me laugh and whole bunch of people. LOL .

WOW DH? Do you ride it in DJ parks all day too?

Be brave and share with the world your secret prototype DH 29-er.

And on the relative subject of acceleration as noted in the topic of the article, coming from BMX background and racing people everywhere on all kind of bikes, nothing comes even close to instant and fast acceleration and speed gain of BMX with good tires and proper gearing ratios - that's why its so much fun. Smaller the wheel and bike - more room and fun on the trail, acceleration in technical climbs, manoeuvrability and control on skinny's, thin sections.
I have not broken rims doing drops or stair cases, maybe its the skill + the right bike and wheels for the terrain = a happy safe rider progressing. Nothing holing you back.

Cheers and don't be hating on 20-24-26er. Have fun on the trail!
  • 2 1
 Personaly I ride b6erSmile I sometimes miss my 26er front , it Was def more "playful"

But one my of riding buddies is 6'4 and and rides a 29er norco shin obi. he rides black diamond shore trails , whistler bike park , silverstar etc. Has to yet to break a wheel. Just blows up his rear shock routinely(fusion)
I can usually out sprint him on techy uphills he destroys me on anything downhill and smoother...
  • 2 1
 REDSTA you stupid no reading comprehension having dipshit. Not even going to explain it to you if you are that stupid.
  • 1 0
 Alias530 - You should be ashamed of your self for posting comments like that.

You probably know better than the guys who designed your 29er. The review of your 29er was probably done by a "stupid" professional, right, because obviously he doesn't know what your "secret" 29'er bike is actually capable of. Because you ride your 29'er like a god right? And you probably got all the medals stashed up somewhere, all dusty in a closet?

But why prove or explain anything, sure your secret 29er and rims are magic, plus your skills, you must be a famous sports athlete, no, maybe?

LOL>
  • 3 2
 besides all this bullshit
did anyone notice e-13's theory that its ok to make shitty stupid heavy hubs, because you can offset the weight by using lighter spokes and rims?
yeahhhhhhh
thats all i want in life. shittier lighter rims and spokes so i can wreck the important part of my wheel faster and hopefully buy more replacement parts to keep my bike running, all while having shitty feeling flexy wheels.
why doesn't anyone else make huge hubs?
because they're stupid.
quit being stupid
  • 3 0
 Forget it all and go ride your bike... 26, 27.5, 29 whatever. The only place it makes a significant difference is the bike companies bank account.
  • 2 0
 Need to throw some tight corners, switchbacks an Sbends into that test, none of us ride on perfectly smooth straight trails An we all know a smaller lighter wheel will handle better
  • 1 0
 Except when it doesn't. Why don't we ride on 16" or 20" wheels?
  • 1 0
 Except that now you're just going to to extremes to make a bullshit point
See many mtb dirt jumpers or 4Xers on 650b or 29?
  • 1 0
 You said smaller is better. Clearly that's not always the case.
  • 1 0
 YAAWWWWWWN
  • 1 0
 What an informative, fact-filled reply. The fact remains that in the real world, distance of the rotating mass from the center of the wheel as demonstrated here is not the only determinant of a wheel's efficiency or handling and you've done nothing to prove otherwise. Smaller is not always better.
  • 1 0
 Well I'm guessing you understand gyroscopic effect??
So let's take a 26 27.5 an 29er wheel with the same rim an tyre
We both know which wheel is gonna be lighter an due to gyroscopics more agile

Different wheel sizes have different advantages an disadvantages and in all honesty it's a tired debate

