Opinion: Carbon and Aluminum Wheels - Does Stiffer Always Mean Better?

Mar 6, 2019 at 1:41
by Matt Wragg  
Header for Matt s Op Ed pieces.


Versus can be such an ugly little word, especially in bike testing. The problem is that it demands absolutes, that the world be divided into black and white, yet as you start to get more of a sense of how a bike could and should work you begin to understand that we are working in shades of grey. So I don't want you to read this story as aluminum versus carbon, and if you are looking for a clear cut answer I can save you some time and tell you right now that I don't find one. Rather, this is a small experiment to test the conventional wisdom and try and figure out what works best with my bike, for me. The hope is that me working through this will get you to think about what components you choose, and why.

A Brief History of Stiffness

This story was worth writing for that sub-heading alone, right? Before we dive much further in here we need to cast a glance back across mountain bike history. What many of you may not realise is that compared to a few short years ago, we are now in a golden age of mountain bike technology. Anyone who rode in the '90s will tell you that the idea that a solid 95%+ of products on the market being structurally up to the task is huge progress. My first riser bar was a Club Roost Go Fast bar (maybe it was called something else, all I remember is that it had "Go Fast" etched into it). The other thing I remember is that it needed a brace across the middle to keep the two sides properly joined together. It is a mark of progress that many of our younger readers probably can't even imagine riding with a wobbly handlebar, but back then we accepted it and told ourselves it looked more moto like that...

The same goes for the rest of the bike; frames and forks flexed, wheels bent, seatposts snapped. I don't think you could pay the modern World Cup racers to take to the slopes with the original 32mm-stanchioned Boxxer. You don't tend to see frames smeared black around the stays where the wheel and frame made contact under load. It was a big engineering challenge, one the industry rose to meet admirably. What this meant is that for much of mountain bike history, stiffer meant better. It was a good mantra. It worked. The problem is that today things are so good that it is no longer true. Unless you are buying inappropriate kit for your riding, you rarely have to consider whether your components will be structurally sound. It is a given that it will be stiff enough and that mantra is now out of date. The problem is that this next step in bicycle evolution isn't as clean cut. "Appropriately stiff" is a much shittier marketing line than "better." It is much harder to talk to consumers about compliance and feel, especially when you have spent the last twenty years telling them that stiffer = better. But I believe that is where we are today and those are the conversations about bikes we need to start having.



Sospel France. Photo by Matt Wragg.
My Orbea Occam TR...
Sospel France. Photo by Matt Wragg
...the Scott Spark that replaced it.

My Personal Stiffness

Don't get me wrong, I love carbon wheels. I rode shitty bikes for enough years to love the warm glow of satisfaction in having a bike that is almost all carbon and ridiculously light. Even as a bitter industry cynic, I never get tired of having great bicycles to ride, it is a privilege that I could not afford if I did anything else for a living. I love the menacing deep sections, the zip of acceleration that you only get with a couple of thousand dollars-worth of wheels. So it was only natural that when it came to build my bikes I sought out carbon wheels. For a few years I ran the Ibis 741 then 941 wheels on my bikes and the wide, fat profile and the low weight felt great.

The problem started when I changed bikes. I had been riding an Orbea Occam TR and it felt good. I didn't spend too much time thinking about it, the bike just worked and I had fun. When I replaced the Orbea with my current Scott Spark I started noticing something (I wrote quite a bit about how I set my Spark up last year). My new Spark was a noticeably stiffer frame, much more direct and pointy than the Orbea, but I was struggling for traction. On off-cambers and hardpack terrain the bike was skittish and I found it hard to hold a line. This lead me to start to think about what I could do to find more traction, I didn't want to play too much with fork setup or tire pressures and casings as I had found a setup that worked for me; I really liked the way the frame felt and the shape of it, which left me looking at the wheels.

Sospel France. Photo by Matt Wragg

Sospel France. Photo by Matt Wragg
XMC 1200s
Sospel France. Photo by Matt Wragg

Sospel France. Photo by Matt Wragg
XM1501s


Testing

To make the test useful I needed the closest I could find to direct equivalents - wheels where the main difference was only in the material used. This lead me to DT Swiss and their XMC1200 and XM1501 wheels. Both are designed by the same people with the same style of riding in mind, and they share the same hubs, spoke count and inner width (30mm). The XMCs do have slightly fancier spokes, but other than that they are as close to direct equivalents as exists in the market today. One thing I did realise when putting both pairs under close scrutiny was that the weight difference was much smaller than I expected - around 100g per wheel, some of which can be attributed to the lighter Aerolite spokes on the carbon wheels. I will say that on the trail the weight difference did not make a big difference for me.

With both sets of wheels mounted up with my preferred combo of Schwalbe Magic Mary on the front and Rock Razor on the rear, I headed up to Viola St Gree - a little gem of a bike park in Piedmont that boasts a pair of incredible blue trails that would be a lot of fun to session on my Spark.

Before riding I checked the tire pressures to make sure they were at my preferred 23/28psi setup. I then did a couple of laps on each set then switched wheels and carried this pattern over ten laps, using the afternoon laps as my timed tests. It came down to the final two hot laps (on my final lap we stopped to take photos) - the first on carbon, then a final hot lap on the aluminum. Looking back, I can see that my heart rate ran higher on the second run, but I tried to be as consistent as I could in putting down the pedal strokes and I'd put that difference down to getting caught up in a good lap.

On the carbon rims I felt faster where the going was easier, I cannot deny that - there is nothing like the feel of railing a smooth berm on a good carbon rim, there is an incredibly positive feeling of drive that the aluminum could not match. Yet as I got further into the 7 minute-plus run, I was starting to feel a little beaten up, there was quite a lot of chatter being transmitted back to me and when it came to dusty, hardpack off-cambers I was struggling to get the bike to hook up.

Sospel France. Photo by Matt Wragg

The big difference with the aluminum rim was in the smoothness, there was an immediately noticeable difference in the ride, everything felt a little more fluid. While the feeling in the berms was good, it just wasn't that same driving sensation. On the off-camber sections where I was struggling for grip on the carbon rims I was finding it easier to hold my lines, and there was a very definite improvement in overall grip. On the long, five minute second main sector of Ottovolante (OV Sector 2) I was flying on my final run - that reduced chatter and additional grip makes a big difference when you are a few minutes into a trail, and I felt like I could ride harder for longer. The one caveat here is that on my timing I dropped four seconds to the carbon rim on that sector, however that can be explained away because a rider pulled up in front of me in the middle of the trail metres from the finish. In that instant I may not have been the courteous trail user I like to pride myself on being as I knew I was on for a good time. I felt even more stupid afterwards when the gentleman came over to me in the carpark to ask if I was ok... Still, on the timing sheet I only dropped 4 seconds, despite losing more than ten seconds to that incident. On the Ottovolante pt1 segment, I came out 19 seconds up compared to my time on the carbon rims - 4:49 vs 5:08 - even with that stop.


Sospel France. Photo by Matt Wragg


Conclusions

If you're waiting for me to use the word "better" or tell you which one to buy, I'm going to disappoint you here. For me, for where and how I ride, this test has convinced me that I should stick to aluminum rims on this bike. With a stiff frame like my Spark, the reduced fatigue and improved traction of the more compliant rims work - it has eliminated that skittish feeling that started me down this road and put into sharp focus the difference in trail feedback between the two wheelsets. The problem with me reaching this conclusion is that I do not believe it can be generalised - my Orbea was great with carbon rims, maybe your frame will be too. I have a Specialized Stumpjumper Evo in aluminum coming and this has convinced me to go through a similar process for that bike as I'm curious to know if carbon wheels will complement the (in theory) more compliant frame.

This test has lead me to believe that we should be looking at our bikes as systems, not collections of components, but that poses a huge challenge to both consumers and the industry. Unless you are happy to trust that bike companies know what they are doing in terms of overall system feel with their OE specs, how do you go about putting together your bike as a system? And how many of us don't love customising our bikes to make them our own? As a writer for Pinkbike I can phone DT and ask to borrow €3,000 of wheels to test a theory, but how many consumers are in a position to do that? At the moment there is no way to work out what frames and components work in what combinations to give the ideal level of compliance for a given rider, and I don't know how the industry would even start to address that. The other thing I am now certain of is that running down the road of "stiffer is better" is a dead end and the sooner that stops being an oft-repeated line, the better off we will all be.


278 Comments

  • + 211
 great article matt, really well considered and thoughtful. thank you!
  • + 60
 “I never get tired of having great bicycles to ride, it is a privilege that I could not afford if I did anything else for a living.”

>There’s this profession called “dentistry...”
  • - 27
flag hamncheez (Apr 5, 2019 at 7:53) (Below Threshold)
 @maxlombardy: these "dentist" jokes are getting really old. Dentists don't even make that much. A good developer will make more, and didn't have to sacrifice 4 years and a quarter million dollars of extra school.
  • + 31
 @maxlombardy: aw lawrdy i can't stop laughing. the joke that keeps on giving. DENTISTS AND THEIR DENTISTS BIKES... lawrdy make it stop.
  • - 45
flag ratm54 (Apr 5, 2019 at 8:17) (Below Threshold)
 @hamncheez: You are paied for school ? That's a good one ;-) If you pay for school, you are scamed ! French forever ! ( it works also for social security ;-) )
  • + 6
 Is not stiffness....the BIKE INDUSTRY new MARKETING term is "COMPLIANT", what she said!
  • + 7
 Agreed. I really enjoyed read. I fully support more of these types of articles and op/eds.
  • - 1
 Have you checkout stifler's mom?
  • + 1
 @maxlombardy: And another one called "retirement"
  • + 1
 funny to say all this about aluminum vs carbon now when for the last few years it was all carbon is better. better late than never.
  • + 4
 I also appreciated this article. After three decades on a wide range of (mostly 26") alloy hoops, I am now alternating between two sets of carbon wheels on my Slash. I'm an XL size rider on an XL size carbon frame and I've found my 40mm width wheels from Bontrager to be a bit chatter-y - what I have imagined that similarly-deep-section ENVEs would ride like. (I've ridden ENVEs just once but not long enough to form an opinion.) I'm also using a pair of CB Synthesis wheels which are far more - wait for it - compliant. I hadn't given a lot of thought to frame stiffness as a factor here. I am now curious about mounting up the Bontis to less stout frame to see how they perform. I really prefer the CB layup and tune.

Let's also acknowledge the 'fact' that the bike industry (like any other retail entity) is constantly pursuing new tech to push on us. That is, alloy wheels almost certainly suffice for 98% of riders the world round, but dentists and dentist-wannabes have fistfuls of dough to spend.

Give it time and we'll see graphene wheels (and Chinese knockoff graphene) before too long.
  • + 1
 Results are only valid with a nose-down saddle rotation of at least five degrees.

Literary reference: Princess and Pea.
  • + 5
 Not all carbon wheels are super stiff, like Enve used to be known for. Some are really compliant and smooth. Also, lacing and spoke count plays a huge factor.
  • + 8
 @hamncheez: Go ahead and downvote this but Hamncheez is dead on right.

(Yes, I'm going for neg props. gimme gimme)
  • + 3
 @maxlombardy: so, what if, the dentist is faster than you?
  • + 0
 There are other options to buying 2000$ carbon wheel sets. Like reusing your hubs and buying rims from LB. Used to be 150 a rim - pretty reasonable. Others are still in that range.
  • + 1
 @mattwragg - Now you need to test using Cushcore and Snakeskin tires with less psi on Carbon rims
  • + 1
 @sngltrkmnd: Interesting with the Slash 9.9 is they run a alu out back paired to a carbon up front. It is their top of the line race spec Enduro model. I wonder how that would ride compared to the carbon both ends 9.8 which I have.

