Video: Does Your Suspension Really Work Better Without a Chain?

Apr 15, 2020 at 18:08
by Mike Kazimer  

Aaron Gwin's winning chainless run at Leogang in 2015 is firmly cemented in the history books, and it's often cited as an example of how much better a bike's suspension can work without a chain. Is that actually the case? And what about pedal kickback, another phenomenon that some riders say they can immediately notice, while it's not an issue at all for others?

Steve Mathews from Vorsprung Suspension dives deeper into these topics with several excellent examples that make it easy to visualize exactly what's happening out on the trail.

If you'd like to learn more about anti-squat, Pinkbike's Dan Roberts recently put together an in-depth primer on the subject - you can read that here.


167 Comments

  • 121 9
 Too much math, engineering and physics...

Me like ride mountain bike.

Me glad engineer man/woman design bike to make it ride good.
  • 23 0
 Hahah, these videos are definitely not for everyone Smile
  • 1 0
 lol
  • 15 0
 @VorsprungSuspension: I loved it. Very interesting! Thanks for making them.
  • 2 0
 @VorsprungSuspension: just wondering: would you say the STFU chain "damper" has a chance to improve that? It should reduce chain bounce. On the upper side only but still.
  • 2 0
 I'm with you. Bikes cool. I ride bikes. Thanks engineering man or woman for making my bike.
  • 9 0
 Me ride single speed rigid bike. Me just pedal and no think.
  • 8 0
 @fartymarty: Single speeders get off more.
  • 1 0
 @EnduroManiac: I was thinking that too...in theory the design of the STFU damper "holds up" the chain above the stay and reduces it's lengthening then it should (again in theory) work to reduce the effect of the downward elongation of the chain and help the situation.
  • 3 0
 @VorsprungSuspension: that "f@ck this" comment was perfectly timed and delivered. You rule! I just about hit the back button immediately when I saw that board LOL.
  • 3 1
 @VorsprungSuspension: I think that the main problem is poor physics teachers. I mean, understanding a few vectors is not that hard, is it? But for whatever reason this is treated as a mystery or even some dark religion Smile
I still remember when I took a physics faculty and got a teacher who actually understood physics, as opposed to a "standard" teacher which could only draw formulas on a blackboard.
  • 1 0
 TLDR, "the wheel travels downwards when you pedal, giving you more traction, and pedaling efficiency, but may also cause a small amount of pedal feedback when you compress the suspension fast, at low speeds". It's basically a trade off, if you want less of this effect, buy a bike where the rear suspension/chainstay pivots closer to the bottom bracket.
  • 89 0
 The main benefit of having your chain break is the motivation to not brake so much.
  • 11 0
 Yep. I’ve experienced it myself. One of my fastest runs on a local DH trail was after my chain broke near the top of the trail. There’s no motivation quite like the thought of having to push your bike on a DH trail.
  • 4 0
 and it's weirdly quiet
  • 3 0
 and pumping everywhere possible!
  • 3 0
 The biggest gains are psychological for sure. Not braking, lack of noise, not even having the drag of the chain to provide resistance against spinning the cranks to a different position - all of those play a part I think.
  • 30 0
 He's so dreamy.
  • 281 0
 Username checks out
  • 1 0
 @sampolicky: Bravo. Bravo.
  • 5 0
 McDreamy is taken — henceforth he shall be known as McSpringy.
  • 3 1
 @WRCDH: underrated comment
  • 22 0
 Ok folks. It is clear that everyone is faster with a broken chain. Why would we need a special chainring thingie that cost hundreds of dollars - or a lesson in post graduate physics?

