I tried everything

  1. Reset pistons
  2. Reseat caliper position
  3. Credit card method

Brakes become very tight after a few squeezes


I went to the bike shop twice, they reset the brakes twice, wheels spin nicely at the shop but brake pistons stop retracting once I ride home, disc rub comes back again.

Getting tired of this. How do I tell them to check if the pistons are really working? And give me a new caliper?

  • maybe consider draining some oil from the brake caliper bleed port and see if that helps. Jan 7, 2020 at 17:19
  • 1
    @Maarten-Monicaforpresident That's dangerous advice. Fluid should never be drained from hydraulic brakes. Doing so will introduce air bubbles which could make the brakes fail. Jan 7, 2020 at 18:47
  • @ArgentiApparatus if you drain just a tiny bit of brake fluid from the caliper end sucht that enough fluid remains in the reservoir in order not to introduce air into the system wouldn't that be ok? My thoughts were there might be too much fluid in the system causing the brake to rub as mentioned in the OP, perhaps this is incorrect though. would love to hear your input Jan 7, 2020 at 18:52
  • 1
    Nope. Fluid in hydraulic brakes is not something you ever screw around with. They should only ever be filled and bled according to the manufacturers manual. 'Too much fluid' in hydro brakes is not a thing. Hydro bakes have a specific mechanism to advance and retract the pistons. See my answer below. Jan 7, 2020 at 19:05
  • 1
    @ArgentiApparatus you can indeed have too much fluid. If you don't have a perfectly fitting bleed block to ensure pistons are fully retracted when you bleed, then the pressure during the bleed can force the pistons out a fraction causing the system to be overfilled.
    – Andy P
    Jan 8, 2020 at 8:47

1 Answer 1


It sounds like your pistons are failing to retract when the brake lever is released.

The mechanism used in bicycle hydraulic brakes to advance the pistons as the pads wear and to retract the pistons slightly when the brake lever is released is flexible rubber seals that surround the pistons. The seals deform as the pistons are pushed forward then pull the pistons back as fluid pressure is released.

It may be that your seals or pistons need cleaning. Check out this Park Tool video that shows how the seals work and how to clean them.

  • Thanks sounds like all the solutions are beyond my technical skills. mine is a new bike so I Guess it’s a trip back to the shop to rectify it. Hope warranty covers this.
    – temu
    Jan 8, 2020 at 13:32

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