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Editorial

Why Would Anyone Buy Carbon Wheels?

Words Cam McRae
Photos Dave Smith (unless noted)
Date Jul 12, 2017

I should start this by coming clean; I have a carbon fetish. I'm powerless to the pull of carbon frames, bars, cranks and brake levers. Even stem caps. Rims are a tougher sell to many but despite their exorbitant cost and several other issues (some related below) carbon rims make sense to me. The 6th element on the periodic table that is common to all known life, seems like the right material for the job. The stuff makes graphite, diamond and graphene (the strongest material known) and it's plentiful, so how can it not be the right stuff? 


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I was so enamoured by the lateral stiffness of the first Enve rims I rode (back in 2010) that I failed to notice the lack of vertical compliance. Precision is intoxicating. More recent models have a better feel for the trail.

There were some seizures and growing pains in the early history of carbon hoops, including exploding sidewalls, melting rims, bone shaking stiffness and bait and switch lifetime warranties but lately, it seems things are starting to settle. Quality, performance, and consistency have all been on the rise. The two factors we'd like to see spiraling downwards, weight and price, have sadly remained relatively constant.

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Because they look sweet? That's answer enough for some riders. Mavic's XA Pro Carbon rims under testing load with no air pressure.

Part of this infatuation relates to my experience. Thus far the wheels I have ridden have been very good. I've had one compressor-related failure while encouraging a tire to seat on an ENVE rim (huge explosion with sealant everywhere) but otherwise the performance and reliability have been excellent. Carbon is particularly good at staying true and round because unlike aluminum, carbon structures have no memory; rims don't strain to keep a circular shape because they have been laid up as circles from the beginning. Aluminum rims begin as long straight extrusions that are bent into a circular shape, often four at a time. If you have ever potato-chipped a rim you have experienced a rim trying to claw back to its unbent form. The counterpoint is that usually, you can smash an aluminum rim back into rideable shape. Even one that looks like a Pringle. 

Jesse Melamed Madeira

Jesse leading at the EWS Madeira before a carbon rim failure pushed back his first overall victory. Photo - Enduro World Series

Jesse Melamed discovered the limitations of carbon rims earlier this year when a failure cost him an overall win in Madeira. Jeff Bryson, Team Rocky Mtn Urge mechanic for Jesse and Remi Gauvin tells the story: 


We started the season on carbon rims this year only because they (Jesse and Remi) had ridden the same wheelsets the prior year and had no issues all season. When Jesse's rim blew up on the 7th stage of EWS Madeira with a 24 second lead, all the EWS mechanics (Polar Bear - Team Yeti, Mark M - Factory GT and Mateo - Jerome Clementz) reminded me "that's what carbon does." We are now on Aluminum with Cushcore. Aluminum shows its abuse and is cheaper to rebuild. Most of the mechanics make their riders ride aluminum. Rear for sure - Jeff Bryson

Of course at the EWS level most riders and mechanics aren't paying a penny for their parts, and aluminum rims can be replaced frequently so there is no issue dealing with the usual afflictions of dents, flat spots and wobble that plague aluminum rims in abusive relationships. Jeff's point that aluminum doesn't conceal issues is particularly important for racers at the top level. The one team that has had no issues with carbon rims is Specialized because they apparently start with fresh ones ever race.

Team Specialized relies on carbon wheels but they apparently swap them before every race.

Team Specialized relies on carbon wheels but they apparently swap them before every race. Photo - Enduro World Series

So the jury is still deliberating about carbo loading for this application. For riders who put less monumental demands on their wheels, the advantages of carbon are more easily identified. You have to have strong opinions if you are going to pour your life savings into building wheels out of carbon so I asked Dustin Adams, once Canada's top downhiller and now the proprietor of We Are One Composites, a Kamloops based startup making carbon rims here in Canada, what he felt the advantages of carbon hoops are:


The main advantage is an increase in wheel Stiffness for the same or lower weight compared to an aluminum rim. With the main advantage being the increased lateral stiffness for better tracking, improved steering feel, better cornering. The Radial stiffness is also increased, but we have engineered our rim profile and layup to minimize this increase, so it doesn't have a harsh to ride feel. - Dustin Adams, We Are One Composites

I posed the same question to Nic McCrae, the carbon engineer behind Santa Cruz's recently released Reserve Wheels. 


