Carbon Fibre Frame question

[1id10t]

One of my workmates has given me a Giant Cadex CFR2 to rebuild for him. However, after picking it up I noticed some of the tubes appeared to be damaged.
The top tube near the seatpost appears to have a layer of carbon fibre off it roughly two inches long by about an inch wide. It's barely a millimetre in depth. There's also a couple of similar spots on the chainstay about the size of an M&M (just putting a few down the throat and they look to be about the same dimensions).
Before I start doing anything I wanted to know if this type of damage is going to render the frame completely unusable. I know it seems like a stupid question but my mate is keen on getting it running.

 

[Walrus]

One of my workmates has given me a Giant Cadex CFR2 to rebuild for him. However, after picking it up I noticed some of the tubes appeared to be damaged.
The top tube near the seatpost appears to have a layer of carbon fibre off it roughly two inches long by about an inch wide. It's barely a millimetre in depth. There's also a couple of similar spots on the chainstay about the size of an M&M (just putting a few down the throat and they look to be about the same dimensions).
Before I start doing anything I wanted to know if this type of damage is going to render the frame completely unusable. I know it seems like a stupid question but my mate is keen on getting it running.

That sounds a bit odd, but I'd wheel it in to an LBS who sell carbon frames and get their opinion. A friend of mine recently found a crack in his Trek 5000 and took it to the LBS who confirmed it was just the paint job. I'm not saying your issue is going to be trivial...but best to let someone who knows have a look and you might be surprised.

 

[1id10t]

Thanks for the reply Walrus. There aren't any cracks in the frame. It's just that these two sections have the appearance of a layer having come off. Guess it could just be the paint or lacquer. If it is only that then I was going to wrap that bit with some carbon look frame tape that I have.

 

[Walrus]

Thanks for the reply Walrus. There aren't any cracks in the frame. It's just that these two sections have the appearance of a layer having come off. Guess it could just be the paint or lacquer. If it is only that then I was going to wrap that bit with some carbon look frame tape that I have.

I realise there aren't cracks...but someone with some carbon failure experience (like an LBS mechanic) will be able to tell whether the missing layers are going to effect the longevity of the frame.

Good luck, hopefully they're minor blemishes and your friend's bike will be fine.

 

[sogood]

Given those are major stress bearing members of the frame, one should be utmost cautious if the damage has gone beyond the paintwork.

As for damaged carbon, is it true that repairs can be made by wrapping those weakened areas?

 

[1id10t]

Will definitely take it into an lbs. The appearance is enough to make me question its integrity. Wouldn't want to make my friend fork out some money for replacement parts only to find it the frame is damaged. Thanks again for the advice.

 

[garage sale GT]

Carbon won't always show where it's damaged, but you can get all the stuff you need to repair it with a few layers or even create a frame from scratch. If it's been knocked around, though, how do you tell it's not damaged somewhere you can't tell, as well as where you can?

 

[1id10t]

Carbon won't always show where it's damaged, but you can get all the stuff you need to repair it with a few layers or even create a frame from scratch. If it's been knocked around, though, how do you tell it's not damaged somewhere you can't tell, as well as where you can?

Yeah, good point. I can only go by what my friend says. Apparently the bike belonged to his father who used it for a few triathlons. Other than the 'damage' described the rest of it seems to be in good condition. However, as you say, under the surface is another story. I did toy around with the idea of looking for a replacement frame and just transferring the parts across. Depends on how much he wants to spend but indications are it's not that much. Don't want to overcapitalise.

 

[bobbyOCR]

Cadex frames like the CFR2 with the aluminium frok, aren't the youngest frames out there. I would be very wary as carbon has been known to lose stiffness as it nears the end of its fatigue life, if that one has been ridden much. If you do take it to an LBS, try one which you know otherwise they will have a bias towards trying to sell you a new frame. It is probaby OK, just some exterior aesthaetic carbon.

 

[dabac]

As for damaged carbon, is it true that repairs can be made by wrapping those weakened areas?

Yes, carbon can be repaired. Not invisibly, but reliably strong. One needs a good laminating epoxy, some CF cloth and the appropriate (rather basic)tools. Sand down the damage and the surrounding area, apply resin, wrap in CF, check for saturation, if needed apply more resin, repeat until desired thickness is reached, allow to cure.
For a really thorough repair one can also use things like peel, breather fabrics and vacuum processing - but that's not really required.