I bought a TREK FX SPORT 5 a couple of weeks ago and I've ridden it like 200km without any problems.

Today was the first time I biked when it was raining and I noticed after like 100 meter that there was some kind of scratching noise coming from the front disc. I stopped and looked for dirt/whatever but couldn't see anything.

The noise continued for the rest of the ride and I also noticed some screaming when breaking (only from the front brake).

When I got home I cleaned the bike and let it dry and now there are no sounds coming from the front brake and the wheel spins really good.

So, what do you guys think happened here? It felt like as soon as the brake/disc got wet, it started to make a "scratching" noise. Is there anything I can do to prevent this in the future?

  • 1
    Check out this previous question about a new bike's disc brakes rubbing; does that help? – DavidW Apr 28 '20 at 15:43
  • Thank you! Will have a look :) – JOSEFtw Apr 28 '20 at 18:28
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    Does this answer your question? Why do my disc brakes squeal when wet? - Many other questions have been asked over the years, please use search (hint - may help to put organic, metallic and sintered in the query) – mattnz Apr 29 '20 at 0:42
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    No sorry, I've looked at that issue and my issue is more about that the pads are rubbing when wet, it sounds like a scratching noise, not squealing :) – JOSEFtw Apr 29 '20 at 6:27
  • Next time you ride in the wet, stop and see if the noise is the same when the wheel spins backward. Also see if the noise drops off as you slowly squeeze the lever or if it just stops hard. Have a very close look at your rotors too - looking for any kind of defect that pokes up. Finally, try and see if the scratch noise is continuous, or if its when the wheel is at a specific point in its rotation (that indicates that a specific sector of the rotor is causing the noise) – Criggie May 1 '20 at 4:01

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