Carbon Clinchers—Are They Ready for Prime Time?
Last February the guys who promote Levi’s Gran Fondo, Bike Monkey, issued a press release asking riders to leave their carbon clinchers at home. The ride takes in a fair amount of descending and some of the roads riders drop down are simultaneously steep and twisty. It’s not a great combination for riders who may not have a lot of experience and/or confidence on descents. One road in particular, Meyer’s Grade, hits 18 percent, but of course does that in a stretch followed by a slightly off-camber left.
In my personal experience, I’ve gone as fast as 44 in that section. A friend of mine did 54 there.
When Bike Monkey issued the release, I took some note of it, but knowing that their first interest is to prevent injury and give entrants the best, most successful experience possible, I didn’t blame them. For some years I’ve been seeing carbon clinchers fail in the Santa Monica Mountains. The descents that bring riders down to Pacific Coast Highway drop, on average, 2000 feet and contain an either terrific or terrifying mix (depending on your view) of steep drops and frequent turns.
Frequent readers of RKP have heard me sing the praises of these roads in Malibu. They are the most challenging descents I’ve ridden anywhere, including the roads used in Levi’s Gran Fondo.
Epic Fail
I’ve seen a fair number of carbon clincher failures. We’re talking melted brake tracks, flat tires, wives called for rides home. I’ve contemplated a post on whether carbon clinchers were really a product that was as safe and reliable as aluminum clinchers. My concern was that it was unnecessarily argumentative, that I’d be picking a fight where none was required.
Just more than four months have passed since Bike Monkey issued that press release. It seemed that a well-intentioned advisory would go unnoticed by the industry, which was just as well. Then I got this from Reynolds Cycling:
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Huh?
Forgetting for a moment that it took them four months to formulate a response, and that it mostly reads like marketing copy, Paul Lew’s rebuttal to the concern about carbon clinchers attributes the problem to a cluster of riders of varied abilities and that people are just riding their brakes too much.
Well, Paul, thanks for throwing the consumer under the bus.
Here’s a newsflash: The first rule of PR in any product failure is never to blame the consumer. This was a disappointing dismissal of a valid concern. I believe it deserves a response, so I reached out to friends that I ride with plus a couple of retailers to ask them what their experience has been. What I heard back wasn’t surprising given what I’d already seen. Friends and retailers reported failures of the brake track due to braking heat with the following manufacturers: Reynolds. Easton, Enve, Bontrager, Roval and Lightweight. This is but an anecdotal sampling, unscientific even, but it’s significant because the population it draws from are competent riders who are accustomed to the mountain roads above Malibu and earned their skills racing crits here in Southern California. They know how to corner; they know how to brake. I’ve got a family who depend on me, so I can say with some conviction, if these guys were buffoons, I wouldn’t keep riding with them.
In the case of Lightweight, Easton, Enve and Roval, there were very few reported failures. In the case of Roval, they were all first-generation wheels; I heard the second generation has been much better. Bontrager had double the rate of failure reported for the others. Reynolds had more than six times the rate of failure of brands like Lightweight. Now, I need to add a caveat here: Reynolds’ market penetration is superior to those other brands; I don’t believe it would be fair to say that the Eastons are six time as good a wheel as Reynolds, but what is troubling is that nearly everyone I talked to about Reynolds’ carbon clinchers reported that they had killed more than one set. Friends I talked to commended them for their excellent customer service (one friend who killed wheels from Reynolds, Easton and Bontrager said that Reynolds’ customer service was both the quickest and least expensive), so there’s that.
The Upshot
One needn’t be a timid descender to melt a carbon clincher on the canyon roads in Malibu. You don’t need to be following someone else who doesn’t know what they are doing, or riding your brakes because you’re behind a car.
I know this to be true because I melted a Reynolds Stratus rear wheel descending Las Flores road at the absolute limit of my ability. So badly did the brake track deteriorate in one section that I had to pull over and get the bike stopped so that I could open up the brake quick release and then loosen the barrel adjuster so the brake wouldn’t rub the wheel. And I wasn’t even finished with the descent. The steepest portion of the descent was yet to come; I was scared shitless until I reached PCH. Even then, things didn’t improve much as I still had to pedal 20—mostly flat—miles home.
It would be easy to accuse me of riding my brakes down that descent, that I was too timid to let the bike run and that’s why the wheel melted. Well, you can check out my times for descents like Tuna Canyon, Las Flores and Decker on Strava. You’ll see that I’m reasonably fast, fast enough to consider brakes counterproductive to a good time. When that wheel melted, I was not the problem.
