I got new 2022 Trek FX 2 couple of days ago. But I noticed something on the end of the left chain stay. Are these defect and should I worry about it? Also I asked this to the local retail where I bought the bike and they said it is normal and every FX model has that. But answer didn't satisfy me because it doesn't look normal to me.

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  • My opinion, all looks pretty normal to me. Perhaps the weld underneath is a bit messy, but paint finish looks pretty good so wouldn't expect any problem. As for dimple under the brake calliper, looks pretty (although pic might be deceiving) round and smooth so would think it's a feature rather than a flaw. If your concerned, try get another opinion from an independent bike retailer in your area.
    – Hursey
    Commented Jun 7, 2023 at 23:42

1 Answer 1


I think you LBS is right, look at this picture from Trek's own website. Some manufacturers add dimples on their chainstays to increase tire clearance, your second picture makes it look as if the dimple is there to increase the caliper's clearance, but I am not really sure.

TL;DR, this is fine.

A Chainstay from a Trek FX2, showing the same bulge as OP's

  • 3
    Given the OPs pictures are of the left chainstay, and the areas in the OPs pictures are obscured in the picture you've posted, a different picture would actually support answer. Commented Jun 7, 2023 at 20:00

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