Repair guides › Brakes
Bleed Shimano-style hydraulic brakes
Lever with a master cylinder that pushes fluid to the caliper. A piston in the lever pushes mineral oil or DOT fluid through a sealed hose.
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Tools
- Ball-end hex key set (1.5–10 mm): Park Tool HXS-1.2 Professional L-Shaped Hex Set ($$)
- Shop rags + nitrile gloves: shop towels and nitrile gloves ($)
- Isopropyl alcohol 91%+: isopropyl alcohol 91% ($)
- Brake piston/pad spreader: Park Tool PP-1.2 Brake Piston Press ($)
- Shimano bleed kit + mineral oil: Shimano bleed kit funnel and Shimano mineral oil ($$)
- DOT bleed kit + DOT 5.1 fluid: SRAM DOT Standard Bleed Kit ($$$)
Compare Good, Better and Best for each tool
Steps
- Use only the brake fluid printed on your lever or caliper. Mineral oil: Shimano, Tektro/TRP, Magura, and SRAM Maven, Motive and DB8/DB6/DB4 (marked mineral oil). DOT fluid: most older SRAM/Avid (Level, Code, Guide, G2), Hayes and most Formula. Never mix them or share a bleed kit: the wrong fluid destroys the seals and the brake fails. Wear gloves and safety glasses.
- Remove the wheel and pads (keep the pads away from fluid), push the pistons fully back, and insert the bleed block.
- Level the lever, remove the bleed screw, screw in the funnel with some of the correct fluid. These steps are the funnel bleed used by Shimano, Tektro and most TRP brakes. SRAM, Hayes, Magura and Formula use a two-syringe bleed: follow the maker's bleed manual and kit.
- Fit a tube + bag to the caliper bleed nipple and open it 1/8 turn, and squeeze the lever gently to start the flow. Let fluid flow down from the funnel until no bubbles come out of the tube. Keep the funnel topped up so it never runs dry (that pulls air in). Close the nipple.
- Flick the hose and squeeze the lever to burp bubbles into the funnel.
- Plug the funnel, remove it, top off, refit the bleed screw.
- Clean the lever and caliper with alcohol (if fluid touched the pads, replace them and clean the rotor). Refit pads and wheel, close the QR (or torque the axle). Bed in.
- Squeeze the lever: it must be firm and stop well before the bar. Test both brakes at low speed before riding.
Diagram
Cut in half, looking down from aboveDisc brake caliper (either wheel)
Signs it needs doing
- Spongy lever (air)
- Lever pulls to bar (needs bleed or pads)