Bleed Hydraulic Brakes

Steps

1. Prepare the Workspace: Secure the bike in a stand. If possible, remove the wheels and brake pads to avoid contamination; install a "bleed block" in the caliper to hold the pistons in place.
2. Level the Lever: Rotate the brake lever on the handlebars so that the bleed port is at the highest point of the system.
3. Connect Bleed Syringes: Following your specific kit's instructions, fill the syringes with fluid, attach the hoses, and purge any air from the lines. Thread the syringes into the lever and caliper bleed ports.
4. Push Fluid Through: Gently push fluid from the caliper syringe up toward the lever syringe. You should see air bubbles appearing in the lever syringe.
5. Cycle the Fluid: If the system is very dirty, you may need to push fluid back and forth several times (carefully!) to ensure all air pockets are dislodged.
6. Flick the Lever: While bleeding, gently flick the brake lever. This helps move stubborn air bubbles trapped in the master cylinder.
7. Close the System: Once no more bubbles appear, close the bleed port at the caliper first, then remove the syringe from the lever and replace the bleed port screw.
8. Clean Up: This is critical. Use isopropyl alcohol to clean every surface that might have touched brake fluid. Brake fluid (especially DOT) is corrosive and will ruin your pads or paint.
9. Test the Feel: Reinstall pads and wheels. The lever should feel firm and consistent. If it's still "mushy," you may need to repeat the process.

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Tips

• NEVER mix Mineral Oil and DOT fluid. They are not compatible and will destroy the seals in your braking system. Check the text on your brake lever for the correct type.
• Keep a bottle of water or isopropyl alcohol handy to immediately neutralize any spills on your frame or floor.
• Patience is key. Rushing a bleed often leads to trapped air and a repeat of the job.