Carbon rims won't deform unless they break, which keeps your wheels dished and true way better than an alloy rim. Also, the extra stiffness makes for a more predictable and precise ride. And especially with wide rims, it keeps the wheel light. They're expensive, can't lie about that, but a properly made carbon rim will last forever, is as close as feasible to a maintenance-free wheel, and give you a lot of bang for the buck. - Nic McCrae, Santa Cruz Bikes

It's an expensive day when you hit something too hard or too sharp with your fine carbonium hoops. e*thirteen's rims on their own range from US$499-$549 while a similar aluminum version is $79. Carbon frames are certainly more expensive than aluminum but not almost 7 times more expensive, so putting some thought into your buying decision is essential. But what makes carbon rims so pricy? Again Nic McCrae had some info for me:


Two main factors here: raw material cost and because they are hand-made. Carbon prepreg's cost is in the tens of dollars per pound, while aluminum is the single digit $/lb. It takes over an hour to lay-up a rim in the layup tool, even using the semi-automated equipment SCB developed, and then it needs over an hour in a heat press, demolding, deflashing, drilling, finishing, etc. Many many man-hours per carbon rim, opposed to minutes to form and weld an aluminum rim. Nic McCrae, Santa Cruz Bikes

There are some pros and cons. No shocker here. A few more factors are that tubeless works better with the hookless bead of carbon rims (fewer burps) and the accuracy of the structure means you are more likely to get a good seal from the beginning. Because carbon doesn't sustain dents or flat spots the seal is again going to have better integrity. 

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I've been impressed with the Mavic XA Pro Carbon wheels I've been testing lately. But you hope to be impressed for US$1800 a pair. 

So they are light and strong and low maintenance. The bad news is that when they do fail, as they did for Jesse, it's often catastrophic. The short history of carbon rims reminds me of the first round of compact florescent bulbs. Dumb consumers like me were told they would last 20,000 hours and so we paid a premium. Unfortunately that was bullshit. I had a dozen that didn't last a year because of course they hadn't actually tested them for the predicted lifespan; that answer was pulled directly out the marketing departments asses. 

When Easton launched their Haven Carbon wheel program they came with a sweet lifetime no questions asked warranty. Unfortunately that warranty was cancelled when RaceFace purchased Easton. No amount of testing is going to prepare rims for every real world situation and the only way to know with certainty how a product will perform for consumers is to have thousands of riders push them to the limit. 

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The Norco Range Carbon I tested recently came with (gasp!) aluminum rims! I had no issues with performance or durability for the duration of the test.

Should you buy carbon-rimmed wheels? If you are on a tight budget the answer is no for me. If you are fussy about your wheels being round and true learn to build wheels. It's not that hard and lacing is easy if you re-use spokes (just tape the new rim to the old one and transfer the spokes over one at a time). You are going to spend between $1000 and $2500 for your wheels to start off with in American dollars. You can get a really nice aluminum wheelset for $500 and replace the rims several times before getting anywhere near the price of a carbon set. 

Another reason to avoid carbon is ever-changing standards. Anybody who threw down for an expensive set of non-Boost 650b wheels is unlikely to look back fondly on that purchase. And it's even worse for anyone who picked up a 26" set. 

