The Wrong Tool For The Job

Well, we've had this year's warped rim incident.  It happened in a century ride, on a hill that the rider described as "incredible.  Long, steep, and windy..."  The rider is a big guy (240 pounds), making his situation a perfect storm of the sort that I described here last year.   The disappointing thing about this is that the rider who had this happened got in touch a few weeks ago to tell us that he loved the wheels, but had popped a tube on a descent and wondered if the 145psi he regularly used was too much pressure.  We reiterated that we recommend no higher than 125psi, that 145 was dangerous, and that we did not recommend carbon clinchers for situations where one might need to control one's speed for long distances. Exactly the kind of situation he was in. 

A lot of companies out there will tell you that carbon clinchers are a great choice in any situation.  It's our firm belief that this has never been the case and that it is not now the case.  Carbon clincher manufacture has improved, as has brake pad compatibility.  Some situations that would have demolished first generation carbon clinchers are well within the envelope now.  As a testament to the strength of our carbon clinchers, consider that the rider who warped his rims had already exploded two tubes on this ride, without damaging the rims.  This is in addition to the tube he'd exploded prior.  So his tubes gave him two very loud (I presume quite literally) and clear warnings, yet he pressed on through.  

The concerning thing for us in not that we now have to make with a new set of rims and build a warranty set.  Yes, we are going to warranty this set, although the absolute disregard for what we thought were pretty customer-centric use and warranty terms and conditions have caused us to modify them (new T&Cs here).  The concerning thing is that by using such the wrong tool for the job, the rider and all of the riders around him are put at serious risk.  

Carbon clinchers are a fantastic tool for a lot of riding.  I am I don't know how many thousand miles into my set, and they have been flawless, and they are currently the only wheels I have to use.  That is the kind of faith we have in our carbon clinchers - they are the only wheels I currently use.  I'm also 165 pounds, don't ride down monster switchback descents in traffic, don't ride my brakes, maintain my brake pads, and generally stay within the use parameters we've always espoused.  Although we really don't recommend it (and have always excluded damage from it), I raced our district's annual "spring classic" - complete with one mile of dirt road per lap, for a total of six miles of dirt road taken at race speed - on RFSC38s last weekend. And I wasn't dicking around at the back of the field either, I made the break and got fifth.  Last night, I took several trips down a hill that's about 1k long, straight and steep, using several different braking techniques.  Normally, you'd get to about 35 on this hill before needing to brake for the light at the bottom.  I held my speed to 20 on one descent, and though the rims were warm to the touch, there was no issue. 

Heat warping does not happen in normal use modes.  It happens when you take the wheels out of the parameters in which they work.  There are few better wheels to use in your typical road race or office park crit than a well built set of carbon clinchers.  As evidenced by prominent rides (notably, Levi's Gran Fondo) preventing their use, there are some situations in which carbon clinchers are the WRONG choice.  Going down what would ordinarily be a fast and challenging descent with 500 or 5000 of your closest friends, some of whol might be a heck of a lot more proficient at going up hills than they are going down them, is the wrong time to be on carbon clinchers. 

Despite quite a bit of marketing to the contrary, this isn't an issue that the expensive brands have solved.  A bit of Google will show you that, and I'll tell you once again that almost exactly one year ago I saw, firsthand, a set of the most heavily marketed carbon clinchers fail due to heat - in exactly the type of conditions where we warn of their deficiency. The specific set of wheels that are more than any other responsible for the decision taken at Levi's Gran Fondo cost well in excess of $2,000.  You can't hide from physics, no matter how big your marketing budget. 

We like our customers, and want them to enjoy cycling and be safe and have stuff that performs well.  It doesn't take a lot of customer education to convince people that, for example, a mountain bike race is the wrong place to use your road bike.  Unfortunately, it takes quite a bit more effort to convince people that carbon clinchers are not a wheelset for every condition - even direct and specific warnings emailed personally go unheeded.  That being the case, we feel it necessary to take a couple of actions.  First, the terms and conditions have been updated.  Second, we will no longer be selling carbon clinchers in spoke counts higher than 20/24.  The world's most powerful sprinters don't need higher spoke counts than that (although they do all seem to prefer 24 spoke wheels), so wheel stiffness is not a concern.  This move is purely to discourage those riders who are bigger than would be adequately served by 20/24 spoke counts to choose wheels other than carbon clinchers.  We will lose sales because of this, we know that.  There are cases in which riders might wind up with the exact same rims we sell, but with higher spoke counts.  We simply feel that this is the reasonable and responsible course of action for us and our customers.  

See you at the office park!

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Oh hey look, a troll. Sounds like someone is sore over paying for a marketing budget.Appreciate the candor and engagement from you guys. Also, loving the FSW 23s with WI's. I haven't touched my 58s since I got them.


Excellent article, thank you for posting. Good reminder that for all the good attributes of carbon clinchers, there are drawbacks as well.


Wow no SOB builds that sucks.My 150 lbs and my buddies 200lbs will miss them.Jere B

Jere B

Your warranty disclaimer states, "These warranties cover only defects in materials and workmanship…No claims of fitness of use are expressed or implied." I'm surprised you didn't just say that this guy's damage constitutes consumer misuse and please refer to the crash replacement policy. He might complain, but too bad. The Internet is full of people complaining because a bike or bike component company didn't warranty something after it exploded whether or not it appears to have been due to a legit defect or user error. People still complain even if it does get warranty replacement: Do some Googling about older generation Zipp 303s cracking. If you have now added the new exclusion in the Terms for damage caused by riders over 200lbs, why eliminate a wheel build that would be optimal for such riders in some circumstances?


SYJ – A few reasons why we're disinclined to do them:1. They're heavy. The people who need them most are unlikely to want them – "light for the climbs."2. Ebay is littered with Cosmic Carbones and the like. I realize that new is different than used, but they are all over the place built and in good shape for short money. Chris – Spoke count has no effect on heat buildup. We know that there is "usage seep" with our wheels (people sneak usage outside of the box that we recommend). But we've made wheels that perform really well within the recommended box for guys who weigh 240 (the guy who spanked his rims LOVED the way they performed when he used them as recommended) – usage seep for a guy that big can have disastrous consequences. A 190 or 200 pound guy is going to find our 20/24 lacing in a 58mm wheel to be more than adequate for the job – we know this to be empirically true – and the outcome of his usage creep will be less dangerous. We have found through testing, research and observation that the point of diminishing returns for a wheel feeling "torque stiff" (resistant to huge power input) is right around 24 spokes in the wheel depths we use (it's actually lower in 85s). We've found we need to make our wheels less attractive to the very big rider. We had been one of a very very very few players with a solution for that (perhaps the only one). We knew we would disappoint people with this move. We have to accept that.

Dave Kirkpatrick

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