Originally Posted by
PeteHski
We used to get similar claims from F1 drivers about their carbon chassis losing stiffness after half a season of racing. Having torsion tested numerous chassis, there was never any evidence to back up those claims. It was just a mind game to rationalise defeat. Funnily enough they rarely complain when winning. I expect it’s the same with pro bike racers.
A carbon structure will basically maintain its strength indefinitely unless physically damaged. Which can of course happen with even relatively minor accidents. I’ve also seen carbon frames snap at the point where they had been clamped on the team car roof. There was a thread here a few years ago about a Ridley frame that had broken like this. It had broken while riding along about half way up the seat tube with no obvious stress point. Someone then posted a photo of the bikes clamped on roof racks in exactly the same place where it broke.
Here ya go:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6829243/
and
https://www.limit-fatigue.com/limit-...-life-fatigue/
and
https://iopscience.iop.org/article/1...8/1/012017/pdf
I was under the impression that CF had no known fatigue limit, but that's because I was dealing with overbuilt structures which were designed for minimal flex. One assumes that quality CF bike frame manufacturers put strain gauges on their test frames when they hand them over to the test riders, so they're not just going by feel. The idea is that a good CF bike frame doesn't flex in such a way as to absorb power from the rider. When I got my CF frame in 2000, I noticed a huge difference in my ability to accelerate it compared with the 80s steel frames I had been riding, which felt like I could rip the bars off in a sprint. Otherwise known as stiffness. I would assume that a CF frame optimized for weight rather than stiffness would have a shorter service life. Obviously, pros look for a balance there. BTW, steel frames have a shorter fatigue life than CF if stressed similarly.