Watch That Manual | How to adjust a disc brake?
11 October 2022
Manuals, you often get them with your new products, but who actually reads them? And even if you do, how much can you still remember of it? Exactly! That's why we make working on your own bike a bit easier, with Watch That Manual! In this series, we show you exactly what to do and what not to do.
Disc brakes are essential for smooth and efficient braking, no matter the weather conditions. With regular maintenance and a few easy adjustments, they will keep performing at their best. In this manual, we’ll cover everything you need to know about adjusting your disc brakes and troubleshooting common problems like rubbing brakes, bent rotors, and loose discs. By the end, you’ll have the confidence to fix these issues on your own.
Problem 1: Rubbing brakes
Rubbing brakes can be annoying but aren’t usually dangerous. This problem often happens after replacing brake pads. Here’s how to fix it:
Start by loosening both caliper bolts that secure the caliper to the frame. You should be able to move the caliper freely. For most of the bikes you need a Torx or Hex key to loosen the caliper bolts.
After loosening you can start aligning the caliper. Use the DiscDoctor tool by placing its metal part over your rotor and aligning it with the caliper. While squeezing the brake lever, hold the caliper in place and tighten both bolts. This aligns the caliper perfectly with the rotor.
Release the brake and remove the metal part of the DiscDoctor. If aligned correctly, your brake should no longer rub against the rotor, and that annoying noise should be gone.
Problem 2: A bend rotor
If your rotor is bent, it may happen after a fall or while transporting your bike. Fortunately, you can fix this issue with the DiscStraight tool.
First things first, never work on a hot rotor. So, make sure that the rotor is cooled off. Now spin your wheel and listen for rubbing sounds to identify where the rotor is bent and on which side. Use the notch on the DiscStraight tool that matches your rotor’s brand and thickness. Gently bend the rotor back with small movements. Don’t apply excessive force, and check your progress frequently to ensure a smooth, freely spinning rotor.
Problem 3: Brake pads too close to the rotor
If your rotor is straight and the caliper is properly aligned but the brakes still rub, the issue may be that the brake pads are too close to the rotor.
To solve this problem first remove the wheel from your bike. Insert the PistonFix tool into the caliper to gently push the brake pistons back into the correct position, you can also use the DiscDoctor tool to do this. Move the PistonFix back and forth until the pistons extend slightly outward. This small adjustment is often enough to fix the issue. Once done, reinstall the wheel and check if the problem is resolved.
Problem 4: A loose disc brake
A loose disc brake is a safety hazard and should be addressed immediately. Disc brakes are mounted in one of two ways: with a six-bolt system or a center lock system.
If your disc is attached with a center lock, you’ll need the same tool that you'll use to remove a cassette (the LockOut tool). Read more about how you replace a cassette in this blog. Place your wheel firmly on the ground and turn the lock ring clockwise to tighten it securely. For six-bolt attachments, use a Torx T key. Tighten the bolts in a star pattern to ensure even pressure. Double-check each bolt to make sure they are securely fastened.
Problem 5: The wheel is not aligned
If your wheel is not aligned properly within the frame, it can cause your brakes to rub, reducing braking performance.
To check if the wheel is aligned you need to set your bike on the ground, open the quick release or remove the thru-axle, and let the wheel settle properly into the frame. Once the wheel is properly positioned, tighten the quick release or thru-axle and check if the rubbing issue is resolved.
Wrap up
Keeping your disc brakes in optimal condition doesn’t have to be difficult. With the right tools and a bit of practice, you can easily adjust and fix common disc brake problems. Now that you’ve learned how to tackle rubbing brakes, bent rotors, and loose discs, you’re all set for a smooth ride.
Remember, your brakes are crucial to your safety, so don’t hesitate to make these adjustments whenever needed.