The Exceptions
The retailers I spoke to noted that what they aren’t seeing returned are Enve’s new SES rims and Zipp’s Firecrest Carbon Clinchers. While I can’t speak to the new SES carbon clincher (I don’t even know anyone who owns a set), I can say that I’ve taken both the Firecrest 303s and 404s down Las Flores, and though at a certain point the brakes howled like a dog for a full moon, braking remained consistent and the wheels remain perfectly true.
I wouldn’t be responding like this had I not experienced a rather surreal meeting with Paul Lew at Press Camp. Now, I like Paul; we’ve spoken in the past and I think he’s a really cool guy with whom I share full geekage. But in our meeting, when I brought up the issue of carbon fiber clincher failures—broadly, I wasn’t even pointing a finger at Reynolds—he sidestepped the issue and began with a marketing pitch for how their new brake shoe shares a polymer with the resin they use in the brake track that lowers braking temperature by 100 degrees. When he knocked the Firecrest and SES designs and insisted that the RZR was a much faster wheel and I tried to ask about handling issues that Firecrest and SES address, he dodged that as well. After leaving the meeting I told a friend that I felt like I’d been told the sun rises in the west.
People of the bike industry—propaganda is for politics. If you want me to write about your products, you need to be prepared to have a candid conversation with me. If I feel I’m being fed a line of bull, I will be less inclined to call in the future.
I think that the guys at Bike Monkey made the right call. They don’t need me to have their back, nor do I have a vested interest in their success, but in the interest of disclosure, I’ll admit that I know them, like them and appreciate that they provide me with free entry to their events. And yes, I’ve even contributed to their magazine. They are good people who made a judicious call.
Here’s the bottom line for most consumers out there: Generally, carbon clinchers work really well. If you live in a flat or moderately hilly place, they’ll be perfectly fine. I’ll hazard a guess that were I still riding in the Berkshires of Western Massachusetts, I wouldn’t have a problem with them there, either. However, the Santa Monica Mountain provide the most technically demanding descents I’ve encountered. There are spots in Sonoma County that rival them, though. Wheels are failing on these roads. And the wheels that fail on these roads are carbon clinchers exclusively.
Finally, I’m issuing an invitation/challenge to the entire industry: If you make carbon clinchers and you think they are up to any challenge, come ride with me.
I routinely ride on carbon clinchers, I have a pair of Edge 45s and Reynolds 66s, both circa 2009 so before the latest in rim construction from either company. I have not had any problems with them in riding and racing in my region, but most of my terrain is rolling and the longest descents are maybe 3 km. I am a very confident descender and bike handler, raced cat 1 road and elite XC MTB. Grew up riding motorcycles, raced motocross from age 8-19 and basically spent 41 of my 43 years on 2 wheels of some form, yadda, yadda.
Last fall I traveled to Santa Rosa and did Levi’s fondo for the first time. It was a super-fun event and I really enjoyed it. Having read of carbon clincher problems in previous years, I took some well-used Campy Eurus wheels and I was pretty pleased to have done so. First, the roads in Sonoma are ROUGH. Second, when I descended the Hauser Bridge section it was kind of drizzly wet. With the wet, unfamiliar road and a few other cyclists as obstacles, I was definitely on the brakes hard and long. Part of that descent hits 22%. I found that descent to be one of the nastiest I have done on a road bike and I was darn happy to have alloy rims and my trusty KoolStop salmon pads. I am not sure I would have made it down Hauser on my Edge clinchers without a potential issue.
I’ll be back at Levi’s again this year, but I won’t be bringing carbon wheels.
I think one could argue that everyone is right here. Carbon clinchers AND tubulars fail from time to time. Everything fails from time to time. I’ve worked on the retail side of the industry for 15 years and now own a shop. I’ve seen aluminum clinchers fail because the brake track was simply worn thin. Carbon wheels have come a long way in the last 5 years and I feel that they are very safe and reliable. I’ve ridden carbon wheels from both Reynolds and Enve for about 6 years now and have yet to come across a problem. We have had to warranty wheels from EVERY company mentioned in the article. Some due to heat issues, some due to spokes pulling through and so on. When we discuss carbon wheels as an option, we fully disclose all the potential problems. If you are a timid descender (nothing wrong with staying alive by the way) you will likely ride your brakes more, if you do a lot of centuries where you are stuck behind riders who are slower than you, you’ll ride your brakes more. That does cause heat build up. Carbon wheels may not be the best choice. To blame the consumer is partly unfair, the retailer should be concerned with the safety of their clients and they should understand the product they sell, they should also make an effort to understand the client’s needs and it’s on them to make good recommendations. Sadly, the internet doesn’t ask you questions nor does it care about your riding style. This is why you buy from your local shop but that’s a whole other problem. Carbon wheels do perform extremely well and I have to say that for me, personally, I will always ride carbon. I do have a set of traditional hand built aluminum clinchers though for rides that may be inappropriate for carbon.