I have a box of worn out DA and XTR chains. I will sell for 100 bucks (will even throw in shipping - I am a nice guy) SO YOU TOO can be guaranteed that your chain will bust at the start of a run! Almost free speed. Also use the wrong chain tool to make a failure certain.
  • 18 0
 I have a question to the author: if the effect only really happens when the rear hub is engaged, does that mean a higher engagement rear hub would give worse suspension feel than a low engagement hub? I assume so.
* even at higher speeds the hub will still get engaged as there is a lesser degree of engagement. And so hubs that have instant engagement will have the most kick back
  • 8 0
 I thought the same thing. Then remembered I have hope hubs so probably why iv never noticed it.
  • 4 0
 Yes, it does indeed
  • 3 0
 Not Steve, but I can address it. You're partially correct. Steve was saying the hub may not even engage, but yes, faster hub engagement makes it more likely. The next question is whether anything meaningful happens if the hub does engage - i.e. are the kickback forces enough to matter. At worst, only a little. In the overall picture of all forces acting on the suspension and your body, these are rather small, if they even occur.
  • 5 0
 I'm inclined to say no, it doesn't matter. If the wheel is spinning faster than the cassette it doesn't matter. Consider coasting down a hill and you pedal slowly. It doesn't matter how quickly the hub engages if you aren't spinning the cassette faster than the wheel. Slow wheelie drops yes it does make a difference but that's not incredibly common unless you're Chris Akrigg
  • 2 0
 Yes. It also matters for which gear you are in as well. If you are in smaller cogs, the same chain growth length will correspond to a bigger radial change in wheel rotation that is necessary to eliminate pedal kickback.
  • 1 0
 @natemeyer: But you aren't taking into account the ultrafast movement of the suspension pivots and how those forces could cause some interference. It's not just coasting a bike downhill, it's coasting a constantly moving suspended mechanical contraption downhill.
  • 2 0
 @DoubleCrownAddict: Yes, it does take that into account. The shaft speed of the shock has a known upper range, which represents the fastest realistic movement of the suspension. This allows us to calculate the fastest realistic rate of chainstay elongation, which leads to the fastest realistic rate of kickback movement. We can calculate the speed required for the bike to be traveling to "spool out" chain faster than kickback is "taking up chain". This calculation shows that kickback is realistically possible to occur *at all* only on some bikes, only in some sprockets, only in extreme situations. Even if it does occur, it's even more unlikely for it to occur with enough force and movement to be *problematic* kickback.

The other factor, as Steve describes in his video, is chain bounce. This adds another variable, though the force of the tug at your feet and your suspension due to chain bounce is not large, compared to the forces moving your suspension and the force required to support your body during an impact.
  • 1 0
 @natemeyer: Chris Akrigg!
  • 15 0
 Alternative question: Does my chain works better without any suspension?

Hardtailer private joke; sorry.
  • 8 0
 Yes. In fact I recommend replacing your rear shock with a steel bar for optimum chain efficiency Smile
  • 33 19
 He lost me when he said the brakes were set up moto style "the proper way" lol
  • 24 6
 @sampolicky: the only way
  • 4 1
 I remember some years ago everyone in the Top 10 of WC DH was running moto, because it was Commonwealth countries and a few French who chose moto style.
  • 7 2
 Who cares, run whatcha brung.
  • 9 17
flag Aptlynamed (Apr 15, 2020 at 23:45) (Below Threshold)
 Well for mtb (or any type of riding) the front brake is the most important, so it makes sense that you use your strongest hand for that, which is the right hand for most people.
  • 23 0
 @Aptlynamed: Are you still riding cantilever brakes from the 80's?
  • 3 0
 @bigtim: I guess he doesn't necessarily mean stronger, maybe more controlled (if you're right handed, of course). I've no idea which brake I actually modulate more - all I know is it's too late for me to change anyway!
  • 2 2
 @bigtim: Your 'good' hand is not only stronger but also has better precision. Same with handwriting, guitar playing etc.
  • 13 0
 If you try going moto once in a while, it feels like someone is braking for you
  • 5 3
 @Aptlynamed: yeah exactly. I don’t get the moto reference because isn’t one of the brake levers a clutch on a motorbike? But yeah you want to be operating the front brake with your good hand and most of the world’s population is right handed. Same reason you should drive on the left. People who live in countries that drive on the right operate the important part, the steering wheel with their weak arm and change gear with their good arm which is obviously stupid.
  • 10 1
 It's not moto style, it's scooter style. Scooters have both handbrakes setup like that, motos do not.
  • 6 0
 I ride rear brake on the right, and therefore I can do waaaaaaaaaay better skids than all of you with lefty rear brakes! POWER FINGERS!!!
  • 1 0
 @Aptlynamed:

