Framebuilders - Is there a repair for carbon fiber?

I have carbon fiber seat stays, and a section is “chipped” That is the clear coating on small area is chipped. Will this weaken the frame? What should I do? Is there a repair? (1 year old bike - don’t know how it happened – no crashes)

Thanks,

Tom; If you are not comfortable with assesing the situation, take it to your LBS or the LBS whih sells that frame. Bob

Bob is right. If the damage is only to the clear coat - the problem is only cosmetic. Most clear coats on carbon are very thick to reduce the likelihood of damage to the frame. Things to look for as signs of trouble include: rub a finger over the area to determine if there is any distortion to the "tube"; look for and feel for any loose or broken fibers; look to see if the "tube" appears distorted.

if it is only the coat, and there are no cracks, JB weld

There are repairs. My dad developed some of the first two component epoxies and we made bows and a kayak together. A repair job would be ugly and uninsureable. If the lbs says no good and you can afford a new bike, get one. Save the frame though. The technology is still advancing and it might be fixed later. If the damaged section is round I would like to experiment with cutting out the bad part and putting a steel insert inside the good tubing. Much the same way metal parts are attached to CF now. Then let my worst enemy ride it.

the outer layer is mostly cosmetic, and its basically epoxy (at least it is on my 1991 cf giant frame). actually, the outermost layer of carbon fiber is mostly cosmetic too on clear finished tubes. that last layer is carefully laid out so the cf weave is parrallel to the tube direction, and they try to conceal the edges too.

i repaired my giant frame with a defect similar to the one you described (dropped a small wrench, a glancing blow to the top tube knocked off a bit of clear outer layer, cf layer was undisturbed).

i fixed it with epoxy from the home depot. comes in a dual syringe applicator. mix thoroughly, then apply. put on enough so its thicker/taller than surrounding area. may have to build up with two layers if thick.

make sure you apply it even as possible so theres no deep valleys that won't sand out.

let it dry a few days to harden well. apply tape to surrounding tube as mask to protect "good" area from subsequent repair step.

next, sand lightly with 800 or 1200 grit. when get close to even with edge of good area, start polishing with car wax or equivalent very fine grit polishing agent.

go really easy in the sanding / polishing. its easy to sand right thru epoxy with almost no effort.

if any valleys or dips at this point, put on more epoxy, then repeat sanding/polishing.

if you are careful you should get really good results. the only way i can tell where i repaired my top tube is that a graphic which was buried in the epoxy layer was damaged, so now a small part of a letter is missing. like it peeled off somehow. but the epoxy layer turned out really well.

on close examination i discovered there were some original defects in the tube finishing that are more noticeable than my homemade repair (looks like i was more careful than the taiwanese fella that built my frame).

this was a case where i guessed at a repair technique and it worked out real well. if youre fairly handy you can do this repair yourself.

As to repairs, the cosmetic can often be taken care of with clear nail polish. It may not give a show-bike solution, but you can't ride regularly and maintain a show-bike finish. Epoxy (or JB Weld) on the clear coat provides no structural advantages.

If you want a repair for something structural, several places do them. Probably the first stop should be a call to Nick Crumpton (www.crumptoncycles.com). Pez just did a nice write up on him.