None of which relates to the above test
So yeah
Yawn
  • 1 0
 So you still haven't answered why we don't ride 16 inch wheels. If smaller is necessarily better, we should be, but clearly there are more variables at play than the physics of a spinning wheel. And you're right--none of those advantages relate to the above test because the test itself is irrelevant to the real world.
  • 1 0
 Since when has 16inch been an mtb wheel size?
If you'd have said 24 you'd have a valid point instead of taking my words out of context just to make a bullshit point
  • 1 0
 There isn't a 16-inch wheel size for MTB because it wouldn't work for real world riding. By your "gyroscopic effect" rationale and the silly E-Thirteen demo, we should all want them because it would be so awesome, but in the real world they would suck massively. SMALLER IS NOT ALWAYS BETTER.
  • 1 0
 I didn't say smaller is better I said smaller will handle better......
  • 2 0
 Holy cow guys. This is such simple physics. The object will rotate faster when the mass is concentrated toward the center of mass. Im pretty sure anybody who's taken physics in high school knows this.
  • 1 0
 If I can accelerate faster the better. I don't ride on a flat straight road. Rolling over rocks and logs, turns and berms will cause me to slow down, let's accelerate! I don't dream about cars and bikes b/c in the long run they will go faster, it's because they launch out of the gates like rockets.
  • 2 0
 Plus, I'm not gonna new everything. Good bye Giant Glory! Hello anything else 26"
  • 1 0
 Watch SID the science kid they explain better and they do research thoroughly. I think this experiment is just, ummmm! I have 26 and 27.5 and I am telling you now 27.5 is faster in rolling depending on tyres width (Thinner 2.0- 2.2 fast... 2.35- 2.50 slower) If that make sense. Smile Only in my Science kid observation!
  • 2 1
 Anyone who needs proof about how much faster small wheel accelerate should try doing gates with BMX riders. Try them on your 26", 27.5" or 29" wheels, then borrow a 20". The difference in acceleration is unreal. Add to that how much more pump you get with 20" wheels, I'm sticking to 20", 24" and 26" wheels.
  • 1 0
 @Bulletproof and many other techbabble tinkerers; you are not more correct in your understanding because you know a few formulas.

You are all neglecting that it is not only the bike that is accelerating, it's the bike and the rider. The difference in thecontribution of rotary inertia to the total moment of inertia of rider and bike is negligible, and the energy required to increase the inertia moment is the same.

As such handling characteristics is a much more important factor.
  • 4 0
 my 26' fits just perfect in my car. other wheel sizes are not an option anyway Big Grin
  • 5 0
 * cough cough * 26 AINT DEAD!!!
  • 1 0
 one thing everyone seems to forget, we already know a 29" accelerates like a dog compared to the 26", this test is also showing only weight placement, nothing to do with diameter and a test like this shows nothing about what is happening on a trail. one last comment that nobody seems to be mentioning, the wheel in front almost stops dead at the end while the other kept spinning after impact, that could be anything from the material differences between what stopped the first wheel vs wheel to wheel impact or even surface area differing although they look pretty similar. This is just an observation as all my bikes happen to be 26" my next will be tween or 29 whether I want it or not, but all bikes should be fun, if your bike isn't, it probably has more than wheel size against it.
  • 1 0
 thank you to people mentioning energy spent. A parameter that most of you seem to forget defending inertia and whatever.. before reaching enough inertia, you need to reach high speed, and with higher diameter this goal requires much more energy and time than with a lower diameter set of wheels.So if you're only runnig downhill and not technical tracks, for sur 29" is made for you, but i don't think XC is made of 100% downhill on clear grounds... What about downhill race? For sur it always goes down. Is it generaly on clear grounds.. hum I don't think so...
  • 1 0
 Outer rotational mass. This demonstrates what happens from a rolling start down a hill. All the same the greater the outer rotational mass the more energy needed to accelerate. On that note a heavy bike with light weight wheels will work better than a uber light bike with heavy tires.
  • 1 0
 horsepower and torque overcomes everything. the real question is how much stronger does a fat ass have to be over a skinny ass to compensate for the lbs or kgs? focus on your damn cardio and strength and quit fantasizing about it being your bike making you slow or getting your ass kicked up that hill.. .
  • 1 0
 simple! further from the axis=larger moment of inertia, angular acceleration is inversely proportional to inertia (provided with the same crank torque) the larger inertia (27.5 or 29 inch) the smaller the angular acceleration Smile and I'm just a student wooooop
  • 1 0
 I didn't scroll through all 348 comments, so this may be redundant: While this demo does apply to distributing the mass differently, it DOES NOT APPLY TO WHEEL SIZE. Yes, moment of inertia is greater for bigger wheels due to 1) the radius being bigger and 2) given the same spokes, rim extrusion, etc, the bigger wheel will be heavier. BUT angular velocity is also less for the same linear velocity. I can do the math, but PB isn't a whiteboard, nor does anyone care.

The point is, angular momentum is actually quite similar and is only bigger for larger wheels because they tend to be heavier.

