Use this guide to replace the fluid in and bleed the air from your Avid hydraulic caliper brakes.



  1. Remove the wheel of the calipers you are going to bleed, and remove the brake pads.
    • Remove the wheel of the calipers you are going to bleed, and remove the brake pads.

    • Install Avid® brake block.

      • You can substitute a 10mm wide block, such as a hex key, if necessary.

  2. Levers set for a long reach may have the reservoir closed and will not permit bleeding.
    • Levers set for a long reach may have the reservoir closed and will not permit bleeding.

    • Measure from the center of handlebar to the tip of brake lever. The distance should be no more than 80 mm.

    • If present, set the volume of the caliper system with the adjusting knobs on the lever.

      • On the right-hand lever, turn knob completely counterclockwise, then back clockwise one turn.

      • On the left-hand lever: turn knob completely clockwise, then back counter-clockwise one turn.

    • Rotate the bike and brake levers as necessary to ensure an upward flow from the caliper to the lever bleed screw.

    • Loosen brake lever bolts just enough to allow you to rotate levers to different angles.

    • Install Avid® caliper piston block.

      • This keeps the pistons in position. If pistons were to move, the system would overfill with brake fluid.

    • If no block is available. substitute a 10 mm hex key.

    • Check to make sure the half-full syringe is free of bubbles and that the tubing clip is closed.

    • At the caliper, remove bleed port screw using a T10 Torx driver.

      • Screw is located in the center of the banjo bolt that attaches the hose to the caliper.

    • Remove port screw and insert the syringe into the fitting.

    • Remove screw front the bleed port near the brake lever.

    • Thread in the quarter-full bleed syringe.

      • This syringe will accept the overflow from the caliper syringe during the bleeding process.

    • Open tubing clamp clips on both syringes.

    • Hold the lower syringe to help prevent any air from entering the caliper body.

    • Push the lower syringe plunger to move fluid through the system and out into the lever syringe.

    • Inspect for air bubbles.

    • Inspect for dirty or contaminated fluid

    • Push lower syringe plunger until mostly empty of fluid.

      • Do not fully empty syringe.

    • Close tubing clip on lever syringe.

    • Leave caliper syringe tubing clip open.

    • Pull brake lever against the handlebar.

    • Secure to the lever to the bar with a toe strap or rubber band.

    • At lower caliper syringe, push plunger gently to pressurize the system, and then pull back on the plunger.

    • Repeat this process three or four times to pressurize and then apply a vacuum to the caliper.

    • Inspect for any air coming back into syringe.

    • Leave caliper syringe open.

    • Remove the strap holding lever, but hold it against the bar with your hand.

    • Push caliper syringe plunger and allow the lever to slowly move away from the bar as fluid flows to the caliper.

    • Close the tubing clip at caliper syringe.

    • Unthread caliper syringe and reinstall bleed port screw.

    • Clean off any fluid with alcohol or soapy water.

    • Open tubing clamp of syringe at lever.

    • Pull back on the plunger to create a vacuum, then push the plunger down.

    • Pull the brake lever slightly and allow it to snap back to help purge any bubbles remaining in lever body.

    • Repeat this process 10 times, or until no more bubbles appear in the tubing.

    • Push the plunger gently as lever syringe is unthreaded from lever.

    • Remove the syringe and install the bleed port screw.

    • Clean up any spilled fluid with alcohol or soapy water.

    • Reinstall brake pads and wheel.

    • Pull the brake lever to bring the pistons to the rotor.

    • Lever should feel firm when pulled with force.

    • Repeat bleed if necessary.

    • Empty the syringes into an appropriate container and store them with their clamps open.


To reassemble your device, follow these instructions in reverse order.

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