I agree that most tactile hand should ideally run front brake. Or is it that the tactile hand should run the brake thats easy to lock up? Hmm
  • 1 0
 @Aptlynamed: your good hand may be weaker hard to say
  • 1 0
 @Aptlynamed: that's why right handed guitarists fret with their left hand
  • 3 0
 @thenotoriousmic: It's moto style because the front brake is on the right bar on a motorcycle. I've never bothered swapping to a moto style setup, but it does seem odd that bikes ended up with controls set up backwards from their engine-powered brethren. It hasn't caused muscle memory issues on the street, but I suspect I'd have issues if I started riding dirt bikes.
  • 2 0
 @Mojo348: ahh yes, the stranger as they like to call it
  • 3 1
 @Aptlynamed: or my reasoning for keeping front brake on the left because I don't want one hand taking on front braking and shifting duties.
  • 1 0
 @lncorgnito: Moto style: feels like someone else
  • 2 0
 I thought it based on which side of the road you drove so you could signal when needing to cross the opposing carriageway and still control the back brake.
  • 1 0
 @bigtim: I dunno about you but my front canti hand is farking massive.
  • 8 0
 Somewhere in the world, R-M-R is cackling like a madman screaming "I TOLD YOU SO!!! I TOLD YOU SO!"

Steve is a f*ckin wizard. Reminds me of Jesse from Fast and the Furious.
  • 1 0
 funny that he was right and wrong at the same time, as in the real world or on rough terrain if you will the chain can not keep the freewheel disengaged, which leads to a highly incosistant feedback scenario.
  • 4 1
 @Brasher: Is there any other way to cackle?

@optimumnotmaximum: Was I wrong? Here's what I wrote to you a minute ago in the other thread:

1. Somewhere in this thread - or maybe it was in the forums, or maybe both - I already mentioned the inertial effects of the chain. This isn't the first time someone has thought of it. Steve wasn't the first, I wasn't the first - I'm sure someone thought of it a hundred years ago. Most aspects of bicycle physics have been known for a long time.

2. While I don't disagree with Steve - he's both tremendously clever *and* has outstanding critical thinking, so I doubt I'll ever strongly disagree with him - I wish he had done more to address the magnitude of kickback due to the chain bounce effect. It's really not much. His point is that it's an often overlooked variable and it's non-zero, but it's not huge. The force you feel in your feet due to supporting your body weight during an impact is so much larger that it's unlikely the possible addition of the chain bounce effect will even be felt, let alone cause enough of a detrimental effect to be worth worrying about.
  • 1 0
 @R-M-R: i agree that you are not proven wrong -just because a clever person says something different or adds an aspect. I also agree with your 2. point -partly. I wish Steve or anyone was able to quantify this effect. What i understood is, that the bouncing chain will make it impossible for the freehub to disengage at all times while coasting.

I also dont think you feel a big kickback, but i assume there is a negative effect on how freely your suspension is able to work.
  • 3 1
 @optimumnotmaximum:

1. You said I "was right and wrong at the same time". I wanted to address that remark by pointing out I *did* mention the inertial effects of the chain.

2. I'm not going to derive the equations, but you can do an experiment: Hold a chain in your hands. Fold up some of it in your hands and allow about as much distance of free chain between your hands as the free span of chain between your chainring and cassette. Pull it slightly tight between your hands - about the same tension as your derailluer creates on the chain when it's on your bike. Now bounce your hands up and down and feel how how much it pulls your hands together. The force you felt is more than twice the force that would've been created on your feet (because the chainring is not as large as the crank). This isn't the most accurate experiment, but it gives a rough idea of what could happen, *if* it even caused the hub to engage.

