Knowing how to adjust bike disc brakes is a useful task that will definitely come in handy if you are a regular cyclist. It is one of those tasks that is simple to learn but requires patience to master. Don’t give up!
Before you attempt to adjust your disc brakes, you will need to ascertain if you have any problems that will stop you achieving perfect adjustment. If you have cable disc brakes, check if the cable moves the caliper arm and allows it to spring back. If not, then you will need to change the cable. We have a great blog post and video on bike brake cable replacement. Now check your static piston. If it doesn’t turn or the hole at the back of it is rounded you may need to fit a new caliper.
If you have a hydraulic disc brake and it feels spongy or you have to pull the lever all the way to the handlebar before it engages you may need to bleed the brakes first.
If the brake is rubbing and slowing the wheel down, it might be that some of the seals in the caliper or lever have expanded or the pistons are too silted up to retract. If this is the case you might need to service your brake or replace it.
Check to see if your rotor is badly bent. If it is, straighten or replace. We have a great video here if you want to know more about rotors.
Check your pads if they are worn or contaminated then replace them. Watch the video here if you need help with this task.
Tools required
Set of Allen keys/Torx™ wrenches– Many parts on the caliper require these tools.
Flat head screwdriver- Required for pushing hydraulic pistons back into place.
How to adjust bike disc brakes that are mechanical
- Put the bike on a stand or turn it upside down.
- Release the cable on the caliper and reset the barrel adjuster(s).
- If you have a grub screw on the static piston then loosen it.
- Unscrew the static piston, just enough to push the left hand side brake pad all the way back.
- Loosen the caliper fixing screws just enough to allow the caliper to move from side to side in the slots.
- Move the caliper so that the right hand brake pad is as close as possible to the rotor without touching it and tighten one of the caliper bolts.
If you position the caliper too far to the left, the caliper lever will not have sufficient movement to push the right hand pad close enough to clamp the rotor.
- Now looking at the position of the pad in relation to the rotor, push the caliper in or out so that the gap between the pad and rotor is even. Because the gap is very small it might be difficult to set it up evenly the first time.
- When you are satisfied, tighten the other bolt.
- Spin the wheel and if the brake is rubbing repeat the process until the rotor no longer catches on that side.
- Now screw in the static caliper so the pad is as close to the rotor as possible without touching it.
- Now it’s time to tighten the cable. Spin the wheel and with one hand push the caliper lever gently until the pads touch the rotor.
- Release slightly, and while still holding it in position, with the other hand pull the cable
and tighten.
- Check the brake and adjust either the static caliper or the cable using the barrel adjuster if required. There might be a tiny rubbing noise and this is acceptable.
- Once set up, if you have a grub screw on the static piston, tighten it.
How to adjust bike disc brakes that are hydraulic
- Put the bike on a stand or turn it upside down.
- Loosen the caliper fixing screws just enough to allow the caliper to move from side to side in the slots.
- Press and hold the brake lever.
- Push the caliper left or right so that the pads sit centrally over the rotor and gently tighten the bolts sequentially.
- Release the lever and spin the wheel to check if the caliper is set to the correct position. There might be a tiny rubbing noise and this is acceptable. If however the pads are still rubbing significantly and slowing the wheel then you might need to do further tuning.
- Loosen the caliper fixing screws just enough to allow the caliper to move from side to side in the slots.
- Now look at the gap in the caliper. By hand move the caliper left and right finding the point where you can see daylight passing through between the pads and the rotor. The gap should be even on both sides.
- While holding the caliper in place use your other hand to gently tighten the bolts sequentially. If you do it too fast the caliper may move.
- Spin the wheel to check if it rubs. If required repeat the process until you’re happy.