Stuck hydraulic brake piston

Pad stays pressed against the disc even when releasing the lever.

You can fix it · Estimated time: 10 minutes

Tools you need

• 5 mm Allen key
• Flat screwdriver (with cloth to avoid scratching)

How to fix it, step by step

1. Remove the wheel and look at both pistons. Identify the stuck one (it doesn't return to its position).
2. Pull the pads out with your fingers (they usually have a safety pin).
3. With a flat screwdriver wrapped in a cloth, gently push the stuck piston back in. Do NOT use bare metal, it scratches the piston.
4. Squeeze the lever several times so the piston moves in and out. Wipe with a dry cloth.
5. If it is still stuck, apply a drop of the caliper's brake fluid (DOT 5.1 or mineral oil, depending on the brand) to the piston.
6. Put the pads and wheel back. Center the caliper by loosening the two Allen bolts, squeeze the lever, and retighten the bolts.

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