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Dropped Chain Damage

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Dropped Chain Damage

Old 09-01-22, 03:15 AM
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grn.eyed.bandit
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Dropped Chain Damage

Dropped chain at the stoplight and couldn’t unclip fast enough led me to topple over. Aside from a damaged ego, found my chain all twisted and some carbon damage.
Just wanted opinions on this damage…




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Old 09-01-22, 05:30 AM
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That looks deeper than paint deep. If you bought it at a LBS, I would have them look at it.
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Old 09-01-22, 05:46 AM
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The bottom bracket shell is the most densely layered part of the frame.
Superficial damage imo. Remove crank, sand to smooth, either add a bit of Bondo to level the area or just prime and cover with a sheet of protectant material to protect against further chain drop damage.
Unclip before the stop.
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Old 09-01-22, 06:24 AM
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I agree with Kai that it's probably not significant damage as the carbon would be quite thick there are is probably superficial and doesn't need a major repair. I'd also check the limit screws and cable adjustment on your front derailleur to ensure you won't have the same occur again.

As a side note, your large chain ring looks to be in need of replacement. Just look at the difference in the teeth vs the small ring.
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Old 09-01-22, 06:44 AM
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The damage is not significant, IMO.
You seem to have a nice bike
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Old 09-01-22, 07:21 AM
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Originally Posted by NumbersGuy
As a side note, your large chain ring looks to be in need of replacement. Just look at the difference in the teeth vs the small ring.
I think it's the steeper angle of the pic - makes the teeth on the big ring look smaller.

I agree though - the damage sucks but doesn't look A. that significant and B. not in an area that should get that much stress. Full discloser: I'm a marketing guy on a forum.

I do feel your pain though. I did a very similar thing a few weeks ago. Chain dropped and I fortunately stopped pedaling quick enough to not launch myself over the bars. But, the chain was stuck so bad I had to pull the left crank arm and nudge the drive side out a bit to make space. On the plus side, I figured out how to use three Allen wrenches to make a tool to remove the plastic preload nut. Felt like McGyver out there.
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Old 09-01-22, 08:10 AM
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I would, at the very least, keep a close eye on the frame close to the damage. If you see cracks in the paint extending out from the damage area, I would stop riding and have the frame professionally checked by someone who knows how to properly evaluate and/or repair carbon fiber.
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Old 09-01-22, 08:14 AM
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Just keep an eye on it. I'd probably smooth it somewhat and smear a drop of epoxy resin on it. Or epoxy cement which comes in the convenient double syringe. Which is pretty much the same thing as epoxy resin.

Wouldn't be a bad idea to have it checked out, but not every area and every bike shop has a person that actually knows anything about carbon fiber construction. Much less what is safe or not. So maybe get some opinions, but for sure just watch it.
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Old 09-01-22, 08:45 AM
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Like others have said, touch it up with some epoxy. Just use a little bit with a artist's paint brush. Wet sand any rough places. Then touch up the paint.

Touch up paint

Keep an eye on it.

It's not the type of damage that could result in a catastrophic failure. If there is a bigger problem, it will likely manifest in radial cracking that will be visible.
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Old 09-01-22, 09:45 AM
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Thanks for the suggestions everyone. Plan to sand it down a bit and top it off with some epoxy.

Just under 20,000kms on this bike and love it just as much as I did on her maiden voyage!

Current state after mishap:
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Old 09-01-22, 09:54 AM
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While you're working on the bike, consider installing a chain catcher. It could prevent a repeat mishap.

I like the stuff that K-Edge make, and they have a few different style chain catchers.
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Old 09-01-22, 12:49 PM
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Originally Posted by terrymorse
While you're working on the bike, consider installing a chain catcher. It could prevent a repeat mishap.

I like the stuff that K-Edge make, and they have a few different style chain catchers.
Weird thing is that this is the first time in 5 seasons that it’s happened with this bike, and it has a chain catcher that was in proper position! I had to move it to get the chain back on 🤷🏽‍♂️
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Old 09-01-22, 12:56 PM
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Originally Posted by grn.eyed.bandit
Thanks for the suggestions everyone. Plan to sand it down a bit and top it off with some epoxy.

Just under 20,000kms on this bike and love it just as much as I did on her maiden voyage!

Current state after mishap:
When you sand it, wet sand it with 1000 to 2000 grip paper. Try not to sand into the carbon weave, you just want to smooth out the roughness without breaking up the fibers in the undamaged layup. It doesn't need to be perfectly smooth as the touch up will fill in the gaps.

That comes from years of fixing carbon sailboat masts and other parts.
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Old 09-01-22, 05:21 PM
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Originally Posted by grn.eyed.bandit
Weird thing is that this is the first time in 5 seasons that it’s happened with this bike, and it has a chain catcher that was in proper position! I had to move it to get the chain back on 🤷🏽‍♂️
So the bike has a chain catcher that didn't catch the chain?

That sure seems like a crummy or improperly installed chain catcher. They normally work.
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Old 09-01-22, 07:38 PM
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Damn ive totaled a bike from a dropped chain but atleast it was almost dead. Id be so salty if i damaged a carbon frame from a dropped chain. Goodluck OP id be kinda upset if I were you but honestly it probably wont break
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Old 09-01-22, 07:39 PM
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Originally Posted by Mojo31
When you sand it, wet sand it with 1000 to 2000 grip paper. Try not to sand into the carbon weave, you just want to smooth out the roughness without breaking up the fibers in the undamaged layup. It doesn't need to be perfectly smooth as the touch up will fill in the gaps.

That comes from years of fixing carbon sailboat masts and other parts.
why would you sand it? Just the aesthetics?
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Old 09-01-22, 07:54 PM
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Originally Posted by LarrySellerz
why would you sand it? Just the aesthetics?
Because you don’t want broken and frayed carbon strands catching on things and pulling apart.
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Old 09-01-22, 10:24 PM
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Originally Posted by terrymorse
While you're working on the bike, consider installing a chain catcher. It could prevent a repeat mishap.

I like the stuff that K-Edge make, and they have a few different style chain catchers.
Thanks Terry. Just ordered one for my Bianchi carbon Infinito. Dropped the chain once and really gouged the top of the BB. Looks like the OPs gouged the bottom of the BB area.
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