I have a carbon frame that's is more than few years old and it has a 3' long crack? you can feel it with your finger nail in the top tube. It's more easily described like the paper tube was creased and the turned out again and the crease is still visible. The crack seems to go through the clear coat but no all the way through the fiber. It's been visible and has not really changed for apx a year or so when after a rainy ride I noticed the if you looked at the frame from the side the wet has high lighted what lookes the crease running from nearly end to end. This ghost image has no "feel" to it and when the frame dried and after not riding it for a month out of fear it has faded. So the big question is... Is the frame cracked or is it a clear coat defect? Can it be repaired? I've seen adds for kits to "wrap" carbon tubes with resin and carbon fabric that claim to be as good as new. Or is a simple sanding repair of the clear coat possible?

No one has any ideas? Maybe I should try the frame builders forum?

What's "corbon"? Is it anything like "carbon"?

Chef... I know many people will move eyes after my comment but is up to you ok?? Yes u can fix it, there is a company in the UK that sells kits to fix cracks in carbon, basically they sell all the chemicals and some meters of carbon fiber cloth plus instructions (carbonmods.com). No idea if somebody sells a similar product in the US. But what I would do now is to drill a super tiny hole with at the beginning and the end of the crack to stop it from continue cracking.

Again is up to you ok? either way depending on the frame and how old is it probably would be better just go and buy a new one if you have the money. Or send the bike to calfee to get it repair for example.

Good luck

Calfee Designs is expert At repairing damaged carbon frames and can both diagnose and, if necessary, repair yours. DIY carbon repairs are for the truly expert or the truly foolhardy.

Thanks for the advise, I saw a YouTube video of this "fix" and it looked like a doable option. The crack runs the length of the tube so I'm not so much afraid of total failure as a slow lingering death. Since the frame is trash otherwise I figure the small bore holes to stop the bleeding and a fiber wrap will extend it's life. It's a beater bike I use for chip-seal roads in rain (if we ever get any again) in Austin Hill Country. So as they say Nothing ventured ...........

Bad speller, have been for years and spell-check only works in the body of a message

Chef,

Anyone who really knows much about carbon fiber will never give you an answer over the interwebz. If anyone does, you should probably ignore them. Like Ultraman said... "It's up to you."

My take:
I've been an engineer dealing with aircraft for 30 years, and I know one thing. We would never use a material like carbon fiber as a structural material in an aircraft because of its failure mode. When carbon fiber fails, it does so suddenly and often without warning. The aircraft industry had the same problems with titanium when we first started using it in aircraft because titanium is lightweight and brittle. It tends to snap instead of bend. Sound familiar? It took a lot of research and work to figure out how to improve titanium and where we should use it. Other materials like aluminum or steel tend to fail more... errr... gently. And carbon fiber cannot take very much punishment before it cracks.

That's the main reason that I don't buy carbon fiber bikes... they're simply not durable enough for me. My brother is really into racing, and he bought a very expensive CF racing frame. He built it up with the best gruppo... and rode it for less than 6 months. Then one afternoon at a water stop he dropped the bike on its side and cracked the top tube in half. The simple mistake of dropping his bike while dismounted cost him a $4500 frame. He replaced that frame with another, and now he's afraid to ride the bike. That $4500 hurt badly.

So in the end, only you can make the decicion on whether your frame is safe to ride.