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Today, I went out for a ride and had a small crash. I fell down sideways, then came home and realized there’s a small paint chip (which i’m fine with it) but there’s a small dot which is the deeper one that shows some brown colour.

Did I damage the carbon?

enter image description here
Left-side of frame, opposite side to rear derailleur.

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Close-up

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    Can you tell us the brand and model of your frame ?
    – Criggie
    May 6, 2023 at 9:54
  • Is that even carbon or an aluminium piece bonded to the carbon? In any either case I wouldn’t be too concerned about that specific area. But give your bike a close look everywhere else, sometimes those small crashes can do surprisingly much damage if they hit the wrong stuff at the wrong angle.
    – Michael
    May 6, 2023 at 14:01
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    @Criggie it’s a trek emonda slr6
    – Eunice Ng
    May 7, 2023 at 9:28

3 Answers 3

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The brown kind of looks like paint or grime from whatever your bike hit. Give it a scrub with an old toothbrush and some solvent and see if it goes away.

Mostly the damage looks like surface scrapes in the epoxy resin that don’t reach the fibres. Leave it unpainted and keep an eye on the area when you do your regular maintenance.

It’s unclear from the photo if that is carbon or an aluminium insert for the dropout area. The grey stuff looks kind of metallic in which case feel free to give it light sand down and some maybe touch up paint.

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From the single picture it's hard to tell definitively, but tentatively I think you'll be fine.

Best to get a mechanic have a look in person though.

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  • i’m not sure either but i’ve painted with some nail polish, the guy works in a bike shop indicated that it should be alright but i’m a little worried still as they just look at it with one glance 😅 @lamar latrell
    – Eunice Ng
    May 7, 2023 at 9:32
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Based on Trek's published stats then your bike has

Frame: Ultralight 700 Series OCLV Carbon, ride-tuned performance tube optimisation, E2 tapered head tube, BB90, direct mount brakes, internal cable routing, DuoTrap S compatible, Ride Tuned seatmast
Fork: Émonda full carbon, carbon E2 steerer, carbon dropouts, direct mount brakes

The only mention of dropouts is the carbon ones in the fork. There is no mention of dropouts in the frame.

Looking at your photo shows a definite grey/silvery metal which is unlikely to be steel, but definitely could be aluminium.

Carbon Fibre is not good at taking a thread, so common practice is to use an insert which is bonded into place with epoxy. Your bike probably has a metal end piece to hold the through axle and join the seat/chain stays.

I would lightly smooth off the ridges with a light sand, then clean well with IPA and dry, then apply 3-8 light coats of nail polish that match your bike.

Nail polish dries quickly, and there's a good chance you can find one that approaches the existing paint. Keep the unused polish for other future touchups.

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