I'm experiencing rotor rub in both my front and rear brakes. This will only occur when wet. So for example after adjusting the caliper by loosening the mount bolts pulling the brake and tightening I can eliminate all rotor rub. If I splash some water on the caliper or rotor they start to rub/grind. Why does this happen?

  • 1
    Are you sure they're not rubbing when they're dry? How are you verifying this happens?
    – Batman
    Jun 17, 2016 at 14:05
  • 1
    This happens to me too pretty regularly in the rain. Does the rubbing start when you just "splash" water (i.e. clean tap water) as well as ride in the wet, or just when riding in wet conditions?
    – ebrohman
    Jun 17, 2016 at 18:14
  • In the rain or splashing clean tap water will have the same effect. Silent rotation, add water instant grinding noise.
    – Robaggs
    Jun 17, 2016 at 21:51
  • @Batman there is no noise or sign of rubbing when dry. The wheel spins freely.
    – Robaggs
    Jun 17, 2016 at 21:53

1 Answer 1


I have notice the same phenomenon. If you keep washing with clean water the rubbing noise should go away. My best guess is that the water coming off the tires and falling into the brakes brings a fine road grit into the system. This coats the pads/rotors reducing tolerances, causing rubbing to be more noticeable.

If it is really wet for a long time, the rubbing will accelerate pad wear (which I found out during an insanely wet Dec last year).

  • Unfortunately clean water is causing the issue also. It's a cyclocross bike that gets cleaned about 3 times a week with a pressure cleaner.
    – Robaggs
    Jun 17, 2016 at 21:58
  • The pads and disc itself produce grit that is moved around by water.
    – ojs
    Jun 17, 2016 at 22:42

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