3. No, it does not make it impossible for the freehub to disengage. It simply adds another way in which the driver *could* engage, but engagement does not necessarily happen - and if it does, you just felt how little force is transmitted. Compare that to how much force your feet experience from smashing into things on the trail. The chain bounce effect is not large. As Steve mentioned, if the top run of chain slams into the chainstay or a STFU Chain device, the force is reduced further.
  • 2 2
 @R-M-R: The video or (2/3 of it) is clearly not about an effect Steve thinks is irrelevant. It even concludes with him stating that this effect is abig part of why ( high antisquat) suspension works better without a chain. Add to this, that even pros lock up their rear wheel quite often as traction is all but constant on rough ground, it is obvious that high kickback numbers are not neglectable.
  • 2 1
 @optimumnotmaximum: I'm not talking about a locked wheel. Yes, that causes serious kickback. I'm talking about coasting and about the chain bouncing up and down.
  • 1 1
 @R-M-R: "Add to this"
  • 1 0
 @R-M-R: I don't think there's any real significant kickback (ie trying to rotate the cranks) from chain bounce per se, because for that to occur you need high acceleration of the chain AND for the freehub to not be overrunning, which it almost always is. What some basic calcs (which are based on plenty of assumptions + some measurements, so no guarantee here) show though is that once the chain tension vector becomes sufficiently large in magnitude and/or deviates significantly far from the typical "straight" chainline we use for pedaling calcs, that it can actually start having a pretty significant effect on suspension motion because of the suddenly increased moment arms it can generate, along with significantly high tension forces in BOTH top and bottom lines of the chain (ie acting just to pull on the axle or front triangle, not specifically to rotate the cranks or wheel). There's a good discussion of it in the comments on the YouTube video already.
  • 1 0
 @VorsprungSuspension: Not disageeing with that, just looking to explore the relative contribution. An impact that causes such a curvature in the chain also creates quite the acceleration on the suspension and at the rider's feet. The STFU Bike video provides a nice empirical look into this, albeit not in the extreme case of a bike with elevated chainstays.

www.youtube.com/watch?v=9N2RvBO9HeY
  • 1 0
 @VorsprungSuspension: Ah, I was still in kickback discussion mode there.

Good discussion with Seb, as always. I see your point on the influence on suspension motion, but it seems like such a brief, transient effect that it could be lost in the noise, including during the period when the tires are loading up and compressing. The force acts over a pretty small distance and duration, especially if the chain motion is partially restricted by the upper run hitting the chainstay and the lower run being restricted by a clutch mechanism, and the total energy is small, relative to other inputs. Not saying I disagree, just that the mentioning of this effect has caused it to be over-represented in the mind of readers / viewers.

Thankfully, the effect is easily testable, albeit qualitatively, via the absence of a chain, turning the clutch on and off, supporting the lower run of chain, etc.
  • 1 0
 @R-M-R: for sure, it certainly isn't the biggest factor affecting suspension performance, the impulses just aren't that large even when the forces are high but the effect seems large enough to be noticed by quite a number of riders, which may be a noise/structural vibration concern as much as an actual force directly acting on the rider (although the same can be said of a lot of vibration through the bike that the rider perceives as harshness, and some of those are vibrations we HAVE directly measured - www.instagram.com/p/Bylp_j5nfTV). It's just another element to consider in the relative chaos of mountain bike suspension performance.
  • 1 0
 @VorsprungSuspension: Re: Accelerometer(?) data: Neat.

