How To Adjust Bike Disc Brakes: Hydraulic and Mechanical [With Video Guide]

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If you look after your bike, it will look after you. This is what a very experienced cyclist said to me when I first started riding, and I couldn’t agree more after decades on the bike. 

With their increasing popularity, it’s more important than ever to learn how to adjust bike disc brakes – both hydraulic and mechanical.

When it comes to adjusting bike disc brakes, they can be challenging. They come in all different shapes and sizes and adjust in different ways.

It’s easy to get wrong, but as long as you have some friendly advice to show you how to adjust disc brakes on a bike, it’s actually very straightforward.

In this article, we’ll be walking you through:

  • What Are Disc Brakes?
  • What Are The Benefits Of Learning How To Adjust Bike Disc Brakes?
  • How To Adjust Mechanical Bike Disc Brakes in 4 Steps
  • How To Adjust Hydraulic Bike Disc Brakes in 5 Steps
  • Robbie’s Video Maintenance Guide: How To Adjust Bike Disc Brakes

Let’s dive into how to adjust bicycle disc brakes!

How To Adjust Bike Disc Brakes: Title Image

What Are Disc Brakes?

Over the past decade, disc brakes have become the new standard, with rim brakes slowly becoming less common on newer bikes.

Disc brakes are incredibly powerful, work well in all weather conditions, and are excellent on muddy trails. 

Instead of gripping a braking surface on the bike’s rim (as rim brakes do), they feature calipers that clamp onto a braking surface (the brake rotor) attached to the center of the wheel.

A mechanical disc brake on a mountain bike suspension fork.
Mechanical disc brakes

Disc Brakes: Mechanical or Hydraulic?

Disc brakes come in two types: mechanical and hydraulic.

Mechanical disc brakes use a cable like a traditional rim brake. When the cable is pulled by the lever, it pulls the pads together, gripping the disc and creating friction.

Hydraulic disc brakes don’t use a cable; they use brake fluid.


When you pull the lever, it compresses the fluid, which pushes pistons into brake pads gripping the disc. Hydraulic disc brakes are generally seen as superior, as they provide more powerful braking and greater control (“modulation”) over the brake application.

Most hydraulic disc brakes are self-adjusting and require bleeding when being installed.

In this article, we will be telling you how to adjust both types of disc brakes, starting with how to adjust mechanical disc brakes.

A Shimano GRX hydraulic disc brake on a Lynskey carbon gravel fork.
Hydraulic disc brakes

What Are The Benefits Of Learning How To Adjust Bike Disc Brakes?

Learning how to adjust disc brakes is an essential skill for many cyclists to learn. It comes with a huge amount of benefits:

Better Braking Power

You will get much better braking power if your brakes are properly adjusted.

It means the pads connect to the discs properly, and you can create more friction, allowing you to stop quickly. 

Better Modulation

Properly adjusted disc brakes give you much better modulation.

This means you have a much better ability to feather the brakes and get the perfect amount of power to avoid locking the wheel and still stop quickly. 

Even Brake Wear

When disc brakes are properly adjusted, they wear evenly. This not only helps with braking power but should also mean that your pads last longer.

No Disc Brake Rub 

You will get disc brake rub if your brakes are not properly adjusted.

This is where the disc slightly catches the pads every rotation even when the brakes aren’t being applied. Not only will this slow you down, making you feel like you’re constantly pedaling uphill, but it can also be very annoying to listen to when riding.

How To Adjust Mechanical Bike Disc Brakes in 4 Steps

Mechanical disc brakes are easier to adjust, but require more regular maintenance.

You will only require the following:

  • Allen Keys (Hex Keys)
  • Bike Stand (optional)

Step #1. Check Components

First, you must check the components to ensure everything is working properly and nothing is too far-worn.

We do this because we might not be able to properly adjust the brakes if they don’t work as they should. Here’s what you need to check.

  • Cables: Check the inners and outers work smoothly and don’t get stuck.
  • Calipers: Check the calipers are working properly and functioning as they should.
  • Pads: Check the pads to ensure they have compound left on them.
  • Discs: You should have 1.5 mm as a minimum left on the disc.
  • Levers: Check they are not broken, and they return properly after being pulled.
  • Contamination: Ensure there’s no oil on the disc brakes or pads.

If you find anything that needs replacing, it’s best to do it now before getting into the task at hand.

Step #2. Correct Tension

Releasing the tension from a cable pinch bolt on a mechanical disc brake.

Next, take the Allen key and go to the cable pinch bolt. Undo it anticlockwise, and the cable should come free. After it’s free, screw in any adjusters so you’ve got room to work with later.

Pull the cable finger-tight with one hand, and with the other, tighten the pinch bolt up. Now pull the brake lever to ensure when pulled, the caliper reacts.

Now, use the adjuster to get the tension perfect. You are looking to get the perfect amount of leverage so it’s not too tight but also not too loose that it hits the handlebars.

Don’t worry if it rubs when the disc rotates; we’ll fix that next.

Step #3. Realign The Caliper

Aligning the caliper on a mechanical disc brake.

Next, we need to realign the caliper.

You will need to go to the two bolts which mount the caliper and slightly undo them, but only a small amount until they can be moved under pressure. 

Then, grip the brake lever so the pads clamp onto the disc. Hold this pressure on the lever and then tighten up the bolts on the caliper. Once tight, you can release the brake lever.

Step #4. Test

Finally, you are going to need to test that your adjustments worked!

First, just spin the wheel in the stand and listen for brake rub. If there is any, realign the caliper again.

If you don’t get any brake rub, pop the bike out of the stand, go somewhere safe, and test the brakes work while riding. If they’re not quite right, head to the adjuster, and fine-tune it.

How To Adjust Hydraulic Bike Disc Brakes in 5 Steps

An Allen key set next to a tire lever on a workshop floor.

Next