If you happen to be someone who is content to throw money at mountain bike gear then I highly recommend getting down with some hand laid rims. Many riders find them virtually maintenance free because they resist any deformation until they reach the breaking point. The regular truing required of aluminum wheels rarely needs to be performed in my experience. Another positive is the compliance built into recently released carbon rims. Lately I have ridden Mavic's XA Pro Carbon, e*thirteen's TRSr SL and Santa Cruz's Reserve wheels and they share excellent lateral rigidity (no newsflash here) but they also provide impressive compliance leading to improved comfort and grip. 

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Cushcore even protects your rims when your tire loses all its air. Riding out is a comfortable calming affair. 

A proviso in all this for me is that I am vastly more comfortable on wheels that retail for over 3k Canadian with Cushcore inserts between my carbon and the earth's bony bits. If it was only the peace of mind protection provides that would be one thing but the performance advantages of Cushcore make it automatic for me. 

Cushcore on rim

Protecting your carbon (or aluminum) holdings while boosting performance? Cushcore has delivered for me thus far. 

I'd like to be able to tell you that my tea leaves indicate standards are going to settle down and that carbon rims currently being produced are going to outperform the previous generation by several parsecs (a country mile isn't enough). Anecdotally at least I have a degree of confidence about the latter statement but I wouldn't bet much on standards levelling out, so think carefully before blowing a pay check on wheels for your bicycle. 

Comments

Lowcard
+1
Lowcard  - July 12, 2017, 7:18 a.m.

Let's be clear: there are shitty carbon rims and there are good carbon rims. I wouldn't just generalize about them because the build (layup) process can be so different from brand to brand or model to model. Slight changes in layup or fiber orientation can make a massive difference in strength and feel. For some high production overseas carbon brands, they rely on fast efficient production with less concern about engineering in the optimal layup.

In aluminum, its akin to comparing a Rhyno Lite to a DT Swiss 471 rim. Not the same playing field.

Carbon rims can be engineered to be both radially compliant while remaining laterally stiff. Its all in the layup.

Reply

alexdi
0
Alex D  - July 12, 2017, 10:06 a.m.

> Carbon rims can be engineered to be both radially compliant while remaining laterally stiff.

Explain?

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cam@nsmb.com
+2
Cam McRae  - July 12, 2017, 10:21 a.m.

Think of a metal ruler like you might have had  when you were a kid. Try to bend it in one direction, so the flat surface is bending, and it flexes easily. If you try to bend it so the narrow edge flexes and you won't have much luck. Not a perfect analogy but there is a similar concept at work.

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alexdi
0
Alex D  - July 12, 2017, 8:29 p.m.

Cam, the radial deflection for any bicycle wheel, carbon or not, is essentially nil because the spokes bear the load, not the rim. The rim makes no significant contribution to vertical compliance until the spokes are slack, which should occur very, very rarely with a well-built, highly-tensioned wheel. From an engineering perspective, the only benefit of a compliant rim is that it won't crack as easily in this scenario. I've yet to see a coherent explanation for perceived ride quality benefits the rest of the time.

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cam@nsmb.com
0
Cam McRae  - July 13, 2017, 10:19 a.m.

Alex D - this is responding to your point below about spokes being responsible for compliance. (might have to adjust how these threads flow!) How do spokes prevent radial deflection on impact? The rim is held in tension rather than compression so deflection can't be prevented by spokes (with a few exceptions like Easton's original Haven Carbons with rims that aren't perforated). In fact the impact vector will be in line with spoke tension rather than opposition. Having ridden carbon rims with similar lacing patterns, spokes and tires but a very different feel, my experience doesn't align with your contention.

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alexdi
0
Alex D  - July 13, 2017, 6:38 p.m.

Cam, that isn't how spokes work. As a wheel is loaded, the spokes on the bottom progressively lose tension. As long as tension exists, the wheel deforms only to the extent the spokes contract, typically on the order of a millimeter. (This has been verified empirically and with FEA.) When the load exceeds the available tension, the excess is distributed to the rim, and to a lesser extent, the other spokes. 