Also tyres matching rims would make a difference be it type and size.

One thing I know, my Slash (full carbon) doesn't beat me up riding it as my old alu Radon Race XC hardtail with DT 1900 alu rims. That thing makes me feel like I have gone 20 rounds with Mike Tyson after a ride. It really sucks - by the way, anyone want a used Radon Race 8.0 2014 model??? Big Grin Big Grin
  • + 1
 @gnarterrorist: I believe the alloy stay on the race model was selected for durability rather than compliance.
  • + 156
 There's a general thing in sports that what is good for the pros is good for everyone. Loads of stuff stamps on it "Developed by our world cup race team" or "Developed with input from the Athertons"

But it's really not the case. For some people world cup tech is great. But for the majority of the MTB world it's not appropriate.

I am drawn to one James May who openly states that the Nürburgring has ruined many cars. They develop them to set the fastest times on that track possible so they have that headline figure, but ruin the dynamics for normal drivers, at normal speeds, on normal roads.

To further drone on I can also equate it to Badminton racquets. When I first played badminton I decided to get a Racquet and I wanted a nice one so I spent £50. It was good, it improved my play and I had fun. But N+1 applies to all sports and after payday one month I spent £150 on a racquet because I'm stupid. Did it step my game up by 3 times? 2 times? a little bit? No it made it worse. The sweet spot on the racquet was designed for a professional thus I could not effectively smash and the weight made it twitch rather than stable and methodic...

I digress of course.
  • + 40
 But was the Racquet carbon? Alum? Real Steel? A quick good image search shows me that most badminton racquets are surely out of round. I'd get yours trued by a professional asap.
  • + 4
 Wish I could prop up more than once with this statement. Applies to so many things. What is best for one is not usually the best for all.
  • + 17
 @Bikeordie1: I'm not really into racket sports but from what I've seen people typically smash them against the ground just before they argue with the referee. My hypothesis is that they start out round but when they're "pro tuned" they eventually go a bit egg-shaped. That said, I've never seen a table tennis player smash a racket (or bat as they call it) against the ground or even against the table, so this confirms my hypothesis.
  • + 54
 "A fast bike is often horrible to ride the majority of the time. It's really stiff, it's rough, it's kind of painful unless you are going race speed."
Rachel Atherton; today
  • + 2
 @Becciu: Yeah my Atherton comment was more to do with people like Shimano selling their pedals on the strength that they had input from Rachel.

Me and the Athertons require different levels of performance out of our equipment and I have considerably less skill to use that
  • + 7
 I agree except, most sports car owners will never take their car to a race track, where most DH or enduro cyclists will bomb their bikes down fast downhill tracks. So not really an apples to apples comparison. I think driving a race car on the street is silly, where you actually can go race your bike downhill almost whenever you please.
  • + 2
 @Becciu: Channeling my inner Atherton from now on.
  • + 3
 @gnarnaimo: And if they did take their car to a race track, without the skills associated with pushing a car to the limit where the suspension and damping makes sense, they wouldn't be getting the best out of it.
And like I say, some people will be able to get the best. But not a lot. It's good that World Cup level bikes are accessible to the common rider. Makes you feel good, and is great for Privateers who, short of suspension support, can really make an impression.
  • + 9
 @tufty: Fully agree. However, I feel because more dh/enduro riders ride fast and aggressive in comparison to sports car owners, I think able to use the bike closer to it's designed limits than I feel most sports car owners could with their cars.
  • + 9
 I think that can be taken further down the scale too. Journo's that are pretty good riders that spend their working day riding bikes opinion on whether a bike is good for me is hard to work out if that is right or not (basically have to pick the characteristics that I think suit me). I love it, but I'm much less experienced and slower than all my riding mates. I want stability and something that inspires confidence, not something that's "flick-able". I do something think it would be interesting to get a slow punters opinion and just see if what they think a good bike is and if it tallies.
  • + 5
 @rob-chambo: Problem I see with reviews is that most of them can't say bad things about the bikes. So you get a very wishy washy review that has no real world relevance.
There's a certain youtube review with many years experience and frankly his reviews have become cookie cutter. Always the same things said about the bikes.
It would be nice if there was a group of testers with different styles and tastes that you could acquaint yourself with and then have more faith in their reviews. But then if I spent all day, every day, testing bikes I think my fitness, and skills, would improve to a point where my reviews might become less relevant to the every day rider.
  • + 14
 @tufty: I dunno.. Have you read Paul Aston's ENVE review?
  • + 2
 @gnarnaimo: Link for the lazy?
  • + 1
 Yea, if car companies were really listening, we'd have self-driving trophie trucks that look cool but are super comfy and require no skll to drive. RIP manual transmissions.
  • + 1
 @gnarnaimo: And this is what we need in the Industry
  • + 5
 Such a great comment (re: your James May reference)t. This has been on my mind a lot lately. I think bikes have been super tuned for the fireroad-wide, bermed flow trails of today. Super long, ultra low, extra slack... it needs a special kind of trail. (Not that there's anything wrong with that). It does have an effect all all around abilities though.
  • + 1
 @gnarnaimo: I really hate asking this... but can anyone enlighten me on what happened to Paul Aston? Been looking for answers but all I see is RIP Paul - so confused.
  • + 4
 @tufty: Regarding the reviews all being similar comment:

You do occasionally see products and/or bikes get roasted. I've definitely seen a lot of cheap tires roasted on completes (reviewers changed them out straight away because they're trash), outdated geometry normally gets called out, bad saddles and grips, suspension that isn't up to par etc.

Most medium-high end bikes tend to get similar comments because they're basically all pretty good and often all pretty similar. I can't think of many bikes from the mainstream companies that are genuinely, objectively bad. Bike companies know how to make something that is going to behave pretty well. A lot of companies just follow industry "standard" numbers with tried and true suspension platforms and then update them as fashions change. It's very hard for a bike like that to be bad and all the reviewers can really do is comment on the quality of construction, the build kit and give pretty generic feedback about the ride.

When a company does something different, like uses a new suspension design (nalid react 2 play is a new one) or does something interesting then you get some more interesting reviews and feedback. But most bikes are just super similar and all pretty good.
  • + 4
 @iduckett: RIP PAUL WALKER
  • + 1
 Was the racquet made to DUB standards?
  • - 1
 @tufty: I AM THE LAZY. what you talkin bout willis?
  • + 2
 @iduckett: He left Pinkbike though some of his reviews are possibly still in the queue.
  • + 2
 @usedbikestuff: Got to love you. I am so lucky that my wife and I only want CARS, and they have to have manual transmissions. Carbon verses aluminum. Just don't get sucked in and break the bank with carbon.
  • + 2
 The important thing is...do you say bad-min-ton...or bad-mittin
  • + 1
 @gnarnaimo: gnar naimo. hahahaha. funny name.
  • + 1
 @jamesbrant: Just remember where you saw it first Wink
  • + 1
 Your story translates well to MTB

You don't want a Badmountain day (badminton)
  • + 2
 It all depends. I saw very noticeable gains going from narrow aluminum (19mm internal) to wide carbon (26mm). The stability and weight savings dropped a ton of time off my climbing and descending.
  • + 1
 I’ve never played racquetball, but in Ping Pong the cost/benefit is massive; but only for players good enough to take advantage. The same goes for cars and bikes, imho. A great driver could beat a Ferrari in a Ford Escort.
  • + 2
 @hangdogr: Couldn't agree more with this statement . New bikes are being tuned more and more to this type of trail/riding style. Great if you have trails like that. Unfortunate if you don't (I don't). What I also find unfortunate (and perplexing) is that no one seems to admit that bikes tuned for that type of riding inevitably give up a lot in other areas such as agility, weight, pedal strikes and low-speed handling.
  • + 1
 @Climbtech: My counterpoint is that bikes are being made faster, safer (by virtue of slacker geo), a stiffer - and this is a boon for the customer. Sure, not every trail rider needs a Trek Slash or a Pole Machine or a Transition Sentinel. But that these options even exist, and can function as many riders' go-to trail bike is a pretty darn good thing. We're in a golden age, IMO. "There are no bad bikes" is a common refrain amongst my friends. (Ok, that Fuji Auric looks pretty noodly.)
  • + 2
 @sngltrkmnd: Faster in a straight line, downhill. Faster pedalling than the previous generation of mid and long travel bikes. I guess that good for the customers, especially those new riders who don't know how to ride yet? Safer is arguable. Is it safer to have a newb screaming mach-chicken down a DH course when they don't know how to turn?

Regardless, "faster" isn't the only feature of a bike I'm interested in, which is kind of the point.
  • + 1
 @hangdogr: Fair 'nough. There's a heap of nuance to the generalization 'faster'... but another way I like to look at it is that if I were new to the sport today, I'd be pretty excited. So many of the kinks have been worked out, issues that I've witnessed or experienced over the many years I've been riding. Squeaky pivots, short/tight/cramped geometry, open dropouts, squeaky suspension components, flexy frames, hard durometer tire rubber, narrow bars, rim brakes, various incarnations of unreliable travel adjustments, over-leveraged suspension designs, bottom brackets from BMX bikes, saddles and handlebars inspired by MX bikes, etc.

As far as safety, a longer/slacker/lower bike is just as dangerous in the hands of an inexperienced rider as a 90s URT bike with rim brakes. That'll never change.
  • + 1
 @sngltrkmnd: I agree that diversity is great, and for those that want and can use them, bikes like you cite are better than anything before them and it's good they exist. However,options and diversity are useful to the consumer, and I would like them to remain -- don't just change the reach to 500 and HA to 64 (and by next year I will mean 520 and 62...) on every bike model and call it "progress". For some of us, that's not what we're interested in.
  • + 2
 @Climbtech: The longer/slacker/etc geometry has been out there for a good while, but it was limited to the pro athletes. They got a different rocker in the linkage or something. The Iron Horse Sunday Sam Hill used to ride was modified, the Kona Fabien Barel rode was even very heavily modified. Back when the Athertons were riding for Commencal they were experimenting with really long and slack geometries and Gee liked those a lot and that's what he got to ride. But for production, they toned the geometry slightly to suit the Commencal staff who are already proper shredders in their own right. Just to get the same thrill but actually at the speeds you're going as a properly fit and skilled end consumer (who is still nowhere near the level of Gee). It seems journalists weren't accepting that anymore and praised the brands who sold their bikes exactly the way their pros ride them. So that probably changed the market. Still, I think Cube still tones their geometry down a bit to make it more suitable and fun for the end consumer. Just like cars. Mike Levy can probably have more fun riding his car at 80km/h than someone in long and stable Mercedes at 120km/h. Ex-pros and other professionals aren't necessarily the best at tuning consumer level bikes. Just like adults aren't necessarily the best at deciding what toddles would find fun. Not meaning to compare the regular end consumer to a toddler but I hope the point came across. I expect it will settle or even reel back a little in the next couple of years. Actually for me this is what I like about riding a hardtail and standing up. The bike comes alive like that and becomes a fun challenge at lower speeds. The speeds I can get away with crashing.
  • + 1
 @vinay: Thank you for the history lesson. I quite enjoy learning/reading about how things evolve. Interestingly, in the newest Syndicate video "The Syndicate + Fox Suspension - How We Work", Jordi has the best comeback when asked why the public can't have the same suspension and settings as the DH pros. He replied, "Ok, I'll take your bike, and set it up just like Loris', and that's how you will have to leave it for the year." I think it's very similar to the geo argument you make above.

