Repairing Cracked Carbon Fibre

justfortherecor

Hey guys,

I recently came across a nice Terry Dolan carbon fibre frame left behind by a former tenant in the garage of a house. I knew the guy was a pretty serious cyclist and had a few bikes so I think he had left this one behind due to some of the damage on it.

The main problem with it is that there is a crack in the carbon fibre on the top tube. The rest of the bike is relatively fine, with the usual few nicks and scratches. I was pretty excited to find it, seems like a nice full-carbon frame, and would think about building a bike around it if it was worthwhile.

Just wanted advice first though on how serious the cracked carbon fibre would be. From my experience with Rowing, we broke a couple of carbon fibre oars and we would usually have them repaired by placing a new carbon fibre collar around the damaged part.

Would the structural integrity of the bike be affected by the crack? It doesn't seem to have spread beyond the small area on the top tube (to the naked eye anyways)

Any advice would be much appreciated, cheers.

Chris Peak

It’s F#cked - Bin it!
It’s not worth the risk. If your oar breaks again, it’s not likely to throw you into on coming traffic.
As far as I know, you can fix some cracks. But, the wear and tear from the road vibration can make it a complicated and expensive option.

Chips Lovell

Don't ride it.

There are people who repair damaged carbon frames, like Calfee in the States. Haven't heard anyone who does it here. You could look into getting it repaired, but the cost of shipping it back and forward along with the cost of repair might be signficiant.

Hungrycol

The crack on the top tube is the only one you see. I'd chuck it in the bin or make something handy (ornemental) from it by cutting it up. I wouldn't but my life between it and the road.

flickerx

justfortherecor wrote: »

Hey guys,

I recently came across a nice Terry Dolan carbon fibre frame left behind by a former tenant in the garage of a house. I knew the guy was a pretty serious cyclist and had a few bikes so I think he had left this one behind due to some of the damage on it.

The main problem with it is that there is a crack in the carbon fibre on the top tube. The rest of the bike is relatively fine, with the usual few nicks and scratches. I was pretty excited to find it, seems like a nice full-carbon frame, and would think about building a bike around it if it was worthwhile.

Just wanted advice first though on how serious the cracked carbon fibre would be. From my experience with Rowing, we broke a couple of carbon fibre oars and we would usually have them repaired by placing a new carbon fibre collar around the damaged part.

Would the structural integrity of the bike be affected by the crack? It doesn't seem to have spread beyond the small area on the top tube (to the naked eye anyways)

Any advice would be much appreciated, cheers.

I had a crack in a frame that rob1891 gave me, and tried to weld it back together (didnt really know what I was doing to be honest), but I should have used a band of metal around where the crack was. There's some photos of the frame pre and post weld in this thread.

I'd say give it a go, and see how it holds up, but maybe the others might be right about it being a bit dangerous. My problem is that I'll ride anything.

(cue bicyclegadabout double entendre sniggering)

Quigs Snr

Used to row myself and I agree, Oars are one thing, bike frame another.

Two words for you my friend:

Bin Tag.

Unfortunately.

justfortherecor

Thanks for the speedy input guys.

Looks like I'll refrain from attempting a repair so, probably the safest option. I can understand why he maybe left it behind now!

Ah well, probably just buy a bike on ebay soon enough instead once the current frenzied bids for road bikes during the tour de france dies down.

Thanks for the help guys.

blorg

I don't think you'll get far welding a carbon fibre frame flickerx

I'd bin it, in fact I already have (my Trek 5000, which was still rideable but had a small crack in the downtube.)

Fion_McCool

I'm no expert, but I found this page about frame repair online

http://www.faqs.org/faqs/bicycles-faq/part3/section-44.html

Basically it agrees with the majority view above...

SUMMARY "Damaged steel frames can always be repaired, but if the damage is severe, be sure to check your other options. If the bicycle isn't steel, then it probably can't be repaired."

Hungrycol

Avatar Police here. justfortherecor... That's Caroline_ie's avatar please use another Mr Men

Gavin

I'm a bit bemused. Are these carbon bikes really worth it ? I mean, crashing is a reasonably high probability and if as yee say it's a case that the frame may be damaged without visible cracks, then replacing must be a regular occurance?

Or does it actually take quite a bad crash to damage them?

Chips Lovell

Verb wrote: »

I'm a bit bemused. Are these carbon bikes really worth it ? I mean, crashing is a reasonably high probability and if as yee say it's a case that the frame may be damaged without visible cracks, then replacing must be a regular occurance? Or does it actually take quite a bad crash to damage them?

The reason carbon is used in bike frames that not only is it light, but it is also very, very strong. All frames can fail, no matter what the material.

Hungrycol

Verb wrote: »

Or does it actually take quite a bad crash to damage them?

Yes carbon fiber's strength is under estimated. The difference being that carbon fiber failure is dramatic whereas metal will bend. A lot of pros don't use carbon handlebars for that reason.

blorg

Verb wrote: »

I'm a bit bemused. Are these carbon bikes really worth it ? I mean, crashing is a reasonably high probability and if as yee say it's a case that the frame may be damaged without visible cracks, then replacing must be a regular occurance?

Or does it actually take quite a bad crash to damage them?

It takes a bad crash, generally the sort that would write off any frame.