This demo is not valid because the "axle" (what the wheels in the demo are rolling on) is the same size for both wheels. You would need to have a larger axle in order to represent different wheel sizes if you wanted to use a similar demo.
  • 1 0
 We could watch figure skaters demonstrate this same concept when they bring their bodies in at tight as possible to spin faster. Or perform a very scientific butts-in/butts-out experiment on a merry go round for a similar effect.
  • 1 0
 Does anyone remember when hydraulic brakes were too heavy, expensive and dangerous? Full suspension bikes were too heavy and not a "real" mountain bike? Downhill was not really mountain biking and Freeriding (All Mountain) was just an excuse to ride illegal trails? The sport evolves and one bike, or for this matter, one wheel size does not fit every style, personal preference or strength and type of riding. Should we all be riding rigid, steel, 26 inch, tubed, toe clipped, cantilever braked bike? How does the bicycle industry's conspiracy against the consumer exist if nobody's holding a gun to your head to ride.
  • 1 0
 "E-Thirteen answers question about mountain bike wheel size with high school physics demonstration that has nothing to do with mountain bikes, wheels or size!"

Boy howdy! Doing laboratory tests using actual wheels would be massively unreliable. Using weights suspended by metal rods spinning down metal poles is downright irrelevant. The only even remotely logical take away is that the disk with the more centralized mass accelerates faster when equal force (gravity) is applied to both. Which is something, you know, everyone already knew. 26ers accelerate faster; we get it.

Slow clap E-Thirteen. Way to incite the already insufferably idiotic wheel-size war with something that's somehow even dumber.
  • 1 0
 Also, the placement of the silver weights make zero sense. It's not like 26ers have their rims and tires hugging the hub. Dumb dumb dumb dumb dumb.
  • 1 0
 The human mind is still in its infantile evolutionary stage.

Give us a solid few thousand years, and I think well settle on a wheel size that isn't defined by an integer from an imaginary length scale.

I mean, how f*cked would we all be if the inch was a 3/26" longer, right!? Then a 26" would be 29"!

Forget about 26", 650b, and 29". The optimal wheel size likely won't be discovered for thousands of years...and by then we'll all be riding hovering e-bikes anyways so it really won't matter.
  • 1 0
 That video really doesn't prove anything, since the "slow" wheel has more rotational inertia and needs to roll over things, which the larger wheel will do better. If rotational inertia were the only factor in how a wheel rides, then we should all be on rollerblade wheels because those are really small.
  • 1 0
 @RichardCunningham: If you want to write scientific, you should stay scientific. There is no surprise in what we see in this video, and it is correct for what e13 wants to demonstrate, but not to compare wheel sizes. Besides being overexaggerated (it needs to be, otherwise we would not see anything), it is also not correct because both "wheels" roll on the same diameter. So what we see is the difference in angular accelaration, but a larger wheel needs less angular acceleration than a smaller one to get the same tangential acceleration.
Still, if you do the math, a smaller wheel will accelerate faster (if you consider just the tire, it is linear to the diameter). But then there are a lot of factors not taken into account, otherwise XC racers would ride 16" wheels and accelerate rocket-like.
Most scientific tests I came across that did real world testing suggest that 29" is faster for XC use. But then we see that you can win on 650b or 29", so most probably the whole discussion just comes down to personal preferences.
  • 1 0
 The two wheels have different aerodynamics. If the metal inserts in the first wheel are positioned roughly at half the radius of those in the second wheel, then their velocity (for the same axle velocity) is half of those in the second wheel. Thus their resistance to the "wind" is much lower (wind resistance is proportional to velocity^2). Thus, strictly on aerodynamics the first wheel should travel faster as shown in the video. A more appropriate/fair test would be where the thickness of the plastic part of the wheels is the same as that of the metal inserts.
  • 1 0
 Ha - this is all rubbish!

When I change from my 26" MTB bike to my 700c X-cross I notice it is much slower on all surfaces, and when I change from my 700c back to my 26"MTB. Guess what? Yep - I notice it is also slower on all surfaces.

