How To Stop Hydraulic Disc Brakes From Rubbing

It can be frustrating riding a bike with hydraulic disc brakes that keep rubbing. The disc brakes will produce unnecessary noise making your bike look uncared for. It will also make your brake pads and rotor not last long as they’ll wear within no time.

 Hydraulic Disc Brakes

What makes a hydraulic disc brake keep rubbing is a wrong caliper alignment or bent rotor. To stop the rubbing, you need to realign the caliper and rotor. Do you know how to do this? 

This guide will show you a step-by-step process to help you prevent your disc brake from rubbing.

What Causes the Hydraulic Disc Brake Rub?

Several reasons can make your hydraulic disc brake keep rubbing. It could be burrs, damages or dirt that collects on the piston, making it sticky. It would be hard to set the brakes up when the disc brake has these problems, frustrating your efforts and wasting time. 

It also could be that the wheel isn’t seated well between the fork and frame. Another reason can be a bent rotor which makes it hard for the bike to stop moving.

How Hydraulic Disc Brakes Works

If you want to fix this problem, it’s best to know where the noise comes from and what makes it rub. Remember, a hydraulic disc brake sits on the handlebars of your bike and has a reservoir containing brake fluid. The brake fluid travels through the brake lines, but the fluid moves to the caliper when you use the lever.

The caliper contains brake pads and a piston. When using your hydraulic brakes, the brake fluid will push the pistons, forcing the brake pads to come together. When the pads come together, they will squeeze the rotor enabling you to stop the bike from moving.

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How To Fix The Rubbing Hydraulic Disc Brake Problems

After understanding how hydraulic disc brakes work, you can go ahead and determine the cause of the noise. To get to the root cause, try rotating your bike’s wheel and then checking the space between the pad and rotor on the brake caliper.

If you notice that the rotor keeps rubbing, you should realign the caliper to stop the noise. However, if it’s the disk that’s bent or wobbles as the wheel spins, you’ve got to straighten it.

1. Realign The Caliper To Stop The Rubbing

One of the best ways to stop your hydraulic disc brakes from rubbing is to realign the caliper. You can do that by;

  • Loosen the two bolts holding the caliper in place.
  • Then pull the brake lever. After that, the caliper will move to the center.
  • After that, retighten the mounting bolts. Ensure the other hand holds the lever tightly to have it in place when doing this.
  • Test if the disc brake still rubs by spinning the wheel. 
  • If it doesn’t, consider loosening the mounting bolts further.

Realign The Caliper To Stop The Rubbing

Alternatively, you can opt for loosening a bolt at a time to avoid doing too much work. Keep spinning the wheel to help you re-adjust the caliper when doing this. Try pushing the caliper in the direction you feel will stop the rubbing. Then retighten the bolt.

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Use A Paper

Another better way to stop the rubbing is using paper. Cut a small piece of paper and fold it longways. Then remove the caliper and place the piece of paper on the brake rotor. After that, put the caliper in the right position on top of the paper. Then pull and hold the brake lever, tighten the bolts, and test if the rubbing is over. Ensure you remove the paper before you spin the wheel for a test.

However, if after you do all these and the disc brake still rubs, the problem is not on the caliper. You can consider tightening the mounting bolts on the rotor and test if there’s further rubbing. Remember, if the rotor is loose, it will also cause an annoying noise.

2. Straighten The Rotor

If you realize the problem is on the rotor after trying to re-adjust the caliper, it’s best to straighten it. Remember, the disc rotor should stay vertically to work best. However, there are instances when it can recline horizontally, making it rub the disc. This can happen when it crashes or has dirt build-up.

Straighten The Rotor- Hydraulic disc brakes

You should use a rotor truing tool or an adjustable spanner to rectify this. Alternatively, you can straighten the rotor with your hands by carefully squeezing it. When doing this, ensure your hands or tools are clean.

