Ross520

I noticed a loose fiber or two on my cf fork drop-outs when I had it off to clean and lubricate the bearings.

From what I understand, even minor damage to cf can stress it to the point of failure.

Should I be worried?

blamester

Get someone who knows what they are doing to look at it.
Lbs, engineer or competent mechanic. Someone you can trust
Have a good look yourself and try to figure it out. Be sensible
You can't cycle while worrying about a failure.

HillRider

Can you post a picture of the dropout? "....a loose fiber or two..." doesn't tell us enough.

Ross520

I will probably take it to the LBS tomorrow, figured I'd ask on here though, lots of intelligent, experienced folks on this board.

Thanks for the reply, blamester.


My apologies, I tried to take a few earlier, but they just weren't turning out very well.

I'll attempt to take some better ones later today.

Thanks for the response, HillRider.

unterhausen

dropouts are crushed regularly by tightening the wheel. Getting a few loose fibers doesn't seem like a big deal. Best to get an opinion from someone that sees a lot of carbon dropouts though

Mad Honk 

Ross,
CF doesn't like getting crushed at all. Watch any Indy car hit a wall and then tell me about crushing. Same goes for thin walled CF in golf clubs where I am certified at repairing. If the drop outs are CF and not reinforced with any other material, sooner or later they will fail. Stress will cause failure in a lot of drop out materials but in some it is less of a problem. Smiles, MH

ljsense

I have filed off the lawyer tabs on every road fork I have, including those with carbon dropouts. Team mechanics all over do the same, without any issues I know. A dropout does get worn a bit from the quick release skewer. If a few filaments are coming up here, where the skewer would be dimpling steal, it's probably not a big deal -- but you want to be sure it's not delaminating. If a big chunk is curling up above the dropout where it joins the leg, that's a problem. But again, those are just loose guidelines, and it would be good to have someone take a quick look at it, if you can find a carbon expert around, or at least a shop that deals with a lot of carbon.

HillRider

In my experience, it's later rather than sooner and, really, a lot later. I have two bikes with Easton EC90SLX all-carbon forks which have unreinforced carbon dropouts. One has 50,000+ and the other 47,000+ miles and both are apparently in excellent condition. One has the lawyers tabs worn off from wheel removal and installation and the other has them mostly intact. I have Shimano and Campy skewers and tighten them very snugly, but don't beat on them, and so far no dropout damage has been done.

easyupbug 

It is true carbon fiber in this context is strong in tension and weak in compression but the resins used to build the dropout are strong in compression and weak in tension so it is the combination of fibers and resin that supports the skewer compression loading that allows CF dropouts to be fully functional. A strand or two should not be a major issue but a minimum of photos or better an exam by someone with experience is needed.

Ross520

Okay folks, sorry for the delay. I was FINALLY able to take a decent picture that captures the strands I'm talking about. Ignore that black mark, it's just a shadow from the flashlight I was using to illuminate the strands.

HillRider

I consider those loose strands inconsequential. There doesn't seem to be any structural damage to the dropout.

Ross520

Thanks for the reassurance, HillRider. I'm quite new to carbon and can be a bit of a worrier at times.

Jax Rhapsody

Take a lighter to it.

Homebrew01

Looks fine to me.

Mad Honk 

Ross,
In looking at your drop outs I see some damage due to compression but nothing that indicates de-lamination. your pic #10 shows some compression damage that is normal for CF but the little pieces that are breaking away are inconsequential in the composite total of the drop out. The checkerboard square pattern is normal way of laminating CF together and that is intact so no problems from that and they are normal. When CF breaks down you will see the small parts that are the checkerboard pattern start to fray and that is what means the CF is de-laminating. HTH, MH

Ross520

Thanks for the reassurance, brother.

Appreciate the detailed explanation, Mad Honk. I'm a complete newbie to carbon, so it's great to learn something from folks much more experienced than myself.

Kimmo 

The EC90 forks probably aren't a good example, due to the fancy CNT business going on... I gather the resin is fortified with nanotubes.

HillRider

Perhaps that's why the forks are in such good shape after all of those miles but I haven't heard of common failures with less "sophisticated" all-carbon dropouts.

2old

Not feasible for everyone, but on my MTB with a Ritchey CF fork, I minimized the number of times the front wheel was removed (probably averaged less than once a year for ten or so years.

blamester

Nothing wrong there but you should have figured it out yourself.
I said have a look yourself and be sensible.
It's obvious that manufacturers don't make forks so close to failure that any tiny bit of damage or wear thru use can cause failure.
You could also see where the damage is that even if it cracked it would very like have held your wheel perfectly.
You might be able to save yourself from worrying needlessly.

ljsense

Yeah, that's fine. You could get rid of that tab with a nice sharp file. If you want to take off that wild hair, a little 200+ grit sandpaper and a light touch will do it in 5 seconds or so.

Carbon is not some crazy material. It's like paper mache but the paper is much stronger, as is the glue.