Any insights into how non-linear the "pain" response is, w.r.t. force or how to identify and optimize comfort from the data? I'm assuming it's primarily a function of maximum force. Understandable if any conclusions are proprietary information.
  • 1 0
 @R-M-R: seems to be a function of frequency almost as much as amplitude, you basically need a PSD to show you where the damage is being done. There are large studies on the human response to vibration, far more comprehensive than what we've done, but the ones I've read have also only been 1dof vibration, not the 2.5dof you get with a bike.
  • 1 0
 @VorsprungSuspension: Interesting. Have you found the data to be actionable or were all the existing principles of suspension optimization and trial-and-error wisdom of bike set-up already on the right path?
  • 1 0
 @R-M-R: actionable yes, but probably not in the ways you're expecting or anticipating. It just starts asking new questions rather than validating answers to old ones. For example - if you're seeing about as much vibration horizontally through the bars as you are vertically, do you keep trying to isolate vertically or do you look at what's never really been investigated regarding reduction of vibration in the horizontal dimension? So for us, the actions so far are investigating things like that and trying to work out where the biggest gains are to be made. Not just a matter of "turn the Vibration Harshness adjuster 3 clicks counterclockwise" unfortunately Smile
  • 1 0
 @VorsprungSuspension: Awareness is the first step, even if we don't yet know what to do with the information!
  • 5 0
 rig a bmx free coaster to the crank to chain ring interface so you can back pedal quickly and disengage the ring from the crank. This would allow the chain ring to move independently for chain growth. In theory the chain might bounce less and suspension would be more free to move in that your drive force on the pedal wouldn't play a factor until you pedal quickly and re engage the free coaster. The clutch derailleur also wouldn't play into a factor in the chain would be rotating on the pulley wheels vs being locked in and suspension fighting the clutch. Food for thought
  • 2 0
 You could also replace a cassette spacer with the smallest cog on the cassette and than just use the derailleur to push it on there
  • 4 0
 There was an article thst included Gee Athertons makeshift version as said above. Empty spacer to allow chain slip thst he shifted into.
  • 1 0
 You’d need a better design than a bmx freecoaster. You can put in a quarter turn of the crank before the freehub engages which would obviously be a problem for downhill / enduro when you go to pedal out of a corner and you’ve got no pedal pressure.
  • 1 0
 @thenotoriousmic: look up the planetary freecoaster.
  • 1 1
 @deathgrip01: that still doesn't solve the issue because the chain growth comes from bottom derailleur pulley to chain ring. the dead cog would be ineffective. If we put shimano's new xtr clutch into the crank or a shiftable disengagement system into the chain ring so the chain ring can spin independently from the crank in rough terrain that would be the key. A system like Hammerschmit from truvative but the shift operates a crank clutch to truly put it to nuetral
  • 4 0
 The clutch on the shimano makes a real difference when it is on and when it is off on the rear suspension,finding the right balance isn’t easy ,and yes that pedal kick is very noticeable when going down a steep put some rear brake and turn ,it’s like your chain got stick for a moment and your pedal doesn’t want to go down for a moment ,but nothing real serious like so many people talk about it ,I think it’s more just deal with it thing ,and yes the noisier the bike the more you think you are going fast ,and can make you feel like you are pushing it too far ,and then brake it is
  • 8 0
 When your pedal doesn't want to go down - that is because your brake is locked on..
  • 2 0
 Back when I used to run shimano I used to run a chain guide and take the clutch of for that reason. The drag through the shifter massively increases with the clutch on.
  • 1 0
 @thenotoriousmic: I wonder if new Shimano does this? My kids 11sp XT really increases the drag like you say. Its massively worse than SRAM's clutch. I can tune it back but then I'm doing a dance between a tight chain that stays on in a big send...and a loose chain that pedals easily.
  • 2 0
 @Svinyard:

This is why full trap chainguide with non clutch derraileur is besr
  • 1 0
 @getsomesy: They always scrape and will they even work with eagle cassettes? I’ve never dropped a chain using srams x sync chainrings and srams clutches don’t cause a massive amounts of resistance through the shifter.
  • 1 0
 @thenotoriousmic: Yeah the issue is more on the Shimano side. Crap clutch. Its like a draggy brake. My Eagle is fine. I'm sure the new Shimano stuff is a big step up in the clutch side of things tho.
  • 1 0
 @Svinyard: looks like the same clutch design.
  • 8 1
 That why the future is with gearboxes and belts, Right ?
  • 4 2
 Wrong
  • 1 1
 Realistically, bike drive belts are almost as stiff as chains, so you won't gain there. And if you've got a bike with typical AS, you'll get the same kick back (and it still needs some sort of spring tensioner)
  • 1 0
 @mountainsofsussex: But gearboxes have a freewheel in the crank, so wouldn't that eliminate kickback?
  • 1 0
 @deathgrip01: depends on the gearbox, I think the effigear one does, don't think the pinion does. But that just affects the engagement angle, doesn't affect the chain pulling on the cranks.
  • 4 0
 This makes a really good case for using chain guides that sit on the top of the chainstay like chris kovarik's stfu or a chain tamer.
  • 2 0
 @VorsprungSuspension: Very interesting thanks. The effect Im interested is what happens when descending, not pedaling but breaking and what impact the relative position of the break caliper to the axle line has. When breaking there is a force transmitted from the wheel into the frame as its slows the wheel. If the caliper is behind the rear axle line then that force is effectively trying to lift the rear wheel and swing arm as it pulls on the frame through the brake mounts. If the caliper is infront of the axle line this same force will be pushing down on the caliper and thus swing arm effectively trying to push the rear wheel and swing arm into the ground. I guess my question is how significant is this and what impact does it have on the kinematics of the frame compared to the impact of chain forces?
  • 1 0
 The couple moment on the swingarm will be identical no matter where the caliper is oriented (like whether you have the caliper mounted at the top, bottom, front or back relative to the axle) and the tractive force acting horizontally through the axle will be identical so the net result is unchanged. Draw a free body diagram and you'll see what I mean.
  • 1 0
 @VorsprungSuspension: If the wheel is rotating the calipers are resisting that rotational force from the wheel. At each point on the wheel. If the caplier was level with the axle infront of the axle the rotational force from the wheel is straight down. If the caliper was level with the axle be behind it the rotational force at that point is straight up. Will this not impact on the swing arm as the forces are in opposite directions at those points.
  • 2 0
 When pedals are weighted so they can't turn, and you hit a bump, and your freehub engages, anti squat spikes and your swing arm is unable to move completely freely until your hub disengages. This all happens in a second. So for us amateur riders, don't worry about it.
  • 5 0
 Physics, am I right?

xkcd.com/793
  • 2 1
 Thats a total gem (despite the poor audio). I think i finally understood whats the problem and whats not, gotta love Vorsprung Steve keep it up ! For me it also finally explains why clutch deraillers always felt weird and why 0chain might actually work.
  • 2 0
 Funnily enough I don't think that the Ochain system will actually do anything really, because the issue (when coasting) isn't so much crank rotation as it is actual suspension motion interference.
  • 1 0
 @VorsprungSuspension: In your video you said that all the chainextension due to chainslap has to come from the back as the crankspider is fixed, so i thought it might be beneficial that with 0chain the spider is actually allowed to rotate backwards and supplieing chain. but hey physics was not my best subject in school.
  • 1 0
 @optimumnotmaximum: it might help marginally with that - I don't see it being something that's actually significant or noticeable beyond placebo though.
  • 2 1
 When I lived in Whistler, my chain broke and instead of fixing it like anyone else would do, I stripped off the rear mech, cassette and shifter and did most of the season like that. Hands down the best riding I've ever done, so quiet, and the need to pump off every downslope to maintain/gain speed really improved my riding. Only downside was I was always the last one to get the top of Dirt Merchant from the lift!
  • 2 1
 This introduces some other factors. Removing the weight of a derailleur, cassette, and chain allows the suspension to work more freely without all that weight to slow it down (higher ratio of sprung:unsprung mass). In this case, the suspension is working better primarily due to the reduced mass at the wheel, not kickback effects - and, as you mentioned, the silence is wonderful.
  • 2 0
 For what little bit I was in Whistler, that race up to Dirt Merchant got less important as the day went on & brains got foggier with exhaustion and Beer
  • 1 2
 @R-M-R: Factors only if lighter is always better.
Which, it's not.
  • 1 1
 @R-M-R: @xstrongyx same happened to me, its really a balance of everything...a drivetrain really does hinder a bike with all its noises , sprung mass and friction!
  • 3 0
 @OnionRing: All else being equal - strength, stiffness, durability, damper performance, etc. - then less *unsprung* mass is always better.
  • 1 0
 @VorsprungSuspension can you comment on the perception of or reality of the chain being on anything to forward momentum when the bike hits things like ledges or rocks? I can feel a more sensitive suspension when my chain is off aure, but I can also feel the bike slowing down without any forward pull from the pedals & chain engaging as you hit big stuff. I've always insisted I can feel the bike accelerate due to pedals engaging the chain & rear wheel as the bike hits sharp objects. That can't happen without a chain. I am fairly certain that a track like Val di Sole that has tons of momentum stopping shelves and potholes would slow the bike down without having a chain on. Sure, your suspension is free to move more easily but the impacts on certain courses fights your forward momentum. With the chain on, hitting ledges, shelves and potholes you're landing hard on the pedals & turning the wheel with every landing to override those compressions. Right?
  • 1 0
 If we're coasting and not pedaling, hitting bumps (defined as a profile raised ABOVE the straight-line trajectory of the bottom of the tyre, assuming the bottom of the tyre is also travelling parallel to the centre of mass, which on average it is) will only ever slow the bike down. This is dictated by the conservation of momentum laws - you can't apply a force to the wheel with a backwards (horizontally speaking, horizontal in this case being whatever the ground level is) component and have it accelerate the bike forward. That'd be like me sneaking up behind you and shoving you forwards except you break the laws of physics and fall backwards towards me. The lower the force component is, the lower the deceleration. What's happening internal to the vehicle is only relevant insofar as it affects the amount of radial force generated through the wheel there, so the more freely the wheel can move out of the way of impacts, the lower the decelerating component of force. This is relevant at any frequency above which the rider can anticipate and react to lift the bike up, so things like rocks, braking bumps, or any kind of repeated bump at speed. If your chain was actually engaging the rear wheel on impacts like this, it would slow you down NOT speed you up (this doesn't mean you'd be faster OVERALL without the chain... just in this specific scenario).