Alloy rims will taco not long after this point if you introduce a lateral force. Carbon rims will either break or flex. Until you've run out of spoke tension (typically on a bad landing or a major hit at speed), however, there should be no perceptible difference between rims with similar lateral stiffness and other relevant (e.g., width) characteristics.

I assume you've experienced an alloy rim with a flat tire. Perhaps even a skinny road-bike alloy with a handful of spokes on a narrow hub. How compliant was that rim? Do you think a carbon rim, equally less a tire, would have been any smoother?

Reply

cam@nsmb.com
0
Cam McRae  - July 13, 2017, 9:21 p.m.

Are you telling me you have never experienced a difference in the feel of a rim Alex D? And what do you mean about spokes contracting? As in reducing in length? And I guess you are calling BS on all the manufacturers who have been trying to engineer compliance into their rims? If we assume a similar wall thickness and construction, would you say that a rim that has a depth of 2" will feel identical to a rim with a depth of .75" assuming similar spokes and lacing pattern? Was the testing you speak of applied to mountain bike rims or road rims?

Reply

alexdi
0
Alex D  - July 15, 2017, 10:55 a.m.

Cam, I have to quote you to make this coherent, sorry.

> Are you telling me you have never experienced a difference in the feel of a rim Alex D? 

The question is whether a difference in vertical compliance exists while the spokes still have tension, not whether there's a general difference in rims. Width, weight, lateral stiffness, the hub, and spoke lacing would all impact an overall impression, not to mention the terrain and the rider's inclinations at that moment. Perception isn't relevant when you can directly measure what you're interested in. 

> And what do you mean about spokes contracting? As in reducing in length? 

Under tension, the spokes stretch to an extent dictated by their thickness, the level of tension, and Young's modulus for steel. When the wheel is loaded, tension reduces on the bottom spokes, so they contract. A wheel with more spokes or thicker spokes will be considerably stiffer (less deflection) vertically, though perhaps only by fractions of a millimeter for most loads.  

> And I guess you are calling BS on all the manufacturers who have been trying to engineer compliance into their rims? 

There is a benefit to vertical compliance, it's just not to the rider. Rims that can flex when the spokes are slack are less likely to break. Fewer warranty claims. You could make a thin safety argument here. I wouldn't expect any difference in ride quality (with exception to a handful of very aggressive riders that do, perhaps, exceed spoke tension with some regularity.)

http://www.noxcomposites.com/wheel_building ;

That's a good summary.  

> If we assume a similar wall thickness and construction, would you say that a rim that has a depth of 2" will feel identical to a rim with a depth of .75" assuming similar spokes and lacing pattern? 

Yes, in a straight line, under loads that don't exceed spoke tension. The 2" wheel would be laterally stiffer. 

> Was the testing you speak of applied to mountain bike rims or road rims?

Both (and of course, the FEA doesn't distinguish). While the Nox article has some nice theoretical numbers, you can find out yourself; pick a wheel without a tire, measure the wheel height carefully, load the top of the rim, and measure again. I'd be surprised if your measuring instrument was accurate enough to detect any difference at all.

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primoz-resman
0
Primož Resman  - July 26, 2017, 9:14 a.m.

Alex D the rim bending inwards is actually caused by it being squishable together (when for example no spokes are used). Yeah, the spokes carry the weight through tension, but they carry it from the top, not from the bottom. Lacing the rim with many spokes gives it a certain stability, but the rim itself will still want to flex inwards, if thin enough (in the vertical dimension).

On the other hand, you can hardly make one diameter of a circle smaller without making the perpendicular diameter larger (making an oval), which means the spokes in other areas of the rim will try to prevent tis deformation...

Reply

cam@nsmb.com
+1
Cam McRae  - July 12, 2017, 10:22 a.m.

Good point. I should have made it clear that I was speaking of quality carbon rims that have undergone testing, using quality materials and construction etc. I guess I thought the examples I was giving would make that clear but I should have been more specific. Thanks for making that more clear.

