Disc Brakes 101: Proper Adjustment for Smooth Riding, by GCN Tech on YouTube. 6 min 47 s.
- Video length
- 6 min 47 s
- Time to do it
- 30 minutes
- Difficulty
- Medium
- Steps
- 9
What you need
Steps
Put the bike in a stand so the rear or front wheel spins freely. Spin the wheel and listen for the rub to find where the rotor touches the pads.
Check the quick fixes first. Make sure the wheel is seated fully in the dropouts and the thru axle or quick release is tight.
Look down through the calliper slot. If the rotor sits off centre, loosen the two calliper mounting bolts slightly, squeeze the brake lever to centre the pads, then tighten the bolts.
Spin the wheel again. If it still rubs, check the rotor for bends by eye and straighten any wobble with a rotor truing tool or an adjustable spanner.
Remove the wheel and take off the brake pads. Clean the calliper pistons and body with a rag and isopropyl alcohol or brake cleaner.
Push the pistons back into the calliper with a clean tyre lever or plastic piston tool. Refit the pads and wheel, then pump the lever a few times to reset pad contact.
If the rub persists, the frame or fork mount may not be square. Use a disc brake mount facing set to cut the mount faces flat and parallel.
Refit the calliper with the facing tool removed. Tighten the mounting bolts to the frame maker's torque spec, usually printed near the mount.
Spin the wheel one last time. Adjust pad clearance with the calliper's barrel adjuster if the lever feels soft, then test the brake at low speed.
Tips and common mistakes
Never touch the rotor surface with bare fingers, since oil causes squealing and weak braking.
Clean the calliper outdoors or over a tray, as brake cleaner and old fluid are harmful to skin and paint.
Facing the mount removes metal, so only do it if centring and cleaning have failed.
Check pad wear before adjusting, because worn pads can make the rotor rub even when the calliper is centred.
Questions
Do I need the mount facing set for a rubbing brake?
No. Most rubbing is fixed by centring the calliper, truing the rotor or cleaning the pistons. Facing is a last resort for frames with uneven mounts.
How do I know if the rotor is bent?
Spin the wheel slowly and watch the gap at the calliper. A bent rotor will swing toward one pad at the same point each turn.
Can I ride with a slightly rubbing brake?
Short rides are fine, but constant rub wears pads and rotors and can damage the frame over time. Fix it soon.
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.