Race bikes are better than ever, but not everyone wants a race bike. I just hope the manufacturers reflect that in a diversity of offerings.
  • + 0
 @Climbtech: this is why I love my kona 153 so much, still has a steep enough hta to make agile riding fun with enough length to make it reasonably stable
  • + 71
 I welcome an article that discusses the pros/cons of carbon and alloy rim materials. But I have no patience with articles that pass themselves off as pseudo-scientific because they employ "experiments" such as timed runs and make an effort to be consistent on some variables (tires, psi, etc). Those "controls" are mentioned, yet the author makes no effort to even define the term that his entire article is based upon? What, exactly, is this "stiffness" that he is supposedly feeling and judging? Vertical deflection? Lateral deflection? Tangential deformation?

Far too many riders falsely imagine that alloy rims have more vertical compliance than carbon rims, that they "conform" better to trail chatter, and that this explains the difference they feel (or perceive they feel). The well-documented reality is that any properly tensioned bicycle wheel, as a pre-tensioned structure, has so little vertical compliance under the vast majority of its use that it is indistinguishable. Generally speaking, even under a high load event, a typical alloy rim would have roughly 0.5mm of vertical deflection, while a similar carbon rim wheel would have 0.25mm of deflection. Meanwhile, the tire may have 25mm to 50mm of deflection. Kudos to those amazing riders who can distinguish the 0.25mm from the 50mm.

In my opinion, Pinkbike readers would be better served by an article that explains what "stiffness" really means in a pre-tensioned bicycle wheel structure, what variables influence the actual measurable attributes that constitute stiffness, and some (possibly subjective) discussion of how those attributes translate to ride quality/behavior.
  • - 9
flag clink83 (Apr 5, 2019 at 8:47) (Below Threshold)
 I guess the alloy rims that I have that hit the brakes (on my road bike) or the tires on my chainstay (mtb) have imaginary flex...
  • + 4
 Not to mention compliance in wheels is objectively bad. It detensions the spokes, which can allow them to loosen up over time and eventually fail if you don't keep an eye on it. Pros who only need their wheels to last for a race or two surely aren't concerned with that, but for those of us who care about long term reliability and ease of maintenance, it's best to look elsewhere for comfort and traction.
  • + 20
 @clink83: Nothing in my comment suggests that alloy rims won't rub brakes or chainstays. What you are describing is transferred lateral deflection. This can occur with both alloy and carbon rims. It is a function of both native rim stiffness and spoke system stiffness. Counter-intuitively, if assuming an identical spoke system, a less-stiff (alloy) rim will actually produce LESS lateral deflection at the seatstays/chainstays than a more-stiff (carbon) rim. This is because the more flexible rim "absorbs" more deflection at the point of load (the ground) without transferring it to opposite locations (like the seatstay), while a very stiff rim will transfer far more of the deflection from the point of load to opposite points. Think of the flexy rim deforming slightly like a potato chip at the ground, while the rest of the rim says "flat"; think of the stiff rim as a rigid disk that "tilts" from the point of load to the points radially opposite.
Sufficient spoke system stiffness (more spokes, greater bracing angles, thicker spokes) will counteract this transfer. The worst case scenario for rubbing brakes or chainstays would be a very stiff rim and a very low spoke count, thin spokes, on narrow flanged hubs.
Ironically, your direct experiences may be a result of the stiffness of your alloy rims, and the lack of stiffness of your spoke system, rather than your assumed explanation of the rim flexibility.
  • + 3
 Vertical flex isn't it. Of course a properly built wheel doesn't have much. Lateral flex is what you feel leaned over hitting a rock/rut in hard cornering. Or not leaned when one side hits a rock. Every wheel has that to a different degree.
  • + 1
 @Inertiaman: Love it. Well said. One of the most basic no-no's in research is using a construct without first defining your use of it and defending the significance of it. As a construct, "stiffness" is used all the time, however I would agree that as it relates to me on a ride this afternoon we assume we know what it means but in reality it has not been universally described in terms of ride quality and felt properties. So yeah- I would love to see a bigger discussion of what we are talking about before emotionally or objectively trying to rank things based on it.
  • + 8
 Mate, ain't no one got time for quantitative analysis and understanding, there are bikes to sell!
  • + 2
 The article is labelled as "Opinion" but it also has a section titled "Testing" which is kinda bullshit.
  • + 5
 While I agree Matt Wragg's efforts to be scientific weren't always well placed, I give him credit for trying. At least he's opening the conversation and presenting a counterpoint to the notion that carbon and/or expensive things are inherently better.

My main criticism is the implication that carbon rims are inherently stiffer and aluminum rims are inherently softer. We're starting to see carbon rims with very low section height, which could have less radial - and maybe lateral? - stiffness than many aluminum rims.
  • + 1
 @Inertiaman: they also will flex vertically. If you ever snapped a spoke at the J while JRA, that's from vertical flex.
  • + 2
 Fundamentally, do you want an entire system flexing—less predictable—or a more predictable system, I.e. very little flex in the system? For example, Would a super stiff bike with flexible bars perform the same as a bike with a compliant fork, frame, stem, and handlebars? My point is, don’t blame the wheels. The contact points affect suspension which influences comfort which results in faster times over distance. These contact point points are basically your hands (legs receive less unsprung forces). The 35mm standard and idea of stiff handlebars is dumb and only results in fatigue and pain... if you have a predictable wheel movement but a compliant handlebar setup, the result is better handling.
  • + 0
 @blackthorne: in a complex system like a bike, who knows. I defiantly prefer a stiff stem with a flex carbon bars, and very little flex in my cranks, but other than that there is a lot going on and I try not to over think it.
  • + 5
 @blackthorne: I agree bikes need compliance beyond just suspension and tires and I agree it's ideal to maximize comfort while minimizing the lack of precision and control associated with flex. My belief is that it's most effective to have the compliance concentrated near the ground. Flex that is concentrated a long distance from the ground allows this angular misalignment between the neutral location and the flexed location to propagate into considerable displacement at the ground - i.e. if we had 5 mm of flex in a handlebar, that translates to a lot of displacement at the contact patch, while 5 mm of flex at the tire is just 5 mm.

I agree the 35 mm bar clamp standard usually produces a harsh ride, but if I could get the same amount of additional flex from my tires or rims as with a 31.8 mm bar, maybe the combination of a stiffer bar and softer tire/wheel would be equally comfortable and more precise.

Another benefit of compliance at the tire or rim is that it's unsprung mass. A fork can react only so quickly; it's not efficient at handling the size and frequency of impacts that can be handled by a compliant tire and rim.

The design of a wheel and tire, such as rim shape, spoke bracing angles, rim width, etc. offer enough variables that we can address the cliché "laterally stiff and vertically compliant" objective. I agree with the objectives you've described and I think tires and rims are the most efficient way to get there.
  • + 3
 I didn't feel this article was attempting to be scientific, but rather to do some real world testing and get a rider's perspective. These are the sorts of things that bike companies do in addition to scientific tests.

WRT to vertical compliance in rims, is possible that additional lateral compliance in alloy rims is what's responsible for the preferable ride characteristics? How do you know that the difference of .25mm of vertical deflection is being absorbed by the tires? Have you done a scientific test?
  • + 11
 @b3n: No problem with the article's intention to contrast/compare rim materials, or discuss the subjective ride characteristics. But he's comparing lap times and making conclusions based on that, despite ignoring huge numbers of uncontrolled variables that would influence the outcomes. Pick your own nomenclature, but I don't think "false science" is an unreasonable description.

Lateral deflection (or lack thereof) is certainly a valid attribute that might explain some differences in ride characteristics. So why not measure it? Its not particularly hard to do.

As for the 0.25mm vertical defection number, that's direct math. Forgive me for not subjecting Pinkbike readers to the equations, but spokes are steel, how much it stretches under tension can be directly computed, the corresponding rim movement as that tension decreases can also be directly computed. Assumptions are required, so the number isn't exact, but the scale is. Whether its 0.17mm or 0.31mm doesn't really matter. Its the proportion of those tiny numbers to other variables that I'm pointing out. As for the 25mm to 50mm of tire deflection, that's simple: you can sit on your bike and a buddy can directly measure the "sag" from the tires at 5-10mm. Or consider a bottom-out event where the tire touches (or nearly touches) the rim; in that case, its roughly the tire cross section that deforms. Again, its not the exact number that's important. But there's no arguing that MTB tire deflection is ~ 100X the scale of rim deflection.
  • + 2
 @blackthorne: I did a ctrl+F for "System" across this page and your reply nailed it. couldn't agree more. I tried new 35mm alu bars that were horribly stiff even after upgrading my fork's damper and running a token for lower initial pressure. good old 31.8 carbon renthals + some high traction renthal grips solved the issue entirely.
  • + 32
 Stiffness needed is also based on the rider, not just the terrain. Someone who weighs 150 pounds requires a lot less stiffness than someone who weighs 225 pounds. These articles seem to always ignore that principle. Usually assuming everyone is the same shape and size as them. It would be interesting to see if they had someone who weighs 140, 180 and 220 do the same test and whether or not their feedback would change based on the stiffness required.
  • + 7
 I heard 20 years ago that mountain bikes are designed around 160-170 lb riders and I'd bet that that's mostly still true. Companies have to tune a build around some weight. If they pick a weight that's too high, then lighter riders just get a harsh ride. If they pick a weight that's too low, everything gets broken. Until manufacturers start making frames and components for weight ranges(cost prohibitive), things will still be designed around 160-170 lb riders.

3.0 tires on regular trails pretty much suck for lighter riders who have to run crazy low pressures in them. For bigger(200+) riders who ride 3.0 tires at higher PSI(15 or more), they're wonderful! I use this as an example because I'm bitter that Maxxis is dropping all 3.0 tires.
  • + 4
 @Explodo: 220lbs here. Love my 3.0" on the trail hardtail! 16lbs front, 18 lbs rear is perfect for me.
  • + 7
 Being as I'm 6'4, 215 I'm always skeptical of "durability" ratings since I'm way above the average size of a rider. I'd love to have a separate test group(larger folks), putting bikes/components through the ringer, As is I just have to hope for the best when trying new stuff, or just stick what's been holding tough in the past
  • + 5
 It's just the reason I ride a Norco sight c9.1. The shape an the thickness of each Tube are different for each size. Nice feeling and and incredible bike.
  • + 1
 @ReXTless: Not sure what tires you use, but if you're using Maxxis Highroller IIs, buy more before stocks run out. They're discontinued(info from Maxxis).
  • + 12
 Nothing quite like a 175lb person telling 225lb me just how stiff and tough something is. It's like. No. I'll bring your recommended parts back in pieces and TELL YOU about it.
  • + 3
 @Explodo: Maxxis is dropping all 3.0 tires?
  • + 6
 I totally agree. At 215 lbs and riding hard I was destroying 29 aluminum wheels. They also felt flexy and shitty. I have ridden Nobl carbon wheels for 4.5. years without a single issue . Haven't even needed trueing . I run heavier tires with less air and it feels awesome . A cost savings for sure. For lighter riders a totally different story.
  • + 2
 @michaelasnider: That's what they told me in an email. I can't find it right now for some reason. I emailed Maxxis and asked because someone else on here late last year mentioned that Maxxis was dropping 3.0 tires. It makes sense if you look at it because most frame builders seem to be dropping 3.0 as a possible size and the industry seems to have decided that 2.8 is good enough. Schwalbe has reduced their 3.0 offerings as well according to their website.
  • - 1
 @michaelasnider: Maybe I should clarify that 27.5 x 3.0 is going away. I'm not certain about 29x3.0.
  • + 3
 @Explodo: My understanding was that 29 x 3.0 was for sure going away (except the Chronicle for the "Bikepackers"), I'm surprised to hear that 27.5" versions would also be going away, but maybe so.

