Jim, and Kevin: Thanks SO much for this great advice! We have been struggling with this issue and are currently NOT selling carbon anything, so this may change that decision. 

Kevin, can you recommend any resources on this topic? We have asked around the local cycling community and even spent an evening social at CABDA picking the brain of "The Carbon Doctor" and never heard of this sensible test.

Laura, thanks to you too, for asking the question! Why we didn't think to just ask the 'Tank, I do not know!

Peace,
Jim

Jim Sheehan
Executive Director
Ohio City Bicycle Co-op
1840 Columbus Rd
Cleveland, Ohio 44113
216 830 2667
OhioCityCycles.org


On Mon, May 8, 2023 at 3:22 AM Kevin Dwyer via TheThinkTank <thethinktank@lists.bikecollectives.org> wrote:
Laura Brooke-

Your advice is very good. I have experience in carbon fiber bicycle repair and construction. If there are no manufacturing defects, any damage should be visible. However, it can be a little difficult to determine the extent of the damage visually. One common method to determine structural integrity is to tap the structure with a wooden dowel/peg. Uncompromised composite structures will ring; cracked/delaminated/compromised structures will sound flat or even have a slight buzz. You can compare the questionable structure tone to a known uncompromised structure(s) to compare tones. This is not perfect, but with some practice on different samples, a tech can get quite good at analysis. The gold standard for carbon analysis are radiographs and sonograms, but those are not practical in most bicycle repair applications.

Kevin Dwyer



> On May 7, 2023, at 5:24 PM, Laura Brooke via TheThinkTank <thethinktank@lists.bikecollectives.org> wrote:
>
> 
> We had someone come by our shop this weekend. They had just bought a Specialized Allez from the early 2000s with a used carbon fork. They wanted to know if it the carbon fork was safe. None of us at the shop at the time have a ton of knowledge for what to look for... we suggested:
> 
> 1. Email the fork manufacturer to ask if there were any recalls
> 2. Look for signs to see if the bike may have been in a crash and any clear signs that the fork may be damaged
> 3. Take the fork out to inspect the steerer tube and look at the races
>
> Any other advice, yall? Thanks for your assistance!
>
> -Laura (volunteer at Freeride Montpelier)
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