My Bontrager XXXL Carbon clinchers melted pre-riding Levi’s Gran Fondo. Grew up riding and racing in NorCal and I am a good descender. Brakes failed instantly on a very steep section and then required hard braking just to modulate the speed from being out of control as the pad/rim braking surface was melted and not engaging. Both rims deformed and were ruined. Had to swap out my buddies aluminum wheel just so I had one wheel to brake with and finish the ride. Aluminum only from me for now on for big climbs and descents.
Padraig,
Thank you for this very informative and honest piece on carbon wheel use/technology. Honestly, I have never understood the fascination. I completely understand the aerodynamic etc. benefit of a carbon rim for the person who genuinely benefits from their use (usually at higher speeds). However, when used for climbing (and descending), it seems as though it’s just a bridge too far.
Your descriptions of rim failures under heavy braking loads is enough to convince me that I will probably never own (nor need) a set of carbon rims. BTW, the previous comment about seeing aluminum rims fail as well….they did so due to braking surface wear i.e. after many thousands of miles and not catastrophically. A bike shop could have measured those wheels and predicted those failures. Not so on a carbon wheel.
I recently rode the Seattle to Portland Bike classic (back to back centuries). I was surprised to see some of the participants on carbon wheels…..doing about 17mph. As has been noted, technology is great and very important in our sport, however, every once in a while we come up with something that I think isn’t ready for prime time. Carbon clinchers is one of these.
I hit the asphalt at 60km/h during the first descent of the 2010 L´Etape du Tour in France. I was going down the col de Marie Blanc full-speed when my rear tire blew in a hard braking moment just before a sharp turn and BAM! I was using my ROVAL wheels, 2008 model, I believe the rims are from Reynolds (or so I was told). I finished the event, bleeding but alive, for the rims stayed perfect even after the crash and heat of the hard breaking.
I used the Rovals the week before, and kept using it a week after in those same long, fast Pyreneean and Alpine descents without problem. The thing is, the night before the Etape I found a cut in my tire and thus replaced both. No problem there except the tour guide was prepping the group bikes so he was using the pump and filled my tires up to 130psi without telling me (or me asking him). I usually run 100 front and back in such circumstances, that´s why I never had a problem before or after.
The wheels are perfect still, even after thousand of miles of hard use, racing and training, including some potholes and rocks and even dirt road riding. I use Zipp Carbon and Platinum pads and get decent braking even in the wet, though of course not up to an aluminum hoops.
I confess I´m quite amazed at how much abuse those carbon rims stood. I´m light on equipment but not overly zealous, just carefull and technical. I´m not as confident riding it as I am with my HED Ardennes but then it´s aluminum and wider than the Rovals. But I can´t really say they´re fragile or something.
I live in a place with varied terrain, we don´t have any 30km long infested with U turns but going down some roads here I reach near 100kph and some are really technical as well. I´ve been to the Andes and those are long, fast descents with technical turns and the Rovals have performed, if not up to the point of mu lovely HED Ardennes, at least decently, and they´re still alive to tell.
I´ve seen a friend blow a DT carbon tubular during a hill climb and descent race here and it´s not pretty. To me, I trust a carbon clincher yes but whenever I need 100% confidence in my wheels, as during a hard race or in the rain, I still prefer a good lightweight alu clincher with top tires and tubes.
I am very impressed with this article. It is very difficult for journalists to report negatively on products from potential advertisers but this is an important issue. As someone who trained and raced in the Colorado mountains for over twenty years there are serious concerns about potential equipment failures especially related to the build up of heat. I learned quickly, never train on sew-ups when the route descended on sustained switchbacks beyond about 10% grade because the glue often liquified. Even the temp on aluminum clincher rims can become frighteningly hot on that type terrain. I would put carbon clinchers somewhere in between sewups and aluminum clinchers so unless in a racing situation I feel that risk is an unacceptable trade off for the performance increase. I think this was the point Paul was making. But Paul Lew expressed concerns and considering he has been a leader in composite technology for at least thirty years and has been instrumental in bringing countless innovations to cyclists I would listen to those concerns. If you live in the Mountains discs brakes future looks bright.
I was talking with the Mavic rep in the Mid-Atlantic region a few weeks back, and he said that it has been the judgement of the Mavic engineers, after significant testing of in-house prototypes and competitors wheels, that it is not presently possible to build a carbon clincher that can withstand sustained braking forces. I know someone who had a pair of Bontrager wheels, and had them melt on a descent in the Rockies. Makes sense to me.
Disc brakes… Yes you’re right in thinking your roadies brakes are powerful, but think about the inherent safety of taking all the heat away from the rim, mountain lovers rejoice, now is the time to get seriously carbon excited – as for the weight weenies and inertia calculators, that party is about to get a whole lot more exciting as well!