I did notice during Specialized's Spring sale they were blowing out Purgatory & Ground Control 27.5 x 3.0 tires for $40, those are the only two 3" in their lineup...2.8" tires were not on sale. Will be interesting to see what they spec the next run of plus Fuse/Stumpjumper with.
  • + 2
 hell yea man!
  • + 6
 @alexsin: lol I had someone mock me on here for using sixc cranks on an XC bike.. Im 6'4 220. Things are a bit different for us big guys.
  • + 4
 @Jonzi: I was riding a certain brand of wheel at 26" that blew my mind for how durable they were, along with relatively inexpensive and light! At 6'4, 215 I stick by a wheel that can take my abuse. I then had to go to their 27.5 version....no comparison. I send the rear wheel out of tru so often now, snapped spokes. I have zero interest in ever riding 29(for more reasons than just wheel flex).
A buddy did speak highly of the Nobl carbon, and he's similar size and rides for fun more than race times(abuses wheels). He is still on 26 though
  • + 5
 @GlassGuy: I agree with your assessment of 26" wheel strength and durability. I also have 29ers and 27.5, riding all on aluminum rims. Carbon is a given for performance road rims, where the tires are smaller and need the stiffer support for the higher tire pressures and external stresses - but that doesn't translate to offroad. I have DT, Race Face, Mavic, Ambrosia, and most recently I've added Spank Vibrocore 350s. I added the Spank wheels because I truly love the bars and how they've reduced vibrational stress, and after a month on the wheels (in 27.5), I think they have the right combo of strength/durability and the added benefit of non-rotational energy absorption. Being a much larger rider than you (I'm American Sized, just like burgers!), you may want to consider these wheels when you're forced to the larger diameter.

Oh, and my opinion on 29ers - they have more mass in the tire/rim, so of course they feel like they roll over stuff easier - it's called centrifugal force. But that same mass takes more energy to start and stop, so the smaller wheels feel more livelier and responsive. To give the 29er the same strength as a 26" the rim will require more material. It's simple applied physics.
  • + 13
 @GlassGuy: I think a common arc for riders is:
1) start riding a lot
2) buy lighter components until you get failures
3) go back to components that don't fail
4) basically use those components forever
  • + 1
 Correct. Not one size, stiffness, fits all heights and weights. I'm like to see more options available and it's good see new companies like Forbidden Bike Co, come up with variable proportionate chainstay lengths for example.
  • + 3
 @Geochemistry: If I had my way I'd still be riding 26...I prefer a"lively/snappy/playful" bike, so 27.5 is where I'm staying as long as I can.
My most recent bike came with Ethirteen carbon wheels. I've already put the rear out of tru and all spokes have similar tension, so I'm not sure how long this wheel is going to last me(too damn expensive!) I was looking at the Spank wheels as an option, though if I recall they're quite heavy
  • + 3
 @Explodo: That's about it! I'm still bummed on the changed durability of the wheels I loved going from 26 to 27.5 though. Gotta find an option B
  • + 2
 @GlassGuy: FWIW, I'm 6'4" 265lbs. Pulled the trigger on a set of 27.5 Light Bicycle 35mm Enduro rims shod with Maxxis 2.6 DHF & DHR tires. I was very skeptical but must say that I am very impressed witht their performance and ablity to hold up to my abuse. I'm certainly no pro level rider, but I do ride aggressively on less than manicured trails.
  • + 4
 @GlassGuy: Spank 350 Vibrocore wheels are about 2000 grams with tape and valve's so the weight isn't that much higher than Carbon, and you get a better ride quality in my opinion.
  • + 0
 @GlassGuy: They are heavy, but just call it "roll over" like the marketing guys. Wink
  • + 1
 @GlassGuy: You can still get these 26". They can be run on a 27.5 frame as the radius difference is 12.5mm (diameter 559mm vs 584mm) spank-ind.com/products/spoon-32-wheelset
  • + 1
 If that’s true, I don’t think can’t creek got the message when designing the helm! I had to run low and high compression wide open and with 20+ psi less than recommended for my weight to get it to function at all and it still beat the shit out of me.. had the same problem riding a 36 and now just use lyrik cause it seems to suit me better. @Explodo:
  • + 1
 @Explodo: I just try to find the strongest/most durable components and then bite the bullet and pay extra to get the lightest possible version. It hurts the wallet a bit but i think it’s a good compromise to feel ultimately confident in your gear
  • + 1
 @GlassGuy: i have carbon. 235lbs.
  • + 1
 @twonsarelli: try a mrp ribbon coil.

Also think about rebleeding your damper with lighter oil.
Having the right oil weight will open up the option of actually using the external adjustments that came on your fork.
  • + 1
 @reverend27: thanks for the input but I actually sold the fork and am just running pikes and lyriks on everything, which seem to treat me well. A buddy did just get a coil conversion for his lyrik and if he raves about it I’m considering doing the same.
  • + 1
 @Geochemistry: The problem with getting the "smaller" wheels on a 27.5 designed frame is the BB drop. I'm sure it may work OK on some, but when I got my first Transition Scout I had to go from 175 cranks to 170, as well bumped up the fork from 140 travel to 150 to avoid the massive increase in pedal strikes at my known trails. So I'm sure if I dropped the wheel size I'd be back in the same place again. I like the Scout so much I just got another one
  • + 1
 @GlassGuy: It's a half-inch lower. if you're running bigger tires than the 2" that are design spec standards, you've negated the diameter difference. See the change from 29 to 27.5+ as a comparison.
  • + 19
 Of my own experience of owning 2 different sets of carbon hoops (pair of Enve M70's and later a pair of cheap Chinese copies) my conclusion is that I didn't like them overall.
They noticeably increased arm pump and overall fatigue.
That's been my experience anyway.
Just using standard alu rims with 32 spokes now and happier
  • + 19
 This! Except, I’m the opposite. I’m a bigger guy (6’ 235#), and I really appreciate the stiffer overall ride. Alloy 29” felt sloppy in turns and didn’t track across off-camber. M70HV’s instantly brought back precision I lost moving up from 27.5. I have had less issues with carbon than alloy in terms of durability.
  • + 1
 @nuttypoolog: Agreed.

At 165lbs I find most carbon rims too harsh (long rough dscents) on my 27.5 bike. However I prefer the carbon rims on my 29er. I like the extra stiffness cornering and the reduced weight with the larger carbon rim. The carbon 29er rims seem less harsh also. Giant Reign 27.5 vs. Trance 29
  • + 20
 "I didn't want to change my tires, tire pressure, or suspension."
Yea, I wouldn't start there either, I'd also definitely jump to changing my wheels out.
  • + 16
 MotoGP went through this ages ago. The new Crank Brothers carbon wheels are, according to their designers, done around exactly this notion of appropriate compliance. Same for the Unno carbon frames from Cesar Rojo.

One thing is changing the marketing tune from stiffer = better. That conversation is already starting to happen and articles like this are good step. A completely different challenge is changing the production methods for the vast majority of carbon mtb goods. Composites design for appropriate stiffness involves a lot of prototyping as the FEA methods just don't seem to be there yet. Asian carbon production is going to struggle from "making it so it doesn't break" to making it with appropriate compliance, it is a whole order of magnitude more complicated and demands much more precision. I really only see this happening if production comes back to Europe and North America at a much larger scale than today. And I don't see that happening because people are already screaming about how much bikes cost.
So, expect big budget marketing departments to continue to spew stiffer = better for the foreseeable future while smaller niche players offer up more interesting alternatives at smaller niche prices.
  • + 6
 If those big bugets would be invested in production or engineering instead of marketing BS, we just might get better bikes at lower prices.
  • + 1
 @Ttimer:
It's insane how much money goes to marketing and the people who create this BS.
Lot's of time and money wasted just to come up with the most utterly BS that even a chimp at the zoo could do better.
But that's everywhere, not just the bike industry.
The company I work for wasted half a year and god knows how much money to come up with a 2 word marketing catchphrase that is just so dump.
They shold have asked me.
I could have done the same in 5 minutes for a nice big Döner LOL
  • + 4
 @Ttimer: marketing BS is actually cheap, that’s why it’s so common, advertising is expensive but you would still need to advertise your wonderful engineering otherwise nobody would know about it.
  • + 1
 I've found that cheap light bicycle and other catalog carbon rims are a great balance between stiffness and compliance. They probably hit it by accident, but at 195 pounds I don't have any extra arm pump or fatigue over my old alloy rims.
  • + 8
 @OneTrustMan: but look at the products that are successful:
Fox has relatively extensive marketing and in my opinion overpriced products (certainly in Europe). Manitou and X-Fusion have excellent performance and value for money.
Which brand sells better and which approach is rewarded by customers by buying their products?

The same goes for other components and bikes themselves. Unfortunately, consumers don't always (as in almost never) behave in a way that is beneficial to them in the long run.
  • + 1
 @Mac1987:
Of course it works, or else they woluldn't do it.
  • + 3
 @OneTrustMan: So if it works, then why did you call it a waste of time and money earlier? If it increases the company's profits then it's not a waste, is it? It's actually what puts food on the table of all the other departments.

@Ttimer No, you wouldn't get better/cheaper bikes if marketing/sales/advertising money was put into engineering. Instead, you would get lots of closed down, bankrupt companies, engineers looking for other jobs and less competition with a few big brands dictating the prices/quality (i.e. more expensive/worse). YT or Canyon would never have happened and I'm sure you realise their investment primarily in sales and marketing played a big part in why we can now buy good, affordable bikes - not just from them but also other brands thanks to a change in the market.

The best product will disappear and be forgotten if you can't sell it. @Mac1987 's Manitou/Fox example is a good one.
  • + 0
 @bananowy: With regards to YT and Canyon your argument is incorrect. I actually bought a Canyon back in the day when they wern't a huge international company with boatloads of marketing. Back then they sold good bikes with amazing spec at fairly low prices. Now they sell good bikes with average spec at premium prices.
If you want a good bike at a low price today you need to buy at companies with less media presence, like Radon or Rose.

And your hypothesis about marketing and competition is simply wrong. Marketing goes hand in hand with market power and markets with low levels of advertising/influencing/BS/sponsoring/publicity tend to be less concentrated.
  • + 9
 I'm new to carbon wheels but there are so many options to smooth out your ride. Just switching to a softer tire, a lower psi, or some suspension adjustments should make the chatter smooth out. I definitely wouldn't just swap out my new wheels.
I bet with a good set of wt Maxxis tires you would have plenty of traction.
Am I wrong? What am I missing here? It sounds like we are talking about a road bike not FS MTB.
  • + 2
 You should already be running the lowest PSI you can without excessive compromise of performance or safety. Dropping the PSI to the point where you start dinging rims is just asking for an expensive walk home on carbon rims. That's one of the reasons for all these tire inserts. They give you rim protection to make up for not running a large enough volume tire to give you the compliance you are seeking. Inserts add a lot of weight at the worst possible place to add weight to a bike. I'd rather add 10 lbs to the frame than 1 lb to the tires, but then I like riding up AND down hill.
  • + 1
 I'm new to carbon wheels this season too. Coming from a sloppy set of aluminum e13's, these thing are going to take some serious fine tuning. I don't even know what my suspension is doing at this point.
  • + 1
 In the article I think trying different tires and small psi changes should be considered. I would bet most people would notice changing tires before they would notice rims.
  • + 1
 @Explodo: I didn't say let all the air out.
I have a fat bike too so psi changes are important depending on conditions.
  • + 2
 @Explodo: The inserts I run weigh 90 grams (3.175 ounces) for a 29" wheel. I can't say I notice the weight at all.
  • + 9
 So this is why I've come to the realization I need to swap wheels, not frames.

