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I have a FSA Carbon crank where the thread/bolt for my pedal has become lose and wobbles.

In all fairness the crank has has 20,000KM on it. Can it be repaired, can I replace just the crank, or do I need to replace the entire crankset?

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  • I'd try to have it replaced on warranty, since this is something that should not occur with normal use, accident, fall or pro use excluded.
    – Carel
    Sep 11, 2015 at 16:57
  • Have you tried re-tightening the pedal ?
    – Bibz
    Sep 11, 2015 at 17:20
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    I already took the pedal off and my first thought was the bearing in the pedal was gone (not the first set of pedals I've gone through).when I took the pedal off, I noticed the thread facing towards me wiggles, the side closet to the bike seems fine. I can easily wiggle the side facing me and I see a small gap between the thread and the carbon crank. The threads are fine, it's not striped.
    – HansF
    Sep 11, 2015 at 18:31
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    What you're saying is that the threaded metal "insert" that was fused into the end of the crank arm is wiggling relative to the rest of the arm? (Vs the threaded end of the pedal wiggling relative to the "insert".) Sep 12, 2015 at 2:48
  • You're correct the metal insert (threads) moves around. What's interesting is not on just one spot, but appears to be quite symmetrical.
    – HansF
    Sep 14, 2015 at 14:39

3 Answers 3

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The FSA Warranty is 2 years on cranksets.

I would still contact them to see what they recommend.They might be able to repair, recommend a company who can repair or offer you a lower-cost replacement. You didn't say which crank arm it is but they may also be able to provide a replacement for just that crank arm.

I would also stop using the crank for now for two different reasons:

  1. In the event this is repairable, you don't want to make the current damage any worse as it could tip things past the point to where it is no longer fixable.
  2. You don't want to risk catastrophic failure of the crank where the threaded insert breaks completely out of the crank taking the pedal and your control of the bike with it.
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    I've stop riding the bike, and switched to an alternate bike, In my youth, I had a pedal fall off and strip the treads, and I didn't what to repeat that nightmare, hard to pedal bike on one side.
    – HansF
    Sep 14, 2015 at 14:36
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I would try the warranty route first as @Carel suggested. It is possible that the movement has done enough damage that repair is not possible. I would consult a shop that specializes in Carbon Frame repair. They may be able to reaffix the threaded insert into the arm. As carbon parts are becoming more common repair of what used to unrepairable parts is also becoming more common.

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  • Do you really think the part would be under warranty? It's 4 years old
    – HansF
    Sep 11, 2015 at 21:12
  • Some may not offer direct replacement but they may at least give you a discount on the replacement. Many frame manufacturers offer crash / collision discounts. It can't hurt to ask. Go directly to FSA not your local shop. The discount may not be worth anything though as many times you can get it cheaper at discount sites on line.
    – mikes
    Sep 11, 2015 at 22:30
  • I contacted the bike shop I purchase the bike at and they said they would see what they can do.
    – HansF
    Sep 14, 2015 at 14:40
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While the recommendation to consult a carbon frame repair shop is sound, I suspect the answer would have been no. My reasoning is as follows.

There's a metal insert that's bonded to the carbon structure for the pedals. "Bonded" means glued, but remember that we aren't talking about the glue you'd use in arts and crafts. It's an adhesive like the one that holds the carbon fiber sheets in the structure themselves together.

If that insert came loose, it could potentially be re-bonded to the cranks. However, it could also have been fretting (NB: not 100% sure this is the correct engineering term) against the rest of the carbon structure, so it could have enlarged the hole it was bonded in and maybe damaged some fibers. That would have compromised the structure. If that were something that was repairable, it may have rendered it uneconomical.

20,000 km isn't actually very long for a crankset. FSA would not have been obliged to warranty the item, but it's still possible they might have. Shimano has been more generous with the warranty terms on it's 6800, 9000, 8000, and 9100 cranksets, where there have been some issues with the halves de-bonding (NB: aluminum crankset, so different engineering problem, but maybe similar business principle).

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