How To Adjust & Maintain Disc Brakes
It is critically important to have a well functioning brake system on your bike. If you feel your brakes are worn or there is an issue, you need to address this. If you are not confident doing the task yourself, it is recommended you take the bike to a mechanic for a service.
How to make your brakes work well
If your bike is new and you are not getting enough ‘bite’ or power in your braking system, it may simply be a matter of the brakes needing to ‘bed in’. This is just a matter of riding the bike for a while and using the brakes. This transfers a thin layer of the braking pad material to the surface of the rotor and aids in performance.
For your brakes to work well, you need:
The wheel to be correctly and firmly clamped in place - check those quick releases or thru-axles.
The caliper needs to be properly aligned and tight.
The rotor needs to be tight and straight.
The pads and rotor must be free from contaminants.
The brakes need to be bedded in properly.
What are the different types of Disc Brakes on Bikes?
You will find either Hydraulic and Cable actuated (aka Mechanical Disc) braking systems.
Hydraulic systems use a sealed brake line from the lever to the caliper. Just like a car.
Mechanicla/Cable actuated systems simply have a cable from the brake lever to the brake calipers that gets pulled to activate the brake. These are a lot easier to work on, relying on standard cables that will be familiar.
Tools for working with brakes
4mm and 5mm Allen keys
T25 Torx wrench/Shimano lockring tool
Clean rags
When working with disc brakes, you should wear a fresh pair of mechanic’s gloves or use a clean rag because the oils in your skin can contaminate the pads and disc brake rotor.
Aligning the calipers
If your calipers need aligning, you should watch our video on how to do this (the task is the same on both Hydraulic and Cable actuated systems): https://youtu.be/2gsS77XdaAI
Step 1 - Tighten the rotor
Check this is torqued correctly onto the hub.
A loose rotor will result in vibration as well as a ‘ting ting’ noise when you ride.
Step 2 - Align and tighten the brake caliper
We want the brake pads to be aligned squarely with the rotor with even gaps on both sides.
Working with Hydraulic systems:
You will see two bolts holding the brake caliper in place. Loosen these a little so the caliper can move.
Squeeze the brake lever and hold.
Now tighten the caliper while still holding the brake lever in.
When you release the brake lever you should find the caliper has self-aligned with the rotor.
Spin the wheel to check your work.
If this is not the case, you will need to again loosen the caliper bolts, and manually align the caliper with your eyes.
As you peer into the caliper, you are aiming for it to be square, with even gaps.
Once happy, ensure all your bolts are tight.
If your brakes are spongy, they may need a bleed. A trip to the bike shop is required here as specialist tools are required. A spongy feel may also indicate your pads are worn out.
Working with Cable-actuated (Mechanical) systems:
Most systems will have a static pad on one side, with a dynamic pad on the other.
To begin, most brake levers will have a little barrel adjuster. Wind this all the way in at the lever. This is for fine adjustment later.
Loosen the bolt holding the cable in place on the caliper.
Loosen the two bolts holding the caliper in place so it can move a little.
Align the caliper so the static pad is close to the rotor but not touching, and square.
Tighten the caliper.
Clamp the cable at the caliper so that the dynamic pad is close to the rotor but not touching.
Firmly tighten the brake cable clamp at the caliper.
Now spin the wheel and pull the brake lever to test your work.
If things are not quite centred, you may need to loosen the caliper bolts and realign the caliper. Spin the wheel to check your progress.
You can add cable tension by turning the barrel adjuster at the caliper and/or lever end.
Once happy, ensure all your bolts are tight.
Bent rotors
If you have setup your brakes and are still getting some rubbing, the rotor may be the issue. The rotors are really skinny and can be easily damaged by putting the bike in the car, or knocking it on something.
A rotor-truing tool can be used to correctly align the rotor. This is really a quick job for your friendly bicycle mechanic as experience is required.
Contaminated pads and rotors
If you have noticed a decline in braking power or your brakes are howling like a banshee, the pads and rotors are likely contaminated.This can happen from picking up oil from the road or having your bike on a bike rack. You also need to be careful with lubricant/degreaser/WD40 and cleaning products. These will certainly contaminate the brakes.
The first step is to meticulously clean the rotors and brake calipers with isopropyl alcohol.
The pads can be removed and top layer sanded if you have enough material left.
Really, the fix is to replace the brake pads with new items and fit them into a clean system. Be sure to then bed them in again.
Worn out pads and rotors
You need to regularly check the condition of your brakes and rotors by looking into the caliper or removing the wheel for a better look.
If you can’t see any material on the pads, it is time for a new pair. Make sure to clean the caliper and rotor really well to prevent any cross contamination. The rotor should be inspected for wear with each set of pads and replaced when worn out