These days, I pretty much only ride one bike, it's a modern, long, slack trail/enduro/AM/whatever bike that I can pedal all day, or take to the bike park.

I have two wheelsets for it, one lightweight carbon, shod in some trail weight tires, that really makes a huge difference for those 4+ hour pedal fests. I know I can't push them that hard, but the riding I do when I'm in pedal mode doesn't generally involve off-camber rock chutes, so not a big deal.

When it's time to hit the bike park or some trails that have the color black in their rating, I throw on the aluminum rims running DH tires and cushcore. Quite a bit heavier, no where near as efficient, but way more traction and way more durable.

I think you'd hit the nail on the head- but I would recommend instead of having two bikes, just have two wheelsets. Modern long travel trail/enduro bikes are so capable at doing multitasking that I am genuinely questioning whether most riders need more than just that bike (and yes, two years ago I would have called myself an idiot for that statement, but now I'm not so sure).
  • + 1
 I bet if you put the cushcore and DH tires on the carbon wheels you would still be happy. But just switching wheels is easier.
  • + 2
 I know a lot of guys who tried the one for all approach. They all went down in riding ability and were back on a 2 bike quiver (trail and dh) after 2 years.
At least if we're talking dh vs enduro bikes, there is no replacement for a proper big bike when hitting the park or race tracks. Yes you can ride them on a enduro, but your confidence levels are way lower (for most people) and they will inevitably start doging out on some sections, go slower and start making excuses because of the bike they're on. I've seen it happen a lot.
The thing is you just don't notice it yourself,especially when in a group who all do the same.
I also own a dh and a 170mm enduro with proper aggressive geo. There's still no comparison between the two in terms of the confidence they inspire on a proper track.
It's not an economically valid investment of course and from a financial standpoint the one bike quiver is totally fine, but there are definitely points to be made for more than one bike.
  • + 2
 @Loki87: I feel better on my enduro rig at bike parks than my dh rig. The trails are generally pretty buff and the enduro bikes feel way better in the air imo. Prevost style shuttle DH singletrack however, different story.
  • + 1
 @gnarnaimo:
Well, i always assume proper tracks are a given when people talk about how capable modern enduro bikes are.
If we´re talking buff trails, you´re totally right, an enduro can be great for these. However, there´s not really a point to comparing bikes on these as a hardtail will be even better/faster in many cases. I´m totally with you though, ride whatever feels best to you. That said, i never felt overgunned with my dh bike on flow trails. You just get away with more stupid stuff, like sending it to flat.
When people talk about a bikes capabilities, i have to assume we´re talking tracks that actually warrant aggressive geo and suspension and actually pushing the bike to its (or the riders) limits on such trails. For those, even though enduros are quite capable, nothing beats a dedicated dh bike imho. Then again most people are quite happy with just making it down the mountain in one piece. So if all you´re looking for is something that gets you down, they´re totally fine. In the end it probably just comes down to personal expectations. I just dislike the blank statement that enduros are just as capable as downhill bikes, which is definitely not the case.
  • + 8
 “You must be shapeless, formless, like water. When you pour water in a cup, it becomes the cup. When you pour water in a bottle, it becomes the bottle. When you pour water in a teapot, it becomes the teapot. Water can drip and it can crash. Become like water my friend.”

Bruce Lee

Not sure how that will translate to wheels though Razz
  • + 7
 You can rent carbon wheels at some of my local shops, sort of a try before you buy deal. That could help solve the problem for the average consumer.
  • + 5
 Yep, that trend stiffer = better is over long time ago. If you look at rally cars, mx bikes, rc cars. everyone was trying to get it as stiff as possible to some point. At "that" point they realized, that some flex is goog for traction. and now, after few year even MTB industry realized that flex is good. i already knew that :-)
  • + 5
 Well I think its pretty obvious that the lighter weight and higher stiffness of the carbon wheels will make less of a stable ride on a downhill course..... that's why most the downhill riders use aluminum. Its when you need to start pedaling that the carbon really shows its potential vs aluminum so it all comes down to the terrain you ride
  • + 0
 That's not why they use aluminum- it may be a side effect. The why is that damage to the rim tends to be rideable on aluminum and catastrophic on CF.
  • + 2
 @ICKYBOD: I didn't think they cared about finishing the race if they know they already lost. Pretty much most impacts hard enough to make a downhill carbon rim explode would more then likely ding an aluminum rim enough to lose air. If carbon rims were faster they would ride them even if the failure is more catastrophic, these are downhill riders competing for milliseconds... I could be wrong but its what makes sense to me, aluminum rims just go faster because they have some give so when you plow through a rock garden it will be smoother and less jarring, these are the milliseconds the riders are looking for
  • + 2
 @dinsum: as an example, Stan's Flow's were pretty famous for being able to have serious dings and flat spots and still hold air and can often be bent back to shape. CF rims will tend to split out right at the bead seat and the air loss is sudden and complete.

That's what I've been told at least. I'm a hack though myself.
  • + 5
 a couple years ago i read an article (i think it was framed in the same carbon/alloy conversation) where the author outlined the amount that wheels actually flex. if i am remembering correctly, the author determined that any wheel, whether it was carbon or alloy, flexes so little compared the amount of sidewall flex from the tire and the travel of the suspension, that the difference between allow and carbon would basically be imperceptible to the rider, especially given how much tire pressures can be adjusted.

i've seen repeated articles and opinion pieces where other authors maintain that they can feel the difference based just on rim material. perhaps i am not as sensitive as others, but I've ridden all sorts of wheels in all three wheels sizes, both alloy and carbon, and never felt that the ride quality was all that different. it seems that a small change in air pressure would result in far greater deflection of the tire sidewall than any modern wheel would ever flex. that being said, my enve carbon dh bars feel different than the raceface sixc bars and definitely different than the atlas ally bars i used before... but of course you're more directly connected to the bars than the wheels.

what do you reckon?
  • + 1
 I feel that the difference in rotational weight is more noticeable to me than any perceived stiffness or lack thereof in my experience. Lost 2 lbs off of my last wheelset switching to carbon wheels (LB 35mm). On the matter of Aluminum vs. Carbon, I completely agree with the stiffness of the tires sidewalls, along with tire pressures, creating more of a sensation of flex.

I have ridden Enves before however, and rolled a tire right off the rim in a hard corner. Stiffness of the rim vs. improper pressure from my weight? Possibly.
  • + 1
 I wonder this as well. A properly tensioned wheel can't be moving nearly as much as the tire and linkage driven FS bikes. There is just too many moving parts and soft tires to imagine that the wheel of all things would be the thing people would feel.
  • + 4
 As lighter ride I have had to experiment quite a bit to find the right combination of parts to maximize comfort and reduce feedback. There’s definitely more than a few companies turning out frames that are overly stiff. Scott bikes have always been know to be overly harsh and chattery. The same can be said for bars and wheels. Switching out bars and grips can have a big impact on how much feed back makes it to the rider. I have found that most 35mm bars are too stiff and beat up my hands. I’ve switched back to 31.8 bars and won’t be going back to 35mm. Grips make a big difference as well. Changing out bars and grips is significantly cheaper than swapping wheels as well.
  • + 4
 I was about to post the same thing! I found cheap (heavy, thick-wall) 35mm bars almost unrideably uncomfortable. More expensive 31.8mm feel so much better.
  • + 1
 What material are you running? I noticed the opposite when going from Pivot team carbon 31.8 up to 35, it has a softer feel which I like - but nothing compares to the Thomson Ti bar (which is a tad too flexy for me on suspension bikes).
  • + 1
 @pr-g: these were aluminium bars on demo bikes - basic Race Face or something. The bike I bought has slightly more expensive nukeproof bars, still aluminium.
  • + 1
 oh yea. I can see how you’ve come to your conclusion then, I think you’re totally right - pretty certain the 35mil ‘standard’ is pushed for benefitting carbons properties - not aluminium.
  • + 4
 Too many factors to draw any conclusions with this. Rims are not all created equally, some carbon is more compliant than other carbon, spoke butting has a hand in overall compliance, and spoke tension has a huge effect on it as well. Also there are different kinds of stiffness, for lack of a better term. A carbon wheel may have less deflection, but (depending on the rim) it may dampen the vibrations more due to the properties of the material. Similar to Steel Vs Aluminum. Most people think that aluminum is "Stiffer" than steel, but in reality steel is a stiffer material (IE it flexes less) but it does not translate the frequency of vibrations as harshly, so it feels more muted, and more "compliant"

Sorry I ranted a little bit.
  • + 1
 These were my first thoughts too as soon as I saw they were comparing an XM1501 to an XMC1200. The XMC1200 is a trail wheel at best, in its first generation it was defined by DT Swiss as not being able to leave the ground by more than 60cm. The XM1501 is a fantastic enduro wheelset I would glady have again. Compared to the E13 TRSr's I'm on right now the XMC1200s were godawful, horribly stiff vertically and still laterally flexy. Despite both being 'carbon' they are entirely different wheels, the TRSr's are smooth as butter and so I've noticed they allow me to ride faster through rough terrain. This is an interesting experiment but needs more samples to reach a meaningful conclusion.
  • + 4
 Nice article - I think the same general conclusion could probably translate to 31.8 V 35mm bars or carbon / aluminium bars though of course there seems to be more diversity in how a bar feels due to its design / layup and also the stem the bars are used with - a 'system' as you say.

Probably not something the average rider will be able to test much in detail though as you say, having a few spare wheels and a box of handlebars and stems might get expensive.....

Its interesting to see how much thought / testing they put into this subject in Moto GP too, continuously manipulating design and material choice to achieve the required stiffness in areas such as fork crowns and swingarms etc.
  • + 4
 I've done this - was on 35mm bars on one bike 31.8 on the other, switched the 35 to 31.8 with a tad more backsweep and a the wrist tingling was gone! so, in my own experience (yes just mine) the switch was worth it and the 35s just too stiff. (bars are all Alu; ridden 100s of hours on each type)
  • + 2
 @BonoVox101: A lot of the early 35mm standard bars were too stiff. It was as if the designers had forgotten that the main point of a carbon fibre bar was the vibration dampening characteristics. Possibly they were concerned that building the bar too light would lead to failures especially after a crash. Also there is something fundamentally incompatible between the human wrist and a 8º back sweep. 9º to 12º feels more natural.
  • + 3
 I absolutely love carbon wheels.. I live in an area that’s both rocky and tight. The quick acceleration of carbon does it for me.. while I do admit, carbon wheels can ping you off rocks in the chunky sections, it also helps with accelerating up over techy sections. I’ve never cracked one, but I’ve had a few friends crack them when hitting a rock at Just the right angle. Speed / weight had nothing to do with it either.
  • + 1
 Agreed. I weigh less than 150 pounds and still broke my first ever carbon rim when I was running a 2.35 tire on a 29mm internal rim at about 23 psi (which is low but nearly as low as a lot of people) because I was riding fast and hit a tiny but very sharp rock.