I read an article that the Cervelo guys gave a presentation at Interbike and they said the same things that the Mavic guys said…Avoid carbon clinchers! Sounds like Zipp are cutting edge in the resin dept. I would stick with HED or Shimano clinchers. Go tubular if you want race wheels.
Padraig replied to Ransom with -
You bring up a really terrific question. Here’s what I’ve been told by the brightest minds I’ve spoken with who have been willing to be candid with me. Hard braking on twisty mountain descents produces big spikes in temperature. They can produce really high temps, but by getting back off the brakes that heat is able to be dissipated through the rim. Sustained braking won’t produce the high temps of hard braking, but without that opportunity to dissipate heat by getting off the brakes means that the temperature just builds and builds. Eventually it’s enough to overcome the curing temperature for the resin and the brake track goes plastic.
(Twistiness has nothing to do with heat except as a cause for braking)
Padraig is correct that hard braking produces big spikes in temperature but the part about dissipation is questionable. When you start your 2000 foot descent you have potential energy thanks to gravity. All those Joules have to be turned into heat in your descent, with a small bit left over for your final kinetic energy at the bottom.
Your descent heats up the air and the brakes. Someone may have the skill to descend Las Flores without touching the brakes but not me. I ride much slower than terminal velocity. What happens when I ride the brakes? The Joules are converted into heat. The rate of heating (Watts) is Joules divided by time.
If I descend at a constant speed my rims have a N-Watt heater applied. If I halve the constant speed my rims have a 1/2 N-Watt heater in operation. The rims will be cooler. Riding the brakes is not harmful, dissipating energy quickly is harmful.
Gravity rules. If the grade of the road doubles and the speed stays the same the heater goes from N Watts to 2N Watts.
Pulsing the brakes will produce spikes in heating – true, but the total energy that must be dissipated will not change. The average over time will be the same (for the same average speed). However the spikes may trigger a heat failure point in the rim. Riding the brakes is not harmful, dissipating energy quickly is harmful.
I just had the chance the ride the new Roval CLX 40 & 60. Very impressed with weight, speed and the testing they did with Overend, a 50 kg backpack and Mt.Washington… AND they are relatively affordable. Mavic might be affraid of the r&d involved but I’m stoked that some companies are seriously getting it together.
Quote “The retailers I spoke to noted that what they aren’t seeing returned are Enve’s new SES rims and Zipp’s Firecrest Carbon Clinchers..”
Quote “Reynolds had more than six times the rate of failure of brands like Lightweight”
Quote “I know this to be true because I melted a Reynolds Stratus rear wheel descending Las Flores road”
Are these implied comparisons really fair? I guess all manufacturers have tried to address this issue with their latest wheels, but you seem to be comparing the latest generation wheels from Zipp and Enve with older Reynolds wheels (well, not exactly, but it could easily be read that way). Any data / feedback on the failure rate of the latest Reynolds wheels with the CTg brake tracks?
Neil: Try to keep in mind that the motivation for this post wasn’t some objective equipment shootout. It was a rebuttal to what I took to be blaming the consumer for wheels that consistently failed in the Santa Monica Mountains. Could I have constructed a more objective sampling? Absolutely. Were those quotes in some way unfair? Not in my view; ultimately reviewing is subjective and anecdotal. I do my best to make my work as objective as possible, but I was limited in the number of riders I could sample, and for the record, I did eliminate results from some riders who admitted they were timid descenders. As to comparing Zipp and Enve to Reynolds’ new work, no one I spoke to was riding the wheels, but I’ve spoken with Reynolds and I should be riding a set soon.
I’ve read this post several times and I really like the way you’ve presented the issue. I was an early adopter (ie before all my friends) to CC’s with the Reynolds Cirrus and Stratus. I melted both pairs while riding in North Carolina. The scared shitless issue is not a small thing that can be marketed away. I then rode a pair of Easton EC90 Aero’s which I loved. They warped in Miami. Apparently they are notorious for failures and it has something to do with production at the facility in Mexico.
To make a long story short, I’ve switched to the new Mavic Ksyrium SLR. They’re just about as light and you really can stop in the rain! Carbon clinchers give up lots of braking performance in the wet and until you squeeze an SLR you won’t believe the difference.
I’m not a fearless descender by any means but you have to ask yourself, do you really want to worry about your wheels on a fast twisty descent? Catastrophic failure is a real possibility and Mr. Lew’s claims to the contrary, I can’t recall an alloy clincher warping.
Hi, i found it interesting in a recent copy of Road Bike Action a report of the Gran Fondo showing both Levi and the author of the article riding S-Works Roubaix’s fitted with Zipp 202 FC clinchers. Seems to be a case of Do as I say and not as I do….