How to Bleed the Hydraulic Brakes On An E-bike

Hydraulic brakes are a common feature on e-bikes, as they provide better stopping power and modulation than mechanical brakes. However, hydraulic brakes also require regular maintenance to keep them working properly. One of the most important tasks is bleeding the brake system, which means removing any air bubbles that may have formed in the brake fluid. Air bubbles can reduce the brake performance and cause a spongy feeling in the brake lever.

There are two ways to bleed the hydraulic brake, a quick bleed and a complete bleed! A quick bleed is frequently used as it is quick and easy, but a complete bleed is only applied after you use the brakes for a long time, usually half a year or one year, as it is more complicated. A quick bleed is only a temporary way to solve the brake pressure issue as it can’t empty the air in the line completely, and if you are in a hurry to use the bike or you just got the bike, you can do the quick bleed. However, if you use the bike for a long time and you need to empty the air in the oil line completely, then you need to do a complete bleed.

Bleeding the hydraulic brake on an e-bike is not a difficult task, but it does require some tools and patience. Here are the steps to follow:
(If you do a quick bleed, then you only need to do the fourth step in the below eight steps. If you want a complete bleed, then you follow the eight steps one by one!)

1. Gather the tools and materials you will need. You will need a bleed kit that is compatible with your brake model, a syringe, a wrench, a rag, some gloves, and eye protection. You will also need some fresh brake fluid that matches the type of your brake system (usually DOT or mineral oil).

2. Prepare your e-bike for bleeding. Make sure your e-bike is turned off and unplugged from the charger. Remove the battery if possible. Secure your e-bike on a stand or lean it against a wall. Rotate the handlebars so that the brake lever is level with the ground. Remove the brake pads from the caliper and insert a bleed block or a spacer between the pistons to prevent them from moving (If you operate on a BeeCool model, you don’t need to remove the wheel or insert the block but start from bleeding directly).

3. Attach the syringe to the bleed port on the caliper. Fill the syringe with brake fluid and push out any air bubbles. Loosen the bleed port screw with a wrench and insert the syringe nozzle into the port. Tighten the screw to secure the syringe. (video instruction link:https://drive.google.com/file/d/1tSvgABUsKerCvATo5o-jgDHO35hY4j2l/view?usp=share_link)

4. Open the bleed port on the lever. Remove the cap or screw that covers the bleed port on the lever and attach another syringe or a funnel to it. Fill it with brake fluid and make sure there are no air bubbles. (video instruction link: https://drive.google.com/file/d/1fd0wdhqxB4nERy6-gydrDsVWCSvOhxRo/view?usp=share_link)

5. Push and pull the fluid through the system. Using both syringes, gently push and pull the fluid through the brake line, alternating between them. You should see air bubbles coming out of either end of the system. Keep doing this until no more bubbles appear and the fluid is clear and consistent.

6. Close the bleed ports and remove the syringes. Start with the lever end and close the bleed port with a cap or screw. Then remove the syringe or funnel and wipe off any excess fluid with a rag. Repeat with the caliper end and remove the syringe and nozzle.

7. Reinstall the brake pads and adjust the lever position. Put back the brake pads into the caliper and remove the bleed block or spacer. Adjust the lever position to your preference and tighten it securely.

8. Test your brakes before riding. Squeeze the lever several times to check if it feels firm and responsive. Spin the wheel and apply the brake to see if it stops smoothly and without noise. If not, you may need to repeat the bleeding process or check for other issues.

Congratulations! You have successfully bled your hydraulic brake on your e-bike. Enjoy your ride!