The wheelset was manufactured and built by a small boutique wheel brand and they hooked me up with a replacement for basically the cost of shipping and labor. I just monitor my tire pressure more closely and haven’t had a problem since and now run carbon wheels on all my bikes- one set of enves, some ibises and some specialized and none of them have been anything but perfect from day one.
  • + 3
 I honestly haven't even looked at this article or any of the details of what is said. I have tried going back and forth between Stans Flow and a Carbon rims for about a year. I don't notice a thing except my tiny penis feels about 2mm larger when I look at the cool carbon rims. Rim width matters more than material and tire pressure matters more than rims. My opinion.
  • + 3
 I have a 2019 S-Works Stumpy. I sold my carbon traverse SLs and now run 32 spoke Spank Oozy 350. The difference in ride is crazy. The bike is way smoother. The new wheels are heavier but I really don't notice the weight but I am also a 220lb rider. Great article.
  • + 2
 I have the spike 350 vibrocores and they have been amazing so far...
  • + 2
 I recall an interview between Steve Jones and Rob "Box" Cooksley on the matter, maybe even from ten years ago. I think Rob already mentioned back then that for most riders, the added stiffness of the carbon rims isn't ideal. It requires more rider strength for them to track well and and it will wear you out faster.

That said, more than a few carbon rim manufacturers claim that their rims are actually designed to be more compliant and we're getting inserts that go (almost) directly against the tire wall that are also supposed to provide damping. Mr. Wolf and Tannus come to mind. Not saying I've ridden any of these (nor have I ridden a carbon rim) but in this time it may be an interesting experiment. To see if an insert with damping could actually tame a carbon wheel and make it useful for whom a regular tubeless wheel with a carbon rim would be too harsh.

dirtmountainbike.com/features/carbon-mtb-wheels-do-you-need-them.html
  • + 9
 Dirt also weighed DH bikes of pros. They turned out around 36lbs. People still seek ways to drop the weight of DH bikes under 32lbs an whenever a trail bike comes over 32, they go rabble rabble. The only thing we learn from history is that nobody ever learns from history
  • + 7
 But why look towards heavy inserts to make up for the shortcomings of (not-light) carbon wheels if you can just run an alu rim instead?

Obv. this is a simplification, but adding complexity to make up for problems that can be solved by reducing complexity seems like a losing proposition.

@WAKIdesigns 1. How do you know that racers wouldn't be on lighter bikes if they could get the same performance? 2. Not everyone is a racer, some are in it for other types of fun, especially on a trailbike. That tends to be forgotten among all the Enduro-Bro, "slay the trails", STRAVA chest-thumping.
  • + 5
 @Ttimer: A reasonably specced trail bike will normally be around 30-32lbs. The main weight cut to look for is the tyres and in the climate of geometries getting longer and slacker, the geo starts writing cheques 1ply tyres cannot cash. I got my down country bike to 25lbs once and it was barely rideable in my terrain with paperwall tyres, light air sprung fork and shock, no dropper and seat supporting Europan Board of Invasive Proctology. It got back to rideable levels at 28lbs.
  • + 0
 @Ttimer: Could you clarify the "complexity" bit? I went straight from regular tires with (latex) tubes to Schwalbe ProCore. I never tried "regular tubeless" but from what I understand of this "not so complex" setup is that it requires a compressor, straps, tire boosters and whatnot just to install a tire. Maybe not always but considering these products are out there there must be a decent part of the population looking for an easier way to install and seal tires. I can install tires with regular tubes with my bare hands and a mini-pump and the same goes for ProCore. There is no leaking of air before it seals. The tire seats and seals instantly when I inflate the tube before I inflate the tire. I expect the same with Tannus and Mr. Wolf (especially as Tannus still works with a tube). So I've never been tempted to even try regular tubeless. For me installation of those seems complex. I get your point that if the mere reason for a carbon rim would be the weight saving, adding weight of an insert does away with that advantage.

So my suggestion was more of an open minded one. If you can make a carbon wheel less harsh using inserts, would you still experience any advantage over an aluminium rim with an insert? We can argue about it but I thought just because they probably have that kind of stuff ready at the office, why not have an open mind and test it instead?

I'm not using the insert (ProCore in my case) just for compliance (to be able to run less pressure in the tire) but also to protect my rim when doing so. Even though I run aluminium rims (Syntace W35 currently) I still like to protect them even if it weights a little more.
  • + 4
 @vinay: My point is that we should not need to use inserts just to make carbon rims feel less harsh if we can achieve the same ride quality by just using an alloy rim without inserts. In this sense, i consider the use of an additional part to go with the carbon rim to be more complex than just using alloy.

There are of course many other reasons for using inserts.

My experience with standard tubeless is that it is dead-simple to set up with just a floor pump and a spray bottle of water. I can hardly imagine Procore to be even more simple.
  • + 3
 @WAKIdesigns: Are you suggesting that we just toss away mountain bikings deep history and heritage of road bike technology????
  • - 1
 @Ttimer: It seems that there are more benefits to an insert than just making up for "not-light" wheels. Lower pressures without much tire squirm has it's own benefits as well as potential run flat.
  • + 1
 I remember even before carbon rims were a thing (in mtb) that frame designers had realized that too much stiffness wasn't great. I think it was Cannondale that had made that a central part of their marketing spiel at one of their bike launches, that they had "tuned" the amount of flex in the swingarm. Weagle also made a point about going through many iterations of the swingarm of the Wilson to get the flex just right when they first released it. In the recent Vital Inside Line podcast, Rennie mentioned going through the whole flex thing as they developed the V10. Hell, I remember Vouilloz used to run the spokes on his wheels as loose as possible to maximise compliance and grip. (of course his wheels only lasted one run, and no one in the real world can afford that, but still.)

I had all that in mind as I watched the arrival of carbon rims, and smiled as I saw the marketing talk about introducing compliance in the rim. To me, carbon rims, low spoke counts, wider hub spacing, were all just solutions in search of a problem (cough*wagon wheels*cough).

I have a buddy on a Pivot 429 who bought some Enve rims. He hates the way the bike feels, and finds he gets bounced around and knocked about on rough downhills. He wants to sell the bike and get something with 140mm travel. I keep telling him to just get aluminum rims, but he thinks it would be a "step back". to which I roll my eyes. I just sent him this article, so thanks for that!
  • + 0
 @hamncheez: I guess all we need to do is toss away the misinterpretation of road bike tech. Road bike rims are relatively wide with respect to their tire width. To cram a wide mountainbike tire onto that same rim width is taking things out of context. Same with stem length. Road bike bars come back a good bit (backsweep if you will) but putting a flat bar onto that same long stem isn't a good idea. And there are probably more examples. Commuter bikes on the road here (The Netherlands) do have wider tires than road race bikes and they also used to have significantly wider tires than what mountainbikes used to have.

@Ttimer: Yeah again I didn't mean to say it is bound to be a success, just meant to say that if the carbon rims you have feel harsh then why not try to solve that using inserts while you're at it? I personally believe that harshness doesn't necessarily come from stiffness, but from lack of damping. Steel frames aren't designed to be less stiff than aluminium frames, but there is more damping in the material. So yeah my point was, maybe there is something to like about stiff wheels if there is a way to filter out the excess vibrations, like some of these mentioned inserts could. Maybe not. As I said, as they have the stuff over there already, why not try it out? I don't care much about weight. Unless you're starting from a start gate like in 4X racing, I doubt it matters much that it is harder to accelerate. And if you tilt the bike properly when cornering, it definitely won't make it harder to change direction. Unsprung weight? If that is such an issue, then just buck the trend, get a 2X drivetrain instead of a dinner plate and get all your water and tools off the bike and into your backpack.

@slyfink: Yeah, I've got a Cannondale Prophet and indeed the flex in the swingarm was always what the reviewers appreciated when cornering. I also recall that back when RockShox considered moving up to 35mm stanchions one of their concerns was that the fork would be too stiff. It turned out to be fine (or they tweaked it somewhere else) but at least they didn't go all the way up to 40mm or even 38 to match their competitors. I also recall that when Stanton increased their seattube diameter to fit dropper seatposts, they didn't get much love because reviewers felt the character was gone. They tweaked it in their next version. So yeah, too stiff is definitely an issue. It leads to higher frequency vibrations which are considered uncomfortable.
  • + 7
 @vinay: difference in rotational weight carbon vs alu in trailbikes and bigger, is negligible. Standard CF rim for Enduro needs around 450g of stuff to be robist enough to take hits. Robust alu rims weigh 500g. That is why the only place where for Carbon rims make sense is XC and road, because you want to go as low with weight as possible while maintaining stiffness. A 350g carbon rim is stiff and has basic durability. Alu rim of same weight is soft as hell, especially on a 29er or road bike. Road rims, especially TT rims have high profile for better aerodynamics, if made with such section just from alu, they weigh a ton. Back to gravity rims, since you need lots of material in a carbon rim for it to be robust, you lose compliance, no matter the layup. I rode 400g carbon rims which felt at least as stiff as Mavic EX729 which weighs 700g. Latest DT Swiss E-bike alu rims like HX531 are considered virtually indestructible, they weigh 550g, yet Paul Aston messes up 2 Enves weighing 600g.
  • + 3
 @vinay: Simply put, the pros of each material depending on usage:

XC:
carbon: stiffness at low weight
alu: N/A

Down Country:
carbon: stiffness at comparable weight,
alu: price

Enduro/DH:
aluminium: compliance, robustness, price
carbon: N/A

Overall pros:
Alu: compliance, price
Carbon: no need to true, no need to fix dents.
  • + 2
 @slyfink: Funny, I had a 429, and adding carbon wheels made it track and corner so much better, at least in my perception. Light bicycle 30mm rims.
  • + 1
 @panchosdad: I suppose the terrain you ride, your level of skill and speed you ride at all matter in this case. My buddy is rather quick, and we mostly ride raw, natural terrain (which is to say pretty rough). I honestly think the carbon rims, in his case, are too stiff.
  • + 4
 Hey guys, I did 2 runs with 3 controlled variables. The huge difference could only be down to this one thing that I wanted to prove before I started the test. Science!
  • + 2
 I love this article. Really well thought out and nuanced. On my steel hardtail, switching to carbon worked really well for me. It might also help that Reynolds carbon wheels run 28 spoke counts. I'm not sure how much that affects flex.
  • + 2
 I’ve run Black labels on a Spot Honey badger with a 130 fork and it was amazing - that being said the Reynolds feel better than ENVE but of the carbon wheels I’ve ridden here’s the compliance order from most to least: DT XMC (old 24internal version), Ibis 942, Reynolds Black Label Enduro. The stiffness of Enves I only suppose from hearsay having worked at Pivot and being given that reason as to why we didn’t spec them.
I liked the carbon wheels on the steel hardtail precisely because the steel already has a certain amount of whippiness to it.
  • + 2
 @pr-g: Getting a steel full sus soon. Probably going to have to start saving up for more carbon wheels... Big Grin
  • + 2
 This was very informative, even with the caveat of one rider and one "system". This should help a lot of consumers feel better about not having deep enough pockets for carbon everything. Possible add in: "Custom or after market aluminum wheels are stiffer/better than OE spec..." You don't have to go carbon to notice a difference in ride quality. Take the wheels from your 2 or 3 level build spec vs a hand build aluminum set and test that. HUGE difference. I do it with every bike, no need for carbon.
  • + 2
 Why can't rims (and handlebars too while we're at it) have some kind of flex/deflection ratings? One for vertical and one for torsional. Under X load this rim flexes Y amount. Have you ever listened to people giving qualitative flex ratings for handlebars? It's ridiculous.
  • + 2
 Racing motorcycles have found that a degree of lateral flex in the frame is necessary to maintain traction over rough pavement in the corners when the bump force is not in the same plane as suspension movement. www.cycleworld.com/what-about-different-motorcycle-chassis-materials

I wonder if MTB frames have reached the point where we need a bit of flex lateral flex built in (either to the frame or the wheels) to assist with traction when leaning over. Obviously we're not reaching the same lean angles as in MotoGP but we're also riding on bumpier ground.
  • + 2
 When I first got an Enduro 29er back in spring 2014, it felt like crap coming from 26" wheels. I was really pissed that the 'bike of the year' rode so terribly. I had had a 29er hardtail for a few years at that point, and it rode fine for what it was and its intended purpose, but the Enduro 29er rode like crap. I could never get the PSI of the tires right- either too hard and no grip or too soft and the sidewalls would fold over, etc. I just felt like coming from 26" for aggressive riding (I sold my DH and enduro 26" bikes to buy the 29er) there was no precision, control, or proper trail feedback from the wheels. I had more OTB in that spring than the past several seasons combined.