Only the fountain of youth will solve this worsening problem...
  • 1 0
 I recognized the bigger wheel marketing BS for what it was when it started. I don't even read past "27.5" on new frame reviews. Sorry, just not interested in being separated from my money for snake oil. I'll buy used carbon 26" frames before I'll spend $2K plus for a frame that is designed around slower, more easily damaged wheels with fewer tire & fork choices. That said, it is easier to fool people than to convince them they have been fooled.
  • 5 1
 Im gonna put heavy spoke a dokes near my hubs....see ya bitches
  • 2 1
 oooh, I just thought of something. Does this mean that I need smaller disc rotors on a 29er? Not as much inertia. Weight savings...but wait...it's at the center...so now the wheel is even slower???
  • 1 0
 If you try adding 2 kg to the hub you will feel the effect of changing to a slightly heavier tire, some people claiming (I think for dramatic effect) it is like adding 60 gram in tire weight. Disc rotor weight is of absolutely no effect to the speed and acceleration of the wheel, yet can be of catastrophic effect when it comes to stopping or crashing into the trees.
  • 1 0
 But the weight of an 8" rotor is further away from the center of mass...and there is more of it. Will my tires ever roll? Mother of PEARL!!! (in my Old Spice voice)
  • 5 2
 I TOLD YOU MANY TIMES, RIDE A 26 = SMART. But you can find a lot of "PINKBIKEMONKEYS" with money and no brains for sure.
  • 1 0
 What ever this article was intended for aside, I loved all my 26 full suspensions, loved my last two 29 full suspensions, but my new Surly Krampus whose wheels measure out to 31.5 has a ride like no other!!!
  • 3 3
 Experiment has a major flaw.

1. The wheels should be same weight but different outer diameter.
2. For each revolution the 29er wheel will cover 738.84mm (2.3 inch tyre) vs 675.84mm of a 26inch wheel.

So even though the 26inch wheel will spin faster at the hub (Where this experiment is measuring) it won't cover the same distance. Really each full revolution needs to be added to get distance covered.

This will translate to distance covered on the ground and will give you that acceleration number.

Or maybe I am just talking out of my ass.
  • 4 1
 I like big butts...and I cannot lie. But wheels I don't really care about that much.
  • 3 0
 ughh. highschool physics should be a requirement to comment on this article
  • 1 0
 I think we all answered this "age old question" when we were young and would sit in arm chairs... When your spinning, you put your legs out and you go slower. You tuck them in and you go faster! Cyntrifical force!
  • 1 1
 i thought the big wheel concept was about rolling over bumps... i mean i am on 26 i wouldnt change for 27.5 or 29... but bigger wheel size whill roll over bumps better than the 26... so............. it will loose less speed over bumps... its not about the spin on the wheel on its own wheight over an axle... and also bigger wheels will bent easier on whips and things like that thats why i wont change from 26 to bigger... its the best to send it without bending it and to change wheel size i would have to change fork frame rims spokes tires tubes ... thats too much money for so litle diference...
  • 1 0
 A question.
2 bikes, identical in every way.
2 people One weighs 80kgs.The other weighs 100kgs.
Both going 20 mph on a flat road.
They both stop pedalling at the exact same time.

Who rolls longer/further ?
  • 1 0
 is the fat person the same size as the not-so-fat one and have the same aerodynamic drag?
actually its the person with the shaved legs
  • 1 1
 Am I missing something here. I am not trying to be obtuse (Yes, this word far exceeds my normal vocabulary). But the whole point of this experiment was to show that the fact that E13 hubs weigh more, hence resulting in a heavier wheel than other brands/builds doesn't adversely affect how the wheel excellerates or rolls. How everyone started arguing about wheel size is beyond me. I have always been curious about trying a E13 Chub Hub, laced with sapim CX ray spokes, to a LB carbon Rim for either my 29er or 650B. But have been thrown off by the overall weight of the hub. I just haven't been able to unwrap my head around that fact. But this experiment shows me that I need to let go of the numbers and perhaps trust that it won't feel heavier or slower to me.
  • 1 0
 Note the one with the smaller diameter weights only spun a half a revolution when it hit the end, while the one with the larger diameter weights completed about 3 revolutions when it hit the end. That has to mean something.
  • 4 1
 Ok guys get your gloves on here we go!!!
  • 7 3
 BECAUSE SCIENCE!
  • 4 1
 I suppose many negative comments will be rolling in soon....
  • 3 0
 I just have 'faith' my wheels will roll faster
  • 5 1
 Yeah! Science bitches!!!
  • 2 0
 this just proves that i ride faster then everyone because i run 24's. hahahahaha.
  • 1 2
 Because the tire is wheel's heaviest component, by nature, a 29er wheel should be the worst offender of the three diameters, yet the 29er's popularity among XC racers.

