How to Align a Hydraulic Disc Brake on a Bike, by Park Tool on YouTube. 5 min 16 s.
- Video length
- 5 min 16 s
- Time to do it
- 20 minutes
- Difficulty
- Easy
- Steps
- 8
What you need
Steps
Put the bike in a repair stand so the rear or front wheel spins freely. Spin the wheel and listen and look for where the rotor rubs the pads.
Check the diagnosis first. A rub can come from a bent rotor, a sticky piston or a misaligned caliper, so confirm the rotor is true before you move the caliper.
Shine a light through the caliper slot so you can see the gap between each pad and the rotor. Note which side is too close.
Loosen the two caliper mounting bolts just enough that the caliper can move side to side. Do not remove them.
Push the caliper so the rotor sits centred in the slot, with equal gaps on both sides. Wiggle it gently until the gaps look even.
Squeeze the brake lever firmly and hold it while you tighten the mounting bolts evenly, a little at a time, alternating between them.
Release the lever and spin the wheel. Listen for rub and check the gaps again with the light.
If it still rubs, loosen the bolts and repeat the centring. Once it runs clean, tighten the bolts to the torque printed on them or in your brake manual.
Tips and common mistakes
Clean the rotor and pads with isopropyl alcohol before aligning so oil and grit do not cause noise.
Tighten the two caliper bolts evenly in small turns so the caliper does not shift as you finish.
If one piston sticks out further, push it back gently with a clean tyre lever before centring the caliper.
Never touch the brake rotor with bare fingers, since oil from your skin can cause squealing.
Questions
Do I need to bleed the brakes to fix a rub?
No. Alignment only needs the caliper bolts loosened and retightened. Bleeding is for a spongy lever or air in the line.
What if the rotor itself is bent?
A wobbling rotor will rub even with a centred caliper. True the rotor with a rotor truing tool or replace it before aligning.
How tight should the caliper bolts be?
Use the torque value printed on the bolts or in your brake manufacturer's manual. Snug by hand is not enough on most brakes.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