Well, I dumped the cheap stock wheels and put some Chinese cheap carbon hoops on, and it was night and day better performance. I realized that the aluminum rims, at 29 inches, flexed sideways a ton (a properly tensioned wheel will only flex vertically like half a millimeter, look it up) which probably contributed to the sidewall flex in turns. They also had to be trued almost every other ride. I have yet to need to true a carbon rim, and I've been through several sets from several cheap Chinese brands. The OG Enduro 29 still had its issues, but man it was so much better with carbon rims. I felt no extra arm pump or a decrease in traction.
  • + 2
 Horse for courses. I got some carbon LB EN728 rims as they have great reviews and are not that expensive, I opted 28 spoke as a few people I know who work with carbon said that was the way to go as the rims simply don’t need the spokes to hold them true. I’ve put them on two different bikes and swapped them back and fore with DT Swiss Ex471’s. On the hardtail they are too harsh, super noticeable how much smoother the ex471’s are. On the 170mm Enduro bike they make the whole bike feel sharper but in a good way, made it feel more precise.
  • + 2
 Great article. My main reason for running carbon is the super low maintenance, with such a stiff hoop spokes aren’t given as much opportunity to detension. 2,000 miles on my Ibis 942s last year with a very minor touch of one front spoke and 3 rear. I’m riding a Ripley LS that see’s about 80% what it’s made for and 20% of our terrible Texas huck to flats and XC-race-paced rock crawling. Along with around 750 miles split between Idaho and park city last year.

That being said, working at a shop in central Texas with lots of chattery cheese-grater limestone around (on the trails rated for MOARFUNN) I always highly recommend the DT XM481 rim when folks are looking to lace up something sweet. We do a lot of Flow’s too.
But you can’t complain about carbon with the warranties that are currently available.
  • + 2
 I think this means that, every bike review that Pinkbike does, the reviewer needs to ride it with and without carbon wheels and report on the (subjective) difference. A "standard" carbon alternative and a "standard" alu alternative should be chosen first. And yes, the "standard" will change depending on the style of bike being reviewed.
  • + 2
 Rant incoming...

You say this but contradict yourself in the same paragraph:

You say:
"...but I was struggling for traction. On off-cambers and hardpack terrain the bike was skittish and I found it hard to hold a line."

then

"I didn't want to play too much with fork setup or tire pressures and casings as I had found a setup that worked for me"

Maybe those are the things you need to change to counteract the stiffness of the carbon wheels? Maybe you are running tires that aren't suited for carbon wheels, maybe your pressure in the rear tire is too high, maybe you need to dial in your suspension to be more supple for carbon wheels?

Saying you found a problem with traction, but then saying you don't want to change your suspension, tires, and tire pressure because those are perfect? They don't seem to be perfect since you are saying you are having traction issues. You seem to be ignoring the obvious, because you think you have your setup correct, when in actuality, these are the things you should be changing.

Then you go on to say this:
"This test has lead me to believe that we should be looking at our bikes as systems, not collections of components."

You are correct on this, but you are ignoring your own advice, and changing just a component, instead of setting up your bike system correctly for the sum of the components to make it a system. You say you aren't getting traction, and you only want to change your wheels. Wheels do help with traction, but what helps with traction more than wheels is a bike system that is setup correctly for your collection of components. By ignoring the things you don't want to change because you say that setup "works" (which obviously it doesn't, since you are losing traction), you are ignoring your own advice and treating your bike as a collection of components compared to the bike as a system.

This is like going to the doctor telling him you can't walk, and the doctor says, well you have a broken leg, and then you tell the doctor to ignore what's obvious, the broken leg, and that you believe your problem is your hip, and not your leg, as you say your leg is fine and you don't want him to touch your leg. So hey replace your hip at your request, and you see some improvement, but your actual problem still exists, just because you think everything else is ok, when it's not.

Sadly you contradict yourself and ignore your own advice all in one article.

//end rant
  • + 2
 Insightful piece Matt. I like to keep 2 wheelsets for every bike I own, esp. one carbon and one alloy for my main ride. But the
other piece of the puzzle I think may be testing carbon vs. alloy bars,
like Spank’s Vibrocore, to see how The System feels and performs.
  • + 2
 Changing your handlebar grips can make a big difference in comfort and fatigue. What works great on a suspended bike can be painful on a rigid adventure bike. So yes, bikes are systems where all the parts need to work together as a whole for the best results. Good article, Matt.
  • + 2
 A good article that shines a light on something that most people don’t think about or will tackle. That said, as a person who has spent many many years as a suspension engineer and racer of all sorts of things two wheeled (Superbikes, MotoX, Motard, etc), I cringe a little bit when reading the conclusions. But I get why they are what they are. Mainly money and time. In a perfect world the issue of traction and comfort would be handled by tuning frame flex, suspension setup tire construction/trad design/pressure. Not adding “bendy” wheels to the equation. Chassis (frame) design/flex is a massive factor in all things two wheels. More so as the grip levels go up. Same with tires. There is a massive amount of tuning going on there. Way back when I was racing Superbike my Ducati frames had “bars” that could be added/subtracted for tuning purposes. I used them often to tune for different tracks. Currently most of the top teams in on and off road racing have multiple frames with different “tunes” in them. They are swapped out to suit track/trail conditions. You will even find that two riders on the same team running the same pace using two different frames. So, personal feel and preference is also a factor. I think in the case of this exercise it would be prudent to do something more comprehensive that included a professional tuning the suspension and multiple tires/pressures. Would the results be the same? Possibly. Could the same times be achieved with both sets of wheels with suspension tuning? Possibly. Could the carbon rims come out on top with some suspension tuning? Possibly. What about tires/pressure? It’s a huge factor. In a perfect world you would have unlimited time and an unlimited budget to test for the best solution. The best solution would be to achieve the best times on the carbon rims because they’re lighter and will transfer power better. How much work would need to be done to achieve that? Can that be achieved? Unknown.
  • + 4
 aluminum all day. carbon is $$$ and non recyclable. save the world bikers ! c'mon
  • + 1
 Carbon actually is reusable. They add it to road asphalt.
  • + 2
 www.facebook.com/StarlingCycles/videos/1380399148727271

Great little video about compliance and cornering grip. Subject is steel frames, but same idea as this article.
  • + 1
 Starling's look so good. If I had the money, I'd buy a full sus. If I had a bit more money, I'd definitely buy a starling.
  • + 1
 I just switched back to aluminum wheels. My bike rolls much smoother now and my hands don't get so fatigued any more either. Selling the used carbon wheels covered the cost of a sweet aluminum, custom built wheelset! Could not be happier.
  • + 1
 Great article, more of this please!
It reminds me about a story a hardcore 50y/o + windsurfer dude told me.
Company's in the surfing industry started pushing the tech way to much and it kind of ruined the sport in some way (in the surfer his eyes). Just regular people were surfing on pro boards + huge sails and were not having a good time anymore. They were professionalizing the tech way to much and it took a lot of the fun factor out.
  • + 1
 After trying out a top end carbon fibre super bike recently i came to the conclusion that carbon fibre is massively over rated, and I mean massively!!. The bike cost well over double that of my metal bike and only rode maybe 2% better. I could understand this obsession with carbon If the bike rode incredible but it just didnt. Not by a long way. If id have spent all that money i would have been devastated. Stick to metal. Its cheaper, rides just as good if not better and will last longer. This obsession with carbon needs to stop.

Bring on the neg props, the more the better!!
  • + 1
 Nice article. One thing I often see is though: stiffness is not strength. I DO want the strongest bike possible so it doesn't break, but not necessarily the stiffest as explained very well above. Using normal materials and techniques these two can/do correlate, but you could have an extremely stiff bike that still cracks and Fails under minor loads.
  • + 1
 Great article but such a complex issue as @mattwrag suggests, made even more complex by riding style and terrain. I build my own wheels so I can play with variables such as spoke count and tension to play with ride characteristics. Bike set up still is huge though as evidenced by the ridiculously stiff set ups some the pro's put on their suspension, but then others have a much compliant ride. Not to mention whether trail surface make up (#Ihavenoloam) and whether it is wet make a difference. Certainly a well built set of aluminum rims is not holding anyone back, and well built carbon rims are beautiful and reliable.
  • + 4
 Come on Pinkbike you gotta tag this stuff NSFW. You know we're reading the site at work.
  • + 3
 Yeah I can imagine your colleagues might look at you in a funny way when they read "My personal stiffness" on your computer
  • + 1
 @zede: To be honest, that whole section left me pretty flacid.
  • + 1
 29er ALU+ALU Carbon 35mm bars !ERGON GD1! never been more comfortable.....But I think it´s mostly because I am getting more and more picky with tire and shock/fork pressures. By best tip is to get a digital pressure gauge if you don´t have one. But those GD1 grips are super...
  • + 1
 alluminium rims cost $100 not one thousand. Alluminium rims don't feel wooden. alluminium rims are just as light or almost. alluminium are stronger. alluminium rims come in different colors. I don't get the reason for buying carbon rims.
  • + 1
 My unsolicited yet indisputably essential opinion is that starting from the "middle" of the bike (system) the importance of stiffness decreases in an inverse proportion to the distance from the (imaginary) middle (when speaking of frames). I ride a hardtail and had a carbon rim on the back and could not get anything close to a good "systemic" fluidity regardless of how low my tire pressures got. I realize few people ride hardtails, but my point is this: if one wishes to spend money on stiffness, the frame is where to do it. I love a wide, stiff alloy rim because I can run it into things and not worry about breaking it. I am convinced that until some magicry makes carbon rims self-repairing and free, carbon rims are not worth it. Carbon frames (especially full suspension) are worth it.
  • + 1
 You seem to be in-line with the conclusion of the author of the article. But what you're convinced about for wheels is likely to be for your own use case rather than a general conclusion. (You probably realize this.) My case brings me to a different conclusion.

I notice a bit more non-compliance than I'd like in my carbon wheels on carbon frame when descending, and I also have a moderate need to pick my lines reasonably well rather than blast through rock gardens. I'm fast, but not point-and-shoot fast. I acknowledge that some people find the latter the high point of their riding experience.

But it's a tradeoff I'm happy to make for my situation, which includes massive climbing every ride. I enjoy climbing a lot, and I enjoy it much more with my highly-responsive carbon wheels, where I make fun little mini-sprints out of the climbing turns that I believe contribute power training to my other sports.

