Carbon Fiber Frame
 

My seven year old back-up bike has a carbon fiber fork and seat stays. Over the years, it has developed several small chips and scratches. Is this anything to worry about? I know (on commuter bikes) that C.F. cause problems in these types of bikes.

If the chips and scratches are just in the paint then I wouldn't worry. If there are scratches in the CF itself then I'd start to worry, the deeper the scratch the more I would worry. I'd be less concerned about seat stays than I would forks.

I don't see it as much here but in the classic and vintage forum people would post pictures of dents and creases in their steel tubes bikes wondering if they need to be concerned our not. Most of us have some degree of experience with steel. A big crease means a tube is more likely to buckle. A small crease wouldn't be cause for concern, but lots of creases fall in the middle and you get various opinions.

The problem with CF is that very few people have real world experience with what it takes to weaken CF to the point where it's in danger of breaking. And while we all understand steel tubes pretty well, there are lots of ways to make CF tubes that can cause them to be stronger or weaker. CF fork blades that look similar to each other can be quite different in terms of resiliency depending on how they were made.

You might have to take it to a bike shop and have them tell you.

You can now justify buying a new Bike.

It gets very confusing and frustrating when considering if a carbon fiber part has sustained damage enough to be considered. I wish that I knew of a manufacture that has results of different degrees of damage and how likely it would be to cause a component failure.

As it is, there's just the forum experts. Generally they are most expert at expressing their opinions and nothing actually factually based on dependable research. "A scratch in a CF part demands replacement for safety reasons before it suddenly fails." How safe a statement could someone make??? What sort of damage do they consider to be a scratch?? What one might consider a "nick" is probably a "gash" to others.

I had a friend that knows nothing about bikes call me concerned about one of his employees. My friend is very knowledgeable and involved with high end cars, up to and including Formula One development and repair. One of his key employees had just purchased a CF mountain bike. My friend, knowing nothing about bikes but familiar with CF of performance cars, was worried about his employees safety. See....no facts, just worries.

Like tjspiel, I wouldn't be, and am not on my own bikes, concerned with clear-coat nicks. As long as there is no frayed fibers it's of no concern to me. To be honest, I don't have a full CF frame bike. I do have one with CF seat stays, fork/steerer, stem, seatpost and bars.

Basically if it were made of fiberglass and it wouldn't bother me, I don't worry about CF. My biggest fears are steerer/stem failures.

YMMV and probably does.

Perfect!!:roflmao:

:beer:

Take it to a reputable bike shop that has people who understand carbon fibre and let them determine if your bike is safe to ride or not...Internet experts can only offer personal opinions because they haven't even seen your bike, they can't really determine if your bike is safe or not because you haven't posted any pictures of how bad those dings and scratches are.
If it was me I wouldn't even ask these type of things on internet, I would just go to one of the bike shops and let them decide.

In general scratches on carbon fiber frames are not a big deal. The only exception is when you cannot tell how deep the scratch goes. Cracks are a much more serious issue and should always be examined by someone experienced with carbon fiber.

Why are surface scratches not a big deal?

Most plastic bikes have a thick coat of clear coat.
Almost all plastic bikes have multiple layers of cosmetic surface weave.
Structural carbon fiber is stronger and more resistant than surface weave.

If you are not 100% certain how deep a scratch penetrates you need to get the bike looked at by an experienced repair shop!

That being said:

*A paint or clear coat scratch is irrelevant to safety. (I have many dozens on my oldest carbon fiber bike -- almost 8 years old.
*A scratch that penetrates surface weave is generally safe to ride but should be sealed with clear coat.
*A scratch that penetrates into structural fiber needs repair or sealing.

If your carbon fiber bikes needs repair, do not despair! Carbon is by far the cheapest frame material to repair.

I should also note that the use of aramid and kevlar in carbon fiber has made it incredibly resistant to impact. For example, many high quality carbon fiber forks and rims are now incredibly impact resistant.

This +1.

This +∞

If you're not sure about the fork, a new CF road fork is all of $100 at Nashbar. And if you really cared you could probably figure out way to get a matching rattle can of paint.

I would recommend a carbon fiber repair shop over a LBS. Most major cities now have shops that specialize in crabon repair.

For example:

Portland:
Ruckus Composites | ReMade in the USA

Seattle:
Spyder Composites | Carbon Fiber Bike Repair