On Wednesday, May 24, 2017 at 10:01:24 AM UTC-7, jbeattie wrote:
On Wednesday, May 24, 2017 at 8:00:17 AM UTC-7, Ralph Barone wrote:
jbeattie wrote:

snip
You're just guessing. Actual testing shows CF has better fatigue
resistance than aluminum or steel by a wide margin. Modern CF can be very
durable. https://www.pinkbike.com/news/santa-...-test-lab.html

Everything breaks, and YMMV, but making up facts about the life
expectancy of CF is not a good thing. If you claim that CF testing is
"false," you should post a link to "true" testing.

-- Jay Beattie.

However, from the same link, note the different failure modes of Al and CF.
Aluminum bends and carbon fibre snaps, which is probably why Santa Cruz
designed their carbon frames with a higher safety factor. As with nearly
everything else out there, the correct answer is probably "It's
complicated..."

Well, its also complicated because the failure mode in a crash or massive front end over-load rarely matters because the rider is ejected. In the Santa Cruz tests, both the aluminum and CF bikes were trashed. No matter what material was used, the rider is walking home -- assuming he or she can walk after hitting the rock, wall, tree, etc. and getting thrown off the bike.

IMO, what matters is fatigue resistance and low energy impact resistance -- where the rider would not be ejected but for the failure, e.g., JRA fork or front-end failures. I have been riding on CF forks for 30 years without any problems, so I'm not overly concerned, but that doesn't mean one should not be concerned. That concern can be addressed in great part by buying CF forks from reputable manufacturers and not from some Chinese "company" (workers using molds and scraps after hours) that sells on eBay.

For the first two of my CF forks that may very well have been the problem especially since the IRS for had one side not glued to the fork-head at all. The way these things were built you smeared the resin on and pushed it over the fork-head and then it was held on with a rivet until it set.

But the Colnago could only be attributed to being too light for the applied forces.

But being too light is probably the name of the game with CF.