Thin carbon tube, good or bad?

Discuss light weight issues concerning road bikes & parts.
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Posts: 628
Joined: Thu Jan 19, 2012 11:30 pm

by ichobi

Hey guys, i don't know much about carbon frame construction but i would like to know if a frame with rater "thin" carbon top tube is good or bad or it means nothing?

The story is that I crashed my bike (Ridley Fenix) last month due to an old grandpa thought it was fine to make an immediate u-turn before checking if there was someone behind him. So i collided head-on to him, he was fine but i landed on my back hard. My frame top tube shows a small crack around the area near seatpost. I didn't know which part of the bike collided with his bike because it crash was very fast. When i get the bike to carbon frame repairman he said this particular model has a rather thin carbon in top tube. As in you can get the flex quite easily if you press your thumb down in the TT area. He fixed another Fenix cracked at the same area i had. It can be fixed and shouldn't impact the ride feel as the crack area doesn't get much power transfer unlike, say BB or HT. My LBS said thin tube is bad though he didn't say why (it cracks easily?) and recommends I shouldn't ride a cracked frame.


Was wondering if there is any merit in what he said. I love the Fenix, it rides well an looks great. Don't want to spend anymore on this bike and i simply ride for fitness. Though I want to take any chances if it's dangerous to ride.


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Joined: Sat Dec 13, 2003 2:25 am
Location: Canada

by Geoff

If you're asking if your frame can or should be repaired, the answer is 'yes'. If you're asking if you should or shouldn't ride a cracked frame, only you can make that call. Personally, I wouldn't recommend it. You've got too much to live for, right?

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by topflightpro

No, you should not ride a cracked frame.

As far as the comments from your LBS, I think he is incorrect. In an effort to create the lightest bikes possible, manufacturers put less carbon where it is not needed. This creates thin walls in some spots.

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Location: MS, USA

by woz9683

Repair it, then ride it. It will be perfectly fine after a proper repair. I've had two ridley heliums, I've cracked both of them in the same general area (they are very thin), I've fixed both of them, and they both still ride great. No issues.

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Joined: Thu Jan 19, 2012 11:30 pm

by ichobi

I see so they reduce the carbon where it's not high-stressed (and not needed). I have sent the frame for repair already and waiting for return to build it up again.

Thanks for your info, really appreciate this. Btw Woz did you use alu seatpost? The carbon repairman said if I use carbon seatpost it might help absorb and spread the impact force, thus not cracking the frame as alu seatpost would have done.

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