So for my use case of all-mountain round trips, I'm convinced that light carbon wheels are best.
  • + 1
 Stiffness/ride quality is one of the reasons I lean towards 27.5 vs 29. I know I can build a solid, responsive 27.5 wheel with an alloy rim that will hold up, not be too heavy, and have a nice balance of smoothness and support. For my riding, when I go 29 I prefer a carbon rim to maintain a similar level of dynamic response. Alloy 29 rims just feel vague, unless they're burly in which case they're quite heavy. 27.5 wheel platform allows me to build a lighter, more affordable bike that still performs at a very high level. Just my 2cents
  • + 1
 i know this problem, i used to ride a Foes RS7 which is a pretty stiff frame & rear triangle with Mavic DeeMax Ultimate, then i switched to carbon rims and my bike was unrideable, even on easy blue trails, it was way too stiff, so i switched back and all was good again.
I´m riding the carbon rims on my Turner DHR now and they work perfect on that setup.
  • + 1
 This the second PB article that has definitively claimed that aluminum is "compliant". It's also not a "theory" in reference to Matt Wragg's 'more compliant (aluminum EVO) frame,' it is simply his opinion. Readers should definitely take these opinions with a grain of salt.
  • + 1
 As I have dumped my 27.5 stuff and switched to exclusively 29, I’ve really come to appreciate carbon wheels and the stiffness.

When I had bird arms I couldn’t handle the stiffness but now that I’ve bumped to 15 lb dumbbells I can hammer thru stuff and really take advantage of the stiffness.

Basically get swoll and carbon is better. Otherwise just cruise around and it doesn’t matter.
  • + 1
 I'm building a new set of wheels and would like ya'lls input.

Is the CB Synthesis philosophy of a compliant wheel up front and a very stiff wheel in the rear, a sound one?

Or should a CF wheel build focus on compliance front AND rear? Is more better, or not really in all cases?

Thanks for your input.
  • + 1
 Seems sensible to me. You have twice as much weight on the rear wheel so it should be stiffer.
  • + 1
 The real problem is that suspensions suck. If you have to rely on uncontrolled wheel flex, you have a poorly designed suspension system. Half of the adjusters on a modern fork are useless, Rockshox as much as admitted that in the info about their new stuff. To be fair, they're a bit stuck as most people want to buy the cool guy suspension for catching huge air, when in reality 3 feet is more than they'll ever get. Thus, suspensions are way overdamped for most people. It's like everyone wants a supercross bike when they really need a soft trail bike. So lets compensate by building soft wheels?
  • + 1
 nice article, i'm in the same boat kind of im racing xcm this season and my xc carbon hardtail is already as stiff as it gets now should i make the whole system even stiffer with carbon wheels just to shave of 200 or 300gr or be tkae aluminium wheels to maek it just a touch more compliant over 4+h of racing
  • + 1
 Please do the same test on your evo! Just bought a set of we are one agents on pro4 hubs. Have to get rid of those soft rovals. What really draws me to the carbon is the lifetime warranty and in my experience with we are one they are significantly more durable than alu wheels. I'll have to test the traction theory out for myself though
  • + 1
 I've found that the long chainstays on the evo make the back wheel feel more flexy, so he might like carbon rims on that bike.
  • + 1
 Simple truths

1. If you ride hard and fast you 100% will break your carbon rims eventually.

2. Your buddies will keep riding and you will be side lined until your fantastic warranty rims are returned.

3. If you love riding you those grams you saved with carbon aren’t so sweet because those days you sit trackside feel like weeks.
  • + 1
 I have been running carbon only rims on my FS bikes for past 5 years and Alu only on steel hardtail. My next wheelset for FS once carbon dies (they all eventually crack) is going to be Alu for sure. Although carbon wheels a little snappier and maybe stiffer on lateral loads, they are likely not worth the premium upcharge over Alu, unless XC racer and want the lightest possible set up. My DH lay up carbon rims weigh almost as much as same width Alu rims. Over past 1.5 years, have cracked three carbon rims regardless of lay-up and one set of Alu rims with small hop on one wheel with over 2 years of hard use on the hardtail. So, for me carbon is just not worth it. Haven’t had a crack on carbon with foam liners this past year yet, but still not worth the hassle and expense I think.
  • + 1
 I'm a heavy, decently strong rider, but don't charge psycho hard and don't have a tendency to break shit. I really like stiff-ass carbon everything, including wheels. The first time I took a tight local hairpin on a carbon frame in 2014, it was a revelation. Never noticed how much my frame had been moving under me until it wasn't. A few years later, carbon wheels were less of a game changer, but I still feel the improved (to me) ride quality and really appreciate it.

That said, while the people i know who race CX, road, and XC don't break carbon wheels, the ones who race enduro and downhill do. They trash alloy rims too, but it's less expensive. Those wheel breakers also do appreciate the stiffness of the carbon rims when they're in one piece.
  • + 1
 @mattwragg
Hey Matt nice article. I went through exactly same process (same carbon rims Ibis 741) when moving from my 2015 Devinci Spartan to 2018 Pivot Firebird. The Pivot has a very stiff frame, so when paired to carbon rims it gave an akward feeling that translated in early fatigue and less control of the bike in certain situations. I agree that one must look at bikes as a whole and that it also depends on personal preference. What one can conclude though is that a same wheelset will NOT perform the same on different bikes. Simple as that.
  • + 1
 I can't help but think that if they left out superboost on the Switchblade and Firebird etc. that the bikes would still ride really well and get the benefits of those awesome wheels without being overly stiff.
  • + 2
 What about running an aluminum rim up front and a carbon rim in the back? That'd achieve the same thing as the new CB wheels announced yesterday, with supposedly a supple front and rigid rear. Right?
  • + 1
 I didn’t read all the comments so I’m sure it’s been raised already; all things being equal an alu frame is actually less “compliant” than a carbon frame.

A well designed carbon frame is not just aimed at reducing weight but to achieve specific compliance effects.
  • + 1
 The head line was click bait. The story is on how the parts you choose to build up your bike make up a system that has a specific tune. And judging by the first 20 comments went over most people's heads. Interesting write up.
  • + 2
 carbon wheels are cool for larger riders or very aggressive riders with lots of expendable cash. for everyone else aluminum work perfectly.
  • + 2
 Good write up. Anyone poopooing this needs to go see what works best for them. I'd personally rather ride a square Al rim than a carbon hoop.
  • + 2
 Good read. A similar conundrum exists with the 35mm vs 31.8mm handlebar diameter. Some flex in the right place is a good thing.
  • + 1
 Best watched at .25 speed starting at 1:22 (Fabio Wibmer). Smile

youtu.be/RlgDlyMmUaw?t=82

I went from LB 38mm carbon to DT XM481 alum, LB carbon feels responsive but imo it's too stiff, I prefer the DTs.
  • + 2
 Changing rims because you refuse to adjust tire pressure to accommodate trail conditions. Rolleyes

We've officially reached peak pinkbike.
  • + 2
 Until the brittleness of carbon und the very slight difference in weight vs. aluminum is worked around, I'll be sticking with metal.
  • + 2
 When I was young I liked'em as stiff as possible, now that I'm older and little softness in the back brings some welcome comfort.
  • + 1
 rec'd for Freudian slip...
  • + 0
 Intradesting, very intradesting. As someone who still remembers riding with bent handle bars, and breaking frames in half, I don't know. Then there comes the wizardry that is carbon fiber, which has been fucking laughable compared to the very jaunty claims they used to make about it. I would recommend steering clear of anything man made at the end of the day.
  • + 12
 so a bike then
  • + 1
 Anything man made? Uh....

You are aware that aluminum does not naturally occur in it's pure form, or even any useable alloys, right? It has to be refined out of bauxite ore, then further mixed into the desired alloy, then precipitation hardened (usually), then machined/welded, and heat treated again.

The manufacturing chain for carbon fiber is more labor and capital intensive, but it also involves fewer steps.
  • + 3
 So just get a sustainably harvested aluminum frame from the forest.
  • + 2
 Don’t ever buy wheels from DIY Carbon Bikes. They will fall apart and then the customer service will let you down! Really disappointed, back to Aluminum...
  • + 1
 Good article! Enjoyed it a lot because I can relate. Went through countless wheel sets over the years trying to find the right weight ratio and stiffness. After trying Carbon I can never go back to aluminum !!!!
  • + 2
 I'm currently rocking the mullet setup. An aluminum rear wheel and carbon front wheel. Party in the rear and business up front.
  • + 1
 Closely mirrors my experience with the Spartan and the PB review with it. Reviewed bike ran carbon wheels and bar / it’s amazing how much difference a Praxis alloy rim and vibrovore bar makes to the entire package.
  • + 4
 A "brief" history of "stiffness." I see what you did there.
  • + 0
 Its like surfing- a lightly glassed PU or eps has an indescribable springiness/soul to it- similar to steel frame. I never understood why mountain bikers want the most plush suspension (which handles forces in limited dimensions) yet the absolute stiffest frame.
  • + 3
 Great article! Described everything I was noticing and experiencing with carbon wheels. I stick to aluminum.
  • + 1
 Those original Stans Crest 29er wheels were like having 2" extra travel on the bike. They flexed a ton, but I actually didn't mind it. Especially on a hardtail.
  • + 3
 How about trying aluminium on the front and carbon on the rear?
  • + 1
 Thanks for the interesting article. I’ve just upgraded wheels on my alloy 2019 Spesh Epic Evo. Rather than going carbon I chose Praxis AL32 on i9 hubs. So glad I did
  • + 1
 This is a nice article that hints. Please, stay away from the specific brand that everyone keeps cracking wheels over and over again.
  • + 2
 One thing I do know is that wheels indeed perform better when there are better tires on them Razz
  • + 1
 we need more of this , I sometimes thought my current bike was just a little too stiff and thought carbon wheels would put it past what I liked , good stuff
  • + 2
 No one complains about aluminum wheels not having a lifetime warranty... think about it, why is that
  • + 0
 I've spent a lot of money trying to improve speed for racing. In the end I've gone with a carbon rear for acceleration and less weight slamming against rocks and an aluminum front for wrist, arm and upper body endurance.
  • + 1
 I wonder how much spoke tension plays a role in this. In other words, were the wheels tested right out of the box, or where they hand built and tuned to the author's weight?
  • + 2
 too stiff?


that's what she said
  • + 1
 Nicolas Vouilloz was playing with spoke tension and compliance in the 90's.
  • + 2
 I will use carbon wheels if I have so much money.
  • - 1
 Just get I-9 system wheels with aluminum rims if you want stiff wheels. Their 32 spoke chassis with an alloy hoop is just as stiff or stiffer than most carbon stuff build on j-bends.
  • + 0
 Good wheels they are but stiff compared to carbon or a j-bend DT Swiss rim, they are not.
  • + 2
 Just go I9 aluminum save yourself some cash.
  • + 2
 I....am....an....adult........must.....resist...jokes....
  • + 2
 Nice wheels are nice wheels - regardless or material.
  • + 1
 I saw stiffer was better so i wrote to viagra got a sponsor and now i have stiff rims and yes they are alu lol
  • + 1
 decent read with critical thinking and still the article comes out low on the nerd spectum
  • + 1
 As long as DT Swiss makes the 471 & 511 there is no need for anything else.
  • + 1
 Carbon in back, metal in front. I wish companies would sell these as a wheelset package.
  • + 1
 The carbon tide is going out...……..
  • + 1
 Is no one one going to raise tire sidewall/pressure here?
  • + 1
 More content like this, seriously!
  • + 1
 well, what about ZIPP 3Zero Moto?
  • + 1
 Fat and wide carbon in the front a little skinnier aluminum in the rear
  • + 1
 Choices are good, that's what it comes down to.
  • + 2
 So is 26 dead yet?
  • + 1
 Annnnd this is why SuperBoost hubs is stupid for the majority of riders.
  • + 2
 That's what she asked
  • + 1
 But did you have more fun on one or the other?
  • + 1
 Also, bravo on the article. Well done.
  • + 1
 This article is a total joke.
  • + 1
 great article! that is all.
  • + 1
 Great work there, Mr. Wragg. I like the 'holistic' approach to things.
  • + 2
 Ask yer mom
  • + 1
 More of this. Thank you.
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