Bicycle Mechanics - Damage to CF frame

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Iamkar33m
07-08-08, 11:31 PM
Just thought I might ask this here, how do you judge if a Carbon Fiber frame damage effect's the frame's structural integrity?

For example, a deep scratch in the seatstay... would that be something that renders the frame dangerous to continue riding on?

Captain Slow
07-09-08, 06:08 AM
A scratch can be superficial. CF frames are a lot stronger than you'd suspect. I've seen many frames & forks with cracked paint... especially forks... from the normal flexing that comes from use. Looks scary, has no structural implication.

That said, what you call a "deep scratch" might be described by someone else as a "gouge, trough, dent, or puncture" of the carbon tube.

Best thing to do, then, is to ease your worries. Have a bike shop look at the frame and pronounce it safe or unsafe.
Iamkar33m
07-09-08, 08:04 AM
A scratch can be superficial. CF frames are a lot stronger than you'd suspect. I've seen many frames & forks with cracked paint... especially forks... from the normal flexing that comes from use. Looks scary, has no structural implication.

That said, what you call a "deep scratch" might be described by someone else as a "gouge, trough, dent, or puncture" of the carbon tube.

Best thing to do, then, is to ease your worries. Have a bike shop look at the frame and pronounce it safe or unsafe.

The shop that looked at the gouge stated that it only cut through the "cosmetic" carbon fiber layer. They explained that there's 2 layers of carbon fiber, the structural one and the "cosmetic wrap" to make it look pretty. Is that true for a Madone?

Captain Slow
07-09-08, 08:49 AM
I don't know about the Madone specifically. I do know that most of the molded "monocoque" carbon frames do get a cosmetic overwrap so they'll have that distinctive carbon fiber pattern that we all expect to see.


Couple of suggestions...

Post a photo of the scratch, and see if any of the really knowledgeable frame guys on this forum can give any advice.

Or, go to the source. Contact Trek customer service, and e-mail some photos to the tech support person that they give your case to... Believe it or not, they're going to care about this. Dig up that bike's manual, there will be some contact info in the back... Or, have the bike shop folks do the foot work for you.