Reply

xy9ine
+1
Perry Schebel  - July 12, 2017, 11:02 a.m.

love the idea of a more compliant carbon rim. i prefer the feel of aluminum over the (very stiff) carbon rims i've ridden so far.

Reply

Reverend
+1
Tim Ambler  - July 12, 2017, 8:53 a.m.

One nice thing about carbon is that depending on how they break (full explosion vs. a crack) they might actually be repairable. I was experimenting with low pressures on my Ibis 941 wheels and found the cracking point on my rear rim. I was initially crushed by my investment going down the tubes but Roberts Composites was able to repair and I've been riding the same rear for about two years now. Had to pull out some spokes temporarily and get it re-tensioned but it a full rebuild of the wheel wasn't necessary. Try that with aluminum.

Reply

cam@nsmb.com
0
Cam McRae  - July 12, 2017, 10:23 a.m.

Nice one Tim. I have a rim that is waiting for an assessment from Rob. I've seen some great work done by him.

Reply

xy9ine
0
Perry Schebel  - July 12, 2017, 10:59 a.m.

i had a cracked carbon frame repaired by rob - solid work at a reasonable price. the (potential) repairability of carbon is pretty neat.

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primoz-resman
0
Primož Resman  - July 26, 2017, 9:17 a.m.

With the price of carbon rims they better be repairable for life!!

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dtimms
0
dtimms  - July 12, 2017, 1:01 p.m.

One thing that seems odd to me, you buy 3k rims and then have to spend another 100 on inserts so they don't break? Man, I will take my aluminum rims.

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shoreboy
0
Shoreboy  - July 12, 2017, 2:38 p.m.

The Cushcore inserts also add ~250g+ to each of your wheels.

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cam@nsmb.com
0
Cam McRae  - July 12, 2017, 10:49 p.m.

But you can easily save that by running lighter tires. I'm running some light Mavic Quest Pro XL and with Cushcore they perform better than the substantially heavier Minions they replaced, and the trail feel is amazing.

Reply

shoreboy
0
Shoreboy  - July 13, 2017, 10:50 a.m.

Just to play devil's advocate, I could also put CushCore in my aluminum wheels, use the lighter tires, and get the same trail feel.  All at about 1/5th the price.  The weight difference between Al rims and Carbon rims is a dead heat.

Reply

Lowcard
0
Lowcard  - July 12, 2017, 7:05 p.m.

Who does that? Seems like they just don't have enough of the right type of layers in the nipple bed.

woops.... just realized you were talking about foam inserts hahaha

Reply

RussBobrowski
0
RussBobrowski  - July 13, 2017, 10:22 a.m.

What's the weight difference between a set of carbon and aluminum rims suitable for all-mountain use? Stans vs noble or We Are One?

Reply

amrskipro
+2
AndrewR  - July 13, 2017, 4:30 p.m.

@ Perry Schebel: I have had ENVE DH, ENVE M70, Light Bicycle and NOBL wheels/ rims, and I am waiting for my set of We Are One Composite wheels at the moment. I would never go back to Aluminium unless I was given them for free. The design and quality of the carbon is important. I broke a Light Bicycle rim (sudden extreme compression whilst crossing a sharp object seems to be the undoing of carbon rims) and to their credit and email with photos and an explanation had a new rim and complete set of new spokes in the post within a week (which they needed to colour match the rim art work). The ENVE DH are still going after five years including over 400 Whistler Bike Park guiding days (so lots of mistakes, hours and wear and tear) and two different frames. 

The ENVE M70 were too stiff (no lateral or vertical compliance at my riding speeds) and given the relatively strong US/ Canada dollar exchange at the time I sold them to someone who wanted them more than I did. I also disliked the internal nipple thing which requires a complete strip down to replace a broken spoke.

