cracked carbon?
 

While giving my new used bike a thorough cleaning today, i saw this on the top tube

http://i7.photobucket.com/albums/y26...8/IMAG4100.jpg

And now, of course im freaking out a little bit, mostly because im not the original owner, so i wont have any warranty coverage. I know carbon is very strong, but how can i find out if this is just a crack in the paint, or if there is damage to the frame? Its a very tiny hairline crack, about 6" from the seat post. I wont care if its just the paint, but if its more, im gonna be really sad. Ive had it out on a total of 3 rides and just now saw this

hmm. maybe try... stand next to the non-drive side of the bike, putting a foot on the BB, grab the top tube with both hands on either side of that crack, and lift up enough to flex the tube, see if the crack enlarges at all, if so, its cracked, and oops, its new frame time. FWIW, frames are cheaper than the parts on them, so you can get a new/used frame-only and transplant all your stuff onto it and be good to go.

just curious, what brand/model/year bike is this?

if it is a crack it can be repaired.
i have read about this place, they do great work. from what i have heard repairs are usually around $350.

http://www.calfeedesign.com/repair/

Lol, yeah, id like to avoid any more damage. Haha. Its a 2012 cannondale supersix. The part that sucks is to replace the frame, itd cost me almost as much as i paid for the entire bike :(. I know this because i had another 6700 groupset i was going to build up a supersix, and came across this and snatched it up.

Your next stop is youe closest Cannondale dealer. There is no way to diagnose the seriousness of this crack without first hand inspection. If it's just the paint, no problerm. If it's really into the tube wall, kiss it goodby or call Calfee for an estimate.

It's an odd place for a crack to form, unless it's very close to where the seatpost ends. However cracks rarely form in paint without an underlying cause.

As for keeping it from spreading, that depends on the exact cause. You could probably buy some time with an external splint, but it'll look like crap. In situations like this, I make a distinction between an emergency repair on the road, vs. a permanent repair at home. In your shoes, I'd probably be thinking replacement rather than repair, unless I wanted to put the replacement off a little while.

Try the coin tap test but it doesn't look very much like a crack. That's also an odd place for a crack unless it was in a prior accident.

elaborate?

nevermind...after some more searching i found this...so if i'm getting the same feedback/sound while tapping with a coin at/on the crack as i am a few inches down the tube, theoretically, it should be ok? i tried it with a nickel and didn't notice any difference in sound

http://youtu.be/1KFeT0RiP8A?t=1m30s

Basically, you tap around the area with a coin, as well as in a nearby area of tubing that you don't suspect of being damaged. Damaged carbon may sound different. If not, it's not confirmation that the frame isn't damaged, but if it does sound different, it's more likely there's damage.

That's what I've always understood by the coin test, anyway.

First, I'd go to a Cannondale dealer who can give you the lowdown on your options. Folks have this notion that carbon is fragile, can't be repaired, etc. There's no way I'd "kiss a frame" goodbye with a crack anymore than an airline would scrap a composite-based airline with minor body damage. People forget that the latest generation of airliners are also made of composites, just different material blends.

Most major markets have certified shops that can repair carbon without sending to Calfee, although they do good work.

it isn't a question whether a carbon frame can be repaired, of course it can, and there are a number of people who do it every day. But it is a question of the cost, and cosmetics of a repair vs a replacement frame. That's a decision everyone has to make for himself.

Hard to see in the picture. Sure it's not the bond boundry?