Identify where the rotor rubs and decide where you need to place it to stop it from contamination. After identifying the right place, gently move the rotor in that direction. Do this until the rotor stops rubbing. However, you shouldn’t bend the rotor too far in the opposite direction, bringing in more complications.

Note that after straightening the rotor and it keeps rubbing, the best solution is to replace it.

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3. Clean The Caliper Pistons

When the brakes are dirty, the calipers will get stuck, preventing them from working. It won’t be able to retract after you release the brake lever making the brake pads rub on the disc. You should, in this case, clean the brake caliper piston.

Clean The Caliper Pistons

You can do that by;

  • Detach the bike’s wheel and brake pads and put them in a safer place to prevent them from getting contaminated.
  • Then pull the brake lever to enable you to remove the pistons out. Ensure you carefully handle the piston since the brake fluid will spill if they come out. Also, if you let the pistons pop out, they will give you challenges returning them. Pop the piston half the width of the calipers.
  • After that, use an old toothbrush and brake cleaner to clean it.
  • Gently rub the calipers as you clean, and avoid pressing them too hard as this will damage them.
  • Also, clean the sides of the piston. But avoid cleaning the front part.
  • Then use a microfiber cloth or paper towel to wipe off any remaining dirt.
  • Smear some brake fluid on the sides of the piston.
  • You should then clean the other side of the piston. If the calipers have more than one piston, clean both. But do clean one at a time.
  • Then return them to the right place.

Note that if the rubbing doesn’t stop, the problem could be damaged O-ring seals around the pistons. It could also be a faulty brake cylinder on the brake lever. You should, in this case, consider replacing the cylinder or the calipers.

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4. Install The Wheels Properly

Sometimes this may not be a serious problem requiring an expert to diagnose. Instead, look at the bike’s wheels to see if they’re properly installed in the frame and fork.

Install The Wheels Properly Hydraulic disc brakes

You can rectify this by removing the wheel and re-installing it well. Untighten the quick release lever, then apply enough pressure downwards to help put the frame and axle in place. Then tighten back the quick-release lever.

5. Replace The Brake Pads

Brake pads should serve you for some time, depending on what they’re made of. Your bike brake pads can also take fewer days to wear off if you’re an aggressive rider, the way you use them, and the conditions you ride in.

Replace The Brake Pads - Hydraulic disc brakes

If your brake pads get damaged before a year, you should make plans to replace them to prevent rubbing when they wear out. However, it’s advisable to have a spare brake pad if yours wears faster to avoid inconveniences.

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6. Inspect If There’s a Leakage on The Hydraulic Hoses

Bikes with hydraulic disc brakes have hydraulic hoses which can leak at times. It can be hard to notice the leak, but it will attract dirt to the area resulting in noise or rubbing. You should take your bicycle to a bike shop for repairs if you spot the leak.

Inspect If There's a Leakage on The Hydraulic Hoses - Hydraulic disc brakes

7. Avoid Hard and Continuous Braking

Are your rubbing hydraulic disc brakes on a new bike? If you’re using a newer bike, it’s normal for the hydraulic disc brakes to rub when cornering or cycling out of the saddle. It can also make a noise if you’re carrying a heavy load which doesn’t mean the brake disc has a problem.

If the rubbing isn’t too much, you have no cause for worry as the bike will adapt to the new changes. Allow the brake pads and the disc to get used to working together, as they will stop rubbing with time. This noise can result from a small clearance between the disc and brake pads, so the rubbing will cease with time.

However, if you want to stop this, refrain from hard braking. Instead, brake gently and not continuously on long descents. The rubbing will stop after covering about 300km after the brakes are fully ridden in.

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Bottom Line about Hydraulic disc brakes

It’s normal to experience a rubbing brake as you cycle. Despite the noise from the rubbing being annoying, it can sometimes affect your speed. This is a common problem with new bikes and hydraulic disc brakes. Some causes you can fix by yourself, while others require you to take your bike to a bike shop for professional handling. For example, you can realign the caliper or the rotor. But when there’s a leakage, you should take it to an expert.

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