why? because most xc bikes lack enough trail to handle correctly. why? because xc riders associate heavy steering with lack of efficiency IMO
  • 3 1
 Pay attention to the second wheel when it hits the first wheel at the end, it keeps on rolling. hmmmm....
  • 1 2
 to every guy defending "higher diameter=higher speed": may I remind you of the fact that the low nombers of teeth on a 29 rings and the high number of teeth on a race BMX is not a coincidence.
In other words: you can compensate a lower wheel size by a higher teeth number.
having said that, how many of you are capable to reach 60mph because it has a 60t ring on his 26 bike? technicaly, as higher wheel size increase the distance run per round, more teeth implies more wheel rounds per pedaling round. (please excuse my english)
But still we can't reach that speed because some of you seem to forget one parameter: the energy you have to put on your pedals.
And suprisingly, the discipline more needy in energy/calories/power is the one which more uses 29" .
more climbing and flat than pure down hill so we can't say that launch those wheels is as easy as on a downhill race.

So now I'm pretty sure that the calories burned are much higher running a set of 29" than the calories burned on a set of 26" (trying to reach the top speed of the smallest set).
To compare it to the teeth number issue, it is obvious that we can't reach 60mph even having an hypotetic 60t ring on a flat road for example, but even at a lower speed it would be more exhausting to maintain a 20mph speed with a 60t ring than with a "normal" 36 or 38t ring... just because you need much more calories, power to turn such a big ring to that speed, the accelaration is less eficient and the top speed is more difficult to maintain on long terme.

Hopefully my english is clear enough to make myself understood..
  • 2 0
 60 tooth front ring?Id like to see that.
I have an old gt karakoram that is convert to road use. 1 inch tires and a whopping spesh 54 tooth front ring. In my early 20's I could hit 60km on level road but only maintain 50km
  • 1 0
 60t to exagerate things and make it clear that at some point you can technicaly and physicaly improve the top speed capability of the bike, if legs don't have fuel dragging this, it's just all pointless.. otherwise they would just put higher wheel diameter and teeth number on track bikes to reach even higher top speed ^^
  • 2 1
 We have enough gearing options nowadays that gearing, and the circumference of a wheel do not have an impact on its top speed. A 29" tire carries more inertia, therefore it can keep going fast
  • 1 0
 But still, before reaching the same speed as you could do easier with lower sized wheel, you need more time and calories to let inertia do the rest, and not to mention climbing sections, SO in the end if you burn all your energy on acceleration, you have not much left to add to inertia help, cause inertia doesn't do the whole job, but legs do.
And I would add, yes the circumference of a wheel does has effect on top speed (on same gearing and same pedaling cadence but with 2 different diameter, you definitly cover dirent distances on one pedale round, in other word on the same cadence or time you need to turn your crank you cover more distance so you go faster... end of the story
  • 1 0
 Correct. If people could just think of wheels like sprockets or gears, this discussion would already be over.
  • 4 1
 who cares. ride bikes, drink beer.
  • 1 0
 Good call
  • 1 0
 I like my wagon wheeled Spesh Enduro. But I still have the small tire, long travel, Canfield to bomb down hills with. To each his own I say.
  • 1 0
 Yeah why can't they just do the exact same test (albeit longer track configuration) with the actual tires 26 vs. 29 with the same hub, spokes, rim, tube and tire set up?
  • 3 0
 Just gonna drink this beer and eat this pizza.
  • 2 0
 29ers are super cool. Just kidding they are super gay!! I'm fast way faster than you!!!
  • 1 2
 WRONG.
Bikes roll on the ground, not on the axle. If the experiment is done correctly (put the wheels on the table and tilt it, or research rolling wheels), you will see that:

For Power required to Accelerate a rolling bike - effect of Rotating weight is the same as Non-Rotating weight. (There is actually like a 0.5% difference).
Therefore, bikes of equal weight with different wheel size require the same power to accelerate.

Regarding turning, traction, rolling over stuff, etc. I have no idea.
  • 1 0
 And bikes with equal total weight, one with light wheels / heavy frame, the other heavy wheels / light frame … also require the same power to accelerate.
  • 1 0
 Perhaps e-thirteen should spend some more time on customer service and making sure their wheel bearings can last more than a month instead of this crap!
  • 2 0
 oh cmon, everybody, shut definitely down your internet connection and go out for a ride now... :-)
  • 1 0
 How about considering peddaling effort and calf size in that experiment? Will I, an avarage Joe, or weekend warrior be faster on 29er than Remy Absalon on 26er or even 20er?
  • 2 0
 16/20/24/26/27.5/29/32

The balance between fast and slow always lay in the middle.
  • 1 1
 these are so far from real world results steel spindles on steel rails perfectly smooth , whatever, Pinkbike why do you post such ridiculous articles? "watch and learn" more like watch and waste my time lol
  • 1 0
 "... The sport's angry villagers, reticent to accept any sort of change."

