How it happened (described by user) : "Wolf SL (all carbon) on a Cervelo Soloist Carbon. About 8,200 miles on the fork. Installed per instructions with the epoxied aluminum insert at a reputable shop (bought new at my LBS). VERY short (I run no spacers at all). FSA OS 115 stem torqued to spec. 155-165# rider. Stopped at an intersection, heading for some hill riding (Indian hill area of course for the Cincy peeps). Started and torqued the bars some to get a jump through the intersection at the green light - SNAP! Down, right in the middle of the intersection. Just about got ran over by the minivan behind me (tire about 2 inches from my leg). Didn't know what happened."
Long Story Short : Steerer tube on a Cervelo TT bike failed where an aluminum insert ended, at the top of the headset. Cervelo doesn't apparently make these forks, True Temper/ Alpha Q does for the former party. The Al insert didn't extend past the upper headset. There was a difference of opinion between the companies as to the dimensions of the insert, and the math in the installation instructions were messed up. As a result, some inexperienced bike shops ended up installing the forks incorrectly. Read the entire forum postings on this link [Slow Twitch], its long but gets interesting as it flows.
If you or anyone you know have these forks on your Cervelo, be concerned. Cervelo has apparently not recalled these older forks (newer forks have different inserts) and many people could be out there still riding with them, it seems.
Wednesday, May 28, 2008
4 Wolf SL Fork Failure
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Carbon composites don't belong on bikes. Give me steel!
ReplyDeleteThere. I said it. I'm so retro-grouchy.
Brian-j,
ReplyDeleteI have 3 bikes - one steel retro rocket, an absolutely amazing ride, a stiff trek fixie (AL) and my primary specialized AL race bike. But ur views are not shared by many people - I don't mind a little carbon here and there but I will stick to the medium modulus stuff. The 6000+ UHM monocoque bike is not for me. Besides, regarding this fork, the fact that the spacers were made of carbon is just ridiculous. The Al spacers work just fine.
I think the market for carbon is largely for people who :
1. have the money to shell out
2. don't care if durability is on the low side (or they have no idea about durability)
3. are largely ignorant about steel,al and ti due to some crap they read online.
4. more equipment centric (worried about every damn thing from the weight of shifter cables to carbon composite bottle cages) than riding centric, if you know what I mean! The former takes some of the passion away I think...feel free to argue with me.
I experienced the same type of failure, as the fork cracked just at the base of the aluminum insert. The installation was correct (per manufacturer's instructions) and I ran no spacers.
ReplyDeleteI've since switched to the CL fork (steel steerer) and actually found Cervelo helpful in the process. I wouldn't go back to the prior version . . . there is clearly an unresolved design issue.
Regarding no spacers: I was reading some info from Bontrager and they recommended a minimum of 5 mm of spacers below the stem to reduce the stress concentration at the stem/headset junction. Seems to make sense, but this stuff shouldn't be failing at all.
ReplyDeleteCarbon is expensive because that's what people are willing to pay for it. If nobody shelled out $4000 for a non-custom frame out of China, then they would dramatically come down in price.