The NOBL TR38 wheels are amazing and I am spoilt by having a spragg clutch rear hub, but about the carbon, Dustin made sure that the profile was such that there was some lateral and vertical compliance built into them. They are way better than the ENVE M70 (less harsh due to the shallower rim profile as well as lay up) they replaced as well as giving my favourite tyres a better tread profile. They have survived two years of hard riding, including a Trans-Provence, with only some cosmetic scratches to show for it. 

For my riding I really should have got the NOBL TR33, which would ride with a little more compliance at my weight and riding speeds, but I really liked the foot print that the TR38 gave the tyres so I went burlier than I should have for my riding style.

To help off set the stiffness of carbon, and take advantage of the strength increase and weight saving, I usually get my wheels built up with Sapim CX-Ray spokes. They have the best strength and fatigue life of any spoke so are worth the extra price in my opinion. 

I am moving to We Are One Composites as I believe in supporting "Made in Canada" and these are hand made in Kamloops, plus I trust Dustin and I have seen how 'badly' they have been treated by some of his "way more talented and faster than me" development riders and they keep coming up shining. The Project 321 hubs are not made in Canada but they are hand made by our southern neighbours (USA) which is better than outsourcing everything to China in my opinion, plus they have the quiet pawl engagement option which I now prefer. 

For the peace of mind of total reliability (rims, spokes and hubs) I don't feel that that a good carbon wheel set is that expensive when one considers that a DT Swiss wheel set will run close to $1000 and one will probably be replacing them annually.

If you are in Whistler you are welcome to give them a try.

Reply

Lowcard
0
Lowcard  - July 13, 2017, 6:45 p.m.

Thanks for the support brother! We truly value the kind words. It is very important to us to have viable manufacturing in Canada. And to think some people said it couldn't be done...... well here is proof it can.

Reply

Endur-Bro
0
Endur-Bro  - July 17, 2017, 5:33 p.m.

I'm planning on getting a set of We Are One Agent rims laced up to a set of ONYX hubs for my future build.  Just waiting on fork availability now before ordering up a hub set.  Unsure if I'll go DT or Sapim spokes though, brass nipples for sure though.

Reply

ReubenSandwich
0
ReubenSandwich  - July 13, 2017, 7:20 p.m.

People often talk about the dropper post being the best upgrade to their bike. Dropper is great.... but when I put Zelvy hoops on my Blur LTc 3 years back it made it so much more lively and playful. I didnt save a heap of weigĥt over the crossmax wheels it replaced but the weight that was saved was rotational and going to King hubs and wider rims also made for greater reliability.  I just traded up to a new Slayer and that will be getting the carbon treatment also. I think it is one of those things that you just need to ride it and see for yourself, the positives far outweigh the negatives.

Reply

primoz-resman
0
Primož Resman  - July 26, 2017, 9:10 a.m.

> If you have ever potato-chipped a rim you have experienced a rim trying to claw back to its unbent form.

Boy is this statement wrong...

Reply

Vikb
0
Vik Banerjee  - Aug. 7, 2017, 6:34 a.m.

My Light Bicycle carbon rims cost twice what the other quality AL rims I run. I've had the two bikes each ridden for 6 months a year over the last 3yrs....one sporting LB carbon rims and one sporting AL rims. Same width, same tires, same trails, same type of 6" bike and same rider. The rear AL rim is dented to shit and needs to be replaced. The carbon rim is still perfect despite more than one pinch flatted tubeless tire on that rim.

Once I replace the AL rim paying for the rim and labour to rebuild the wheel running AL will be more expensive on the rear of that bike. The front AL rim is doing fine.

We've got about 10 sets of LB carbons rims on various bikes of folks I ride with. The oldest are 4-5yrs old and nobody has had a failure to date.

I just built up a new set of LB carbon rims for a new bike and can't see any reason not to keep using carbon. It's strong, it's light and LB rims setup tubeless really well. The cost differential is small between carbon and AL.

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