In praise of biology

Posted by lex, on August 14, 2006

Well, that’s a blow: Got a call back from UC Cyclery, where I’d dropped my bike off for a shakedown after my little car-vaulting excursion last weekend. It turns out that carbon fiber is susceptible to stress risers – bubbles in the frame – that can propagate over time into sudden, catastrophic failure modes. They’ve found flaws in the both the fork and the head tube, ugh:

Unlike steel and aluminum, which will both bend before breaking, carbon fiber just lets go. No warning, no flex, no visible cracks—just a loud crack and failure. The broken seatpost reminded us that more attention has to be paid when working and living with carbon fiber components. Budget extra time for assembly, read instructions carefully and be sure to use a torque wrench. If you scratch a carbon fiber bar, seatpost or stem (and we’re not only talking about crash damage; we’ve seen carbon bars scratched by a tie-down during transportation), trash it.

Thoughts of which would be enough to make your correspondent rather pensive on some of those steep downhills in the vicinity of North County, Coastal. Because Murphy is still on watch, and there’s just no way the head tube or fork would come apart just as he struggled to the top of Torrey Pines park, a-gasping and a-heaving at seven or eight miles per hour, no: They would have to give up the ghost at the bottom, doing thirty-five or so.

Which doesn’t sound like so very much, but really can make all the difference.

The good news is that Trek has a crash replacement program that will provide a new frame and fork at considerable discount. The bad news is that even with a discount, they’re not exactly giving them away, and there’s still labor to pay for. They’ve offered me a good guy discount for buying from there, but mechanics got to eat too.

It’s interesting that of the two carbon-based frames involved in last week’s mishap, the 45-year old one is healing day by day, while the one-year old one is headed for the scrap heap.

Still, count your blessings, yah? Could’ve been worse.

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Filed under Best of Neptunus Lex, by lex, Carroll "Lex" LeFon, Carroll LeFon, SoCal

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