How to bleed Shimano-type MTB disc brakes?

How to bleed Shimano-type MTB disc brakes?

For MTB hydraulic brakes that use mineral brake fluid, bleeding is necessary if you notice a loss of performance. Here is how to carry out this procedure on your MTB yourself.

  • Time: 1h00
  • Level: Difficult
  • Tools: Bleed kit / Mineral fluid / 2.5 mm Allen key / 7 mm flat spanner / Screwdriver


Steps

Reminder: Depending on the brake model, the procedure may vary. It is advisable to consult the manufacturer's manual beforehand.

  1. Replace the caliper pads with the bleed block.

  2. Position the brake lever at 45° from horizontal.

  3. Remove the bleed screw from the lever, then fit the funnel without the rod / plug.

  4. Place the syringe, previously filled with at least 10 ml of mineral fluid, onto the bleed screw of the caliper.

  5. Open the bleed screw with the flat spanner, then drain the system by pressing on the syringe. The fluid will rise up into the funnel.

  6. Temporarily close the bleed screw when you no longer see bubbles coming out at the funnel, then remove the syringe from the caliper.

  7. Now place the hose with the collection bag on the caliper, then open the bleed screw.

  8. Tap on the caliper with the handle of a screwdriver to dislodge the bubbles whilst the fluid flows through. Be careful, during this operation the level in the funnel will drop, so make sure to top it up with brake fluid to prevent air from entering the system.

  9. Temporarily close the bleed screw when no more bubbles are visible in the hose connected to it.

  10. Operate and hold the brake lever, then quickly open and close the bleed screw several times (for approximately half a second each time) to expel any remaining air bubbles. Close the bleed screw definitively before reaching the end of the lever's travel.

  11. Operate the brake lever several times to bring any bubbles up to the funnel level.
    Probikeshop tip: the lever should be or become firm at this stage.

  12. Position the lever horizontally, then repeat step 11.

  13. Remove the funnel, having previously sealed it with the rod/plug.

  14. Refit the bleed screw on the lever.

  15. Wipe away all traces of oil.

    MTB - Complete MTB Brakes