However, the reverse is also true - if you're pumping through a depression where the ground level is fundamentally dropping away from the trajectory of the bike (a quarterpipe is a massive version of this), the more force generated, the faster you'll come out. Imagine even rolling off a kerb VERY slowly - as the wheel rolls over it, the force generated on the back side of each wheel will accelerate you forwards.
  • 1 0
 @VorsprungSuspension: Man...I can understand that theory on the compression end of an impact, but once you land off a flat huck and the suspension extends, all that energy transfers vertically into the rider. It won't result in a transfer that makes the wheels turn forward. WIthout the chain, if you land off a loading dock, you bounce back up and that's it. But if you land off a loading dock with a chain, sure, the chain and "locked" wheel resist the compression and therefore momentum, but then that stored energy results in the chain pulling the wheel in a forward direction. I even watched the slo-mo huck video from Pinkbike from earlier.
You can see the bike land and torque from chain takes a minute to pull the wheel, but it does. The trick being that the bike's got to be in a pretty small cog to amplify the force.
  • 1 0
 @VorsprungSuspension, one thing I can't get my head around: Thinking of a split pivot bike, which can be thought of as a single pivot bike (because it essentially is) or as a specil case of a horst link design with the rear axle and horst link concentrical. If I draw the IC (which still should be valid), the IC will end up at a different place than the main pivot, also resulting in a different (usually lower) anti squat and anti rise. How can this be?
  • 4 0
 You will learn to ride better without a chain though!
  • 8 0
 Don't think so,got a 13 km road ride to the trail
  • 4 0
 If gwin had no chain at all he would of slowly rolled out the start gate and finished 10 plus ! He actually had a chain for few seconds to get him out the gate !
  • 1 1
 Is not a pivot concentric around the bottom bracket the best location for this reason?

I have 1999 Cove G-Spot and i'm surprised more bikes don't use the design.
I guess its more complicated and requires more maintenance.

