My brakes feel soft or spongey, what should I do?Updated 14 days ago
How to Bleed Hydraulic Disc Brakes
If your brake levers feel soft or spongy, or if your e-bike is taking longer to come to a complete stop, air may be trapped in your hydraulic lines. Bleeding your brakes removes trapped air bubbles and restores firm, responsive stopping power.
Note: Because hydraulic brake bleeding requires specialized tools and mineral oil, we recommend having a qualified bike mechanic perform this service if you are unfamiliar with the process.
Required Tools & Materials
- Mineral oil brake bleed kit (syringes, tubing, and adapters)
- Brake-compatible mineral oil
- Hex key set (3mm, 4mm, 5mm)
- T15 Torx driver
- Needle-nose pliers
- Flathead screwdriver (or piston spreader tool)
- Isopropyl (rubbing) alcohol & clean shop rags
Step-by-Step Bleeding Instructions
- Power down: Turn off the display and remove the battery. Power cycle the system by holding the power button to discharge any remaining current.
- Secure the bike: Place the bike on a repair stand or elevate it so the wheels can spin freely.
- Remove pads & insert bleed block: Remove the wheel and brake pads to prevent mineral oil contamination. Insert a plastic bleed block between the caliper pistons.
- Prepare the syringes: Fill one syringe halfway with fresh mineral oil and purge any air bubbles. Leave the second syringe empty.
- Attach the bleed kit: Connect the fluid-filled syringe to the caliper bleed port using the appropriate adapter, and attach the empty syringe to the brake lever bleed port.
- Flush the system: Slowly push fluid from the caliper syringe up through the line into the lever syringe. Watch for air bubbles entering the top syringe.
- Cycle the lever: Gently squeeze and release the brake lever a few times while pushing and pulling light pressure on the syringes to free any trapped air bubbles from the master cylinder.
- Seal the system: Once no more air bubbles appear in the fluid, close the caliper bleed screw and remove the syringe. Tighten the caliper port to specification, then disconnect the lever syringe and reinstall the lever bleed screw.
- Clean up: Thoroughly wipe down the caliper and lever using isopropyl alcohol to clean away any spilled mineral oil.
- Reinstall pads & wheel: Remove the bleed block, reinstall your brake pads, and remount the wheel.
- Test: Pump the brake lever several times to set the pad position. The lever should feel firm and engage predictably.
If you have any questions, please reach out to us through our contact form.