fiataccompli

I have an early 2000s Colnago CT-1 (titanium with carbon fiber stays). I got the bike from I suppose the 2nd owner and it probably has seen the better part of 20K miles prior to my ownership. A month or so ago, I thought I heard a creaking from somewhere in the driveline and when I got home I noticed what seemed to be new (ie, I hadn't noticed them before) cracks in the top and bottom of the left chainstay immediately forward of where the carbon fiber is layed up over the dropout. Looking on the 'net I could not find any similar failures and I'm not sure if this is simply a surface issue (and maybe the creaking was a cleat because I was grinding up a 20% hill at the time) with the clear/gel or in fact a crack. I also found a LOT of how-to stuff on doing simple carbon fiber repairs so being a fierce DIYer, I am tempted to give it a try (wet sand, find crack, patch up with carbon fiber/epoxy, wrap, wet sand, buff, done). I was curious whether anyone here has seen this type or location of failure and/or has attempted such a repair. Obviously, sending it off to the experts is a viable option and probably worth in the sense that the frame is otherwise quite nice, fits and is a pleasure to ride.

Here are some pics of it....

from the top...




from the bottom...


and, for perspective, the bike...


Thanks for input, tips, experience, etc.

StanSeven

Those look like surface scratches. Take your rear wheel off and tap the area with a coin. If you hear a buzz, it's a crack. If it makes a solid click noise, you're fine.

If it bothers you, take it to a shop.

Lots of people here have patched bikes and posted about it. I wouldn't do it myself though.

JTGraphics

I's also say from the photos although it's hard to see looks more like just the surface.
If you sand do not take it down to the fiber layer!
If you are not sure take it in and have it looked at.

math is fun

looks like a surface scratch to me. If you are still worried I would wrap it with some carbon tape and epoxy. This should be a relatively easy repair. Though, you should do a little test repair on a similar shape object if it is your first time doing wet lay up.

fietsbob

clear lacquer on a Q tip should spot finish the surface.. you could mix up some epoxy and daub it on,
Less attractive, as wisdom would leave it proud , bead like on the surface.

ultraman6970

I agree, that doesnt look cracked but more like surface scratches, sand lightly with 600 grit, and re clear using CAR clear coat. OR maybe tamiya clear coat, tamiya clear coat can be thinned using water or rubbing alcohol so it should be safe for carbon. I would not use rattle can clearcoat because of the solvents in the development of the lacquer, besides wont cure in at least a month or more. Tamiya will dry and cure in 24 hours, so it will be ready to go.

I have not used this one ever but it should work, nails clear coat.

Good luck.

jimc101

Have used Clear Nail Varnish works as well

fiataccompli

OK...that all sounds encouraging, but it seems incredibly unlikely it would become scratched in a spot that was symmetrically located along the tubing, right? My thought on some light sanding was to see if the appearance of a (surface?) crack persisted. It may be that this area is actually still a spear (for lack of a better word for it) of aluminum where the carbon fiber lay ups begin.

Anyone seen carbon (or any material for that matter) fail/crack in this location?

thanks for the feedback.

jimc101

If you look through Busted carbon https://www.bustedcarbon.com/, you will no doubt find a picture of a failure of the rear stay, but it will be a little more dramatic than the crack you have so far.

Wouldn't say 100% that is a crack; it could just be the lacquer top coat, but if it propagates would want it checked out; has the feel of the bike changed when riding since you saw this, and when touched, does the area feel different feel now; i.e. rough or smooth?

If you have a Colnago dealer local to you, would be worth asking them for an opinion.

If it is a crack, unless you familier with carbon repair would suggest going to a professional, these guys advertise in MBA / RBA, sure there are others as well, would ask them for a quote on repair https://www.calfeedesign.com/

operator

Do NOT attempt to repair CF yourself, given that you have zero knowledge or experience with such repairs. Follow the above post ^

Chombi

Try talking with the guys at "Calfee" If anyone would know what to do or if it's even a crack, they would.....

Chombi

fiataccompli

Yeah, absolutely Calfee would be the choice. I will admit that with the research I've done on CF repair, it doesn't look like rocket science and in some senses (not the one of the repair failing and breaking a collar bone) it seems forgiving. (btw, that is NOT in any way to devalue the great work that someone like that who has 20+ years of experience can do...I would not expect to be able to do the repair with anything close to the same finesse, efficiency, etc.) So, my initial thought was I should give it a try in hopes of not being w/o the bike while it goes to Calfee & back (and, sure, saving a little money....but not when I consider the value of my time), but I suppose sending it away I would rather let someone do the whole job rather than clean up my work. I already knew this, but a call to Calfee is in order next. I think the closest Colnago dealer in ATL which is about 3 hours away. With the age and mileage on the frame, I figured it was simply a material not a product that would be eligible for support...especially from Colnago.