Thanks for the tech.
  • 1 1
 If that's the only pivot or if there are no other pivots between the BB and the rear wheel, the pedaling anti-squat is extremely low and the bike will be very squishy when pedaling. If there are other pivots between the BB and the rear wheel, it's possible for such a design to work well, but not *because* of the BB pivot.
  • 1 0
 Lenz MilkMoney with Concentrak pivot
  • 2 0
 BB pivot has lots of pedal bob as rmr said and the axle path hasn't got any rearwards movement, so it ain't good for pedalling nor dh. Great for single speed slope bikes though.
  • 3 1
 Not the conclusion of the video Wink
  • 1 0
 So, if you have one of those old school chain stay tensionsers will that help mitigate some of the downward inertia on the chain, and if so, what would the trade off be?
  • 5 1
 Stfu bike
  • 2 0
 @kleinblake: Yes, I heard those are really good, but the original ones hung beneath the chain stay, those are the ones I am referring to.
  • 2 1
 this also explaines why this new italian elastomere crank thing works, it hinders the chain from reengaging the freewheel -nice
  • 3 0
 Is this why the GT I-drives worked so well..... until they broke that is?
  • 1 0
 IDrive was great and mine didnt break. It sure wore out bushings quickly on the shore though!
  • 2 0
 Still remember this GT ad from years ago. youtu.be/2bNDBGww1wg
  • 1 0
 It depends, maybe the chain gives more progressivity to the suspension and is better even if "working less". Think Gwin would have won with a chain too
  • 3 0
 Waiting for the brand new AXS chainless transmission
  • 1 0
 What's up with the seat positioned way forward on the post? I can tell you don't think your bike rides well without any further description.
  • 2 0
 Not my bike in the video, but that's what anyone does if they want an effectively steeper seat tube angle, particularly on steep climbs. Every one of my bikes ever has been set up like that as well, because STAs are still generallly too slack for tall riders.
  • 4 6
 FFS, can we just change all bikes to the following suspension arrangement right now?

Put a single pivot in a place that balances the tractive force against the CG to accomplish 105% AS without taking chain tension into account.

Run a bottom bracket that acts as a jackshaft through the centerline of said pivot. A chainring on each side. One has a chain to the cassette, the other to the crankset.

Go one step further and put a geared hub on there, no tensioner needed as there will be zero chain growth.
  • 3 0
 @C0yotekid:
If I read correctly, the starling DH bike would be a prime example if this. Right?
  • 2 0
 @stab0905: yes, the Starling is a prime example. Why not on trail & XC bikes too?
  • 12 3
 This comment reads like a 10 year old that's read one 'technical' piece and thinks they know everything about suspension design.
  • 1 1
 @UtahBrent: Aren't single pivots really prone to brake jack?
  • 1 0
 @C0yotekid: ...or heard.
  • 1 0
 There shouldn’t be a tensioner needed anyways, right? That is what the derailleur is for? Or are you saying a tensioner between the chainring and the pivot-ring?

Also, a gearbox of the right design that has its output concentric to the main pivot could eliminate the need for the intermediate chain entirely, right?

Packaging would be an issue though, and the design of the gearbox would have to be done in conjunction with the bike design.

In any case, for a singlespeed I think the starling has the right idea. I’d like to see an enduro bike with the same concept
  • 5 1
 +1 to jackshaft

Now if only I knew what a jackshaft is...Regardless I'm positive that Dick Pound has one.
  • 1 0
 geared hub on the back is bad, i have been saying it, just build a modern version of the honda g cross with that capuseled drivetrain that someone ( i think shimano) patented a couple of months back.
  • 1 0
 wow i really enjoyed the visualisation of pedal kickback. never had seen it so clearly before! cheers @VorsprungSuspension
  • 2 0
 Steve is quite a looker with this new haircut!
  • 1 0
 @VorsprungSuspension Please keep these coming, and please keep making them more and more technical each time
  • 1 0
 Your suspension works better with a hub that doesn’t use a pawl system too. Mine’s Onyx.
  • 1 0
 Holy sh*t that was hard to follow
  • 1 0
 I'd venture to say it works better because there is no chain
  • 1 0
 It works better because of how much better it works.
  • 2 1
 Who knew explaining a bad suspension design is so hard!
  • 1 0
 i was looking at a demo without the chain itself....
  • 1 0
 Is that an old prototype Nomad?
  • 1 0
 Is that calculation based on flat earth gravity?
  • 1 0
 There is no such thing as gravity !)
  • 1 0
 Perhaps I missed it, did he talk about why bikes have idlers?
  • 1 0
 Definitely give up pedaling efficiency though..
  • 1 0
 What's with the sentence chop editing!?
  • 1 0
 Too bad he used my bike in the demonstration...I guess my bike sucks...
  • 1 0
 The bike definitely feels better
  • 1 0
 Lets all go moto style & have foot operated rear brake!
  • 1 0
 Brilliant video Steve.
  • 1 0
 TLDW??
  • 1 0
 Jeez. I am a dummy.
  • 1 2
 Unsignificant influence

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