Added sources and updated by the Pedalwise team
Brake bleed kit · Nov 8, 2026, 9:58 PM by Pedalwise team · reviewed Nov 8, 2026, 9:58 PM by Pedalwise team
What changed
The text is the same as the version before.
This version
A brake bleed kit lets you push fresh fluid through a hydraulic brake to remove air. It must match your brake's fluid type.
A brake bleed kit is a set of syringes, hoses, adapters and a funnel used to flush fluid through a hydraulic disc brake and push out air. Park Tool's Shimano guide lists a syringe and holder, a bleed funnel with stopper, adapters and hoses as kit parts (Park Tool bleed guide).
What it's used for
Air in the system compresses, so the lever feels soft when you pull it hard, and dirty fluid should also be replaced (Park Tool). A bleed fixes both. After a good bleed the lever should feel firm (Park Tool).
What to look for
- A kit for your brake's fluid. Park Tool says never use DOT fluid in a brake designed for mineral oil, or the reverse (Park Tool).
- Adapters that fit your brake model. Procedures differ, so check the brake maker's site, such as si.shimano.com for Shimano (Park Tool).
- The extras the procedure calls for, such as bleed blocks, a pad spreader, isopropyl alcohol, rags and a container for spent fluid (Park Tool).
Using it safely
Never share one kit between DOT and mineral oil brakes. Park Tool warns mixing fluids can damage parts and cause brake failure (Park Tool). If you are unsure which fluid your brake uses, ask a shop.
- Wear safety glasses and gloves, and put down a cover for drips (Park Tool).
- Keep pads out of the way. Park Tool notes brake fluid can ruin pads and is often hard to see (Park Tool pad guide).
- Dispose of used fluid according to your local waste authority (Park Tool).
- If the procedure isn't working, contact the brake maker or a shop (Park Tool).