Is my carbon frame knacked?

[John ....]

I got hit by a car on Thursday night. Bike initially seemed fine, but having checked it more thoroughly this morning there is a faint grey mark across the left hand seatstay about 1 inch below where it joins the seat tube. When i run my finger down the tube there seems to be a very faint indentation. The tube isn't cracked at all and I've sat on the bike without it flexing. Is this serious. Would my LBS have any way of checking if it is likely to break?

[Robert Inman]

I had a noticeable hair-line crack on my seat tube (carbon). My LBS said there was no way of knowing if it was cosmetic (ie. paint) or structural. I had to send the frame back to Bianchi. It took three months for a response! In my case they replaced the frame. However, they supplied a complete frame set with a damaged carbon fork. It looked like it had been bashed against something. There was paint missing, and the weave looked a bit iffy to me. This time (as it was free, and therefore no chance of a replacement) my LBS said fine, ride it. And I have been.I'm sure there will be more knowledgeable people here, but my experience has been one of continued tentative riding to no ill effect. Fingers crossed.

[VLAD]

What.I would of sent it right back again.or at least got the LBS to swap the forks over with another model.Ever heard of Customer rights etc.Make a noise and it works.VLAD :}

[Robert Inman]

Hi Vlad. Bianchi supplied the frameset, not the LBS. The fork was an admin mistake. I should never have been sent it. I still had the original fork from the first frameset. I figured it was fair recompence for the inconvenience.I don't know, can you complain about something you shouldn't even have had? Besides I'd been 3 months without a bike and wasn't in the mood for any more hassle. I'd have ridden it even if I had to sellotape it together! Bob

[2manyYorkies]

My Madone frame got damaged in the van after the Etape last year. There was loss of paint down to the carbon on the downtube, about 3cm long, but what got me the new frame (on the insurance) was the hairline crack underneath which, although less dramatic lokking, actually went deeper and right into the carbon itself. The LBS wrote a statement saying it was no longer roadworthy and the insurance coughed (and got it back from the French van driver who had admitted liablility). The problem with carbon is it just goes" from underneath you if there is a weakness in a significant part of the frame. Having said all that, I've just re-read your opening statement again, john..., and I can't see what type of frame you have. Did you get the details of the car that hit you for insurance purposes?"

[2manyYorkies]

PS and then I re-read the title of your thread and noticed the carbon" bit, so my ramblings weren't totally irrelevant!And when i said it "just goes" I meant if it's badly damaged enough that it could disintegrate, it can do it without warning.Mind you, Lance rode and won a mountain stage on a bike that had a transected chain stay after being knocked over by a supporter (accidentally). Just goes to show how impressively stiff the top-end beasts are!"

[John ....]

Took it to the shop yesterday and the frame is dead. What actually just looked like a little scratch on the top tube was in fact a crack caused by the handlebars hitting it so the frame is a total write off. Bugger! Further advice would be appreciated on my ne thread Claiming against someones car insurance""

[Richard Hallett]

If you hit carbon hard enough to make the layers of fibre come apart i.e. 'delaminate' so there is no bond between them a huge part of the strength and stiffness of the material is lost, even though there may be little visible sign on damage. It is possible to test for damage, but this involves comparing the stiffness of the suspect part with a new and trusted example of the same thing. If there is no appreciable loss of stiffness i.e. they are within, say, 1% of each other, then the suspect part is safe. This test should be within the capabilities of any carbon frame manufacturer, but not the local LBS.

[John ....]

In this instance it is definitely bust. What appeared to be a scratch on the top tube could be pressed in with very little finger pressure. It is very flexible and basically you could probably snap the top tube between your hands if you really wanted to.

[John ....]

The damage was caused by the handlebars spinning round and hitting the top tube in the fall. Didn't seem like much at the time but they must have given it a hell of a whack.

[Burton Lumley]

Isn't there usually what's known as a UT" layer which is cosmetic on carbon components? We use an awful lot of carbon in the industry I'm in and you'd be suprised at what looks like substantial damage is actually only in the cosmetic layer. It's also possible to have carbon inspected using an ultrasound type device. It would need to be unpainted carbon though.It does sound like you have got a bit more damage than purely cosmetic though.I have chipped the chainstay on my Bianchi 928L when the chain dropped off the inner ring, been riding it for 2 years and it hasn't snapped yet........."