Reticent: I do not think this word means what you think it means.
  • 2 0
 Just ride your effn bike.. 20, 26, 27.5, 29... whatever it is and get out there and shred!
  • 1 0
 Again.... Why does anybody even care about this anymore? All three wheel sizes have their places.Try the different wheels, ride what you like.
  • 1 1
 Question.

2 People On Identical bikes.
1 Person Weighing 80Kgs And the Other weighing 100Kgs.

Both cycling at 20Mph on a dead straight road.
Both Stop pedaling At Exact same time...

Who Rolls Longer/Further ??
  • 2 0
 Practitioners always want the 26 ". Why manufacturers are bored stiff to do us ??? 27.5 and 29 (29 is the end of life!)
  • 1 0
 ...I used to own a blue MKI Ford Fiesta, god it was shit !! ...I spent about 6 months doing it up then totalled it on the second drive...
  • 1 0
 I've got layman's terms here. . All this shows is that a smaller rotational angle under no friction is capable of spinning faster.
  • 3 1
 Marketing in action! Cool demonstration(no BS, I like it)
  • 3 1
 O man laws of physics nooo
  • 3 2
 yeah, buy lighter rims and broke it faster then buy another! Sorry, I rather go slower, but on tuff parts
  • 4 2
 so obviously 36er is the way go
  • 3 1
 Every 26 guy just added this to his favorites.
  • 3 2
 Why is everyone on about wheel size?! This demo is for the weight argument with regards to tyres and rims........
  • 6 1
 erm... because wheel size affects the distance from the hub of the wieght of your tyres and rims perhaps?
  • 1 0
 Well here's the quote from the very beginning of the article:

"Almost every cyclists insists that, if two wheels weigh the same, the one with the lighter rim and tire will accelerate faster - but where is the proof? Every wheel review worth reading either states or implies that there is a noticeable difference when accelerating a lighter or heavier wheel, but just how significant that effect may be, or whether it is largely a figment of the test rider's imagination has been cause for an endless round of debate. Add the wheel-diameter war to the equation and the discussion becomes less scientific and more emotional. Until now, however, the argument has been an intellectual one."

So- I say again, the main point of this article is the conversations that always go on about rotational weight.
  • 2 0
 24 rear and 26 front... Best of two worlds.
  • 4 2
 29" wheels were invented to sell more bikes end of story.....
  • 4 0
 As a pigheaded user of 26 inch wheels I have to say neither wheel is all they say it is.
There is no miracle wheel.
What was done to sell more bike was all the hype and the "we will not make anymore top of the range 26 inch bikes" some manufacturers did. Now that is stupid marketing.

There are no miracles and if there is a "goldylocks wheel" it will always depend on the rider, his skill and fitness level and what he is doing with it.
  • 2 0
 Funny how seeing is believing
  • 3 1
 SHUUUUUUUUTTTTT UPPPP WIIIIIITHHHH THIIIIIS ALLLLLLLREADDDDDYYYYY
  • 1 0
 horrible....
  • 1 0
 so make lighter hoops and heavier hubs... obviously this demonstration extremely over exaggerates the differences.
  • 1 1
 Notice how the one with weights closer to hub stop once it hit the bump and the one with weights on the outside hit the bump and sped up!!! I'm buying a 27er!!!
  • 1 1
 Does this means that this is the cause why china has huge population? Because they have smaller willy's that moves faster....
I mean wheels!!!!
  • 1 0
 In addition to being pointless trolling, extrapolating this to wheel size is just incorrect.
  • 1 0
 Couldn't they just lace up wheels to a hub this shape and do the same test with real world products?
  • 2 0
 This just proves there is nothing on the internet I can't fap to.
  • 1 0
 it would be interesting if the rails had bumps - which wheel should keep his inertia Smile
  • 1 0
 those are definitely mountain bike wheels riding in the woods over roots and rocks. so it seems we now have the final word.
  • 1 0
 lol this experiment makes e13 look so damn stupid they have embaressed themselves extremely here.
  • 1 0
 Or, we could all just go out and ride our bikes and quite bitching about wheel sizes, and go with what we like
  • 1 0
 drop them both off the tower of Pisa and they will accelerate at the same rate
  • 1 0
 The proliferation of 27.5 frames makes it very easy to not spend money on a new one.
  • 2 1
 Uhhhhh.......oh...oh..........this could get downright nuts.
  • 6 0
 Which kind? The kind like peanuts where the mass is in the middle or brazil nuts where the mass is evenly distributed. Your point is moot!!!
  • 2 1
 I blame science for this impeding battle
  • 1 0
 Impeding...I'm peeding...I am peeding....I am peeing...I am peedi again....I AM PEATY...Again!!!
  • 2 0
 Can'o'worms.
  • 1 0
 Can'o'worms = click-bait.
Personally I like it.
  • 4 3
 OMG people... this has nothing to do with size...
  • 2 2
 Exactly my point!
  • 5 0
 yeah , exactly, this just shows that he more weight you add to the outer part of a wheel ( lets call that a rim for all intend of purposes ) the more energy it requires to move it at equal speed than a wheel with smaller "rim" . . . absolutely nothing to do with with size but more with weight distribution...oh wait, does a 29" wheel rim weight more than a 26" ? :-)
  • 1 2
 This makes no sense as to wheel size. This proves that of the two wheels of the same diameter, the one with more mass closer to the axle will accelerate faster that the one with more mass further from the axle. Yes, on a bike, the actual rim will weigh more, but the entire center of the wheel up until the diameter of the smaller wheel will weigh exactly the same. That isn't the case here, meaning that this doesn't prove anything.
  • 3 1
 Just go and ride!!!!
  • 2 0
 PEDAL HARDER!!!!!
  • 2 1
 Thats all good until you put rocks and ruts in front of that wheel.
  • 5 0
 And then eventually you taco the front wheel on the 29'r.
  • 2 0
 but i like tacos....
  • 1 0
 NOOOOOOOOOOOOOOOOOOOOOOOOOOO.........Smile
  • 1 1
 Can Pinkbike please introduce props on articles? So I can neg prop this one into oblivion?
  • 1 0
 Yes i get it! So tyre on inside spokes on outside?

To the shed!
  • 1 0
 Make a "waved" down sloped rail (to demonstrate bumps) and let's retest...
  • 1 0
 Phew! I thought I was going to get Rick Astleyed for a second.
  • 1 0
 If you write an article mentioning wheels, you're gonna have a bad time...
  • 1 0
 I want one for my desk at work to go with my swinging ball thing .
  • 2 1
 Can't we just all ride bikes without fighting over wheel size?
  • 2 1
 Banana bread is the better option
  • 1 1
 650b will produce a new generation of superhuman cyclists. can 26" claim that? ha, didn't think so! game over
  • 1 0
 My hovercraft is full of eels ...
  • 2 0
 my lobsters are in a tank, but neither knows how to drive it!
  • 2 0
 Yeeeh! 26'' ftw!
  • 1 0
 424 comments and counting. Nice
  • 1 0
 It's easier to fool people than to convince them they have been fooled.
  • 1 0
 I'll keep my 26"!!!!! The f*ck 650b or 29" is a marketing action!
  • 2 2
 Brace yourselves... Incoming wheel debate comments...
  • 4 2
 u wot m8?
  • 4 5
 This only shows weight, not diameter. If a 26 and 29 rotate at the same rpms the 29 covers more ground.
  • 6 2
 you do realize a 29" RIM weight MORE than a 26" right?To get your 29" rim to rotate at the same RPMS it will require MORE energy...from your legs. :-)
  • 2 0
 titanium bolts or some foam grips should be enough to compensate
  • 1 1
 yes, tuumbaq, but at the same rpms the 29 is traveling faster.... bigger diameter.... one rotation of a 26 covers 81.6 inches of ground, while a 29er covers 91.1inches per roatation about 11.6% farther per rotation.... SO, the question still remains...
  • 1 1
 I like monkeys and spaceships! Purple! Yaaay!!!!!
  • 1 0
 Told u so?
  • 1 0
 Because Math. The End.
  • 1 0
 24"s forever!!!!
  • 1 4
 Looks more like a simple way to display the difference between rotation of a small cog and a large cog in a cassette if you ask me... :-/
  • 1 2
 YOU ARE FIRED!!! 'neff said
  • 2 3
 Shots Fired...
  • 1 2
 Nope......BOMB dropped!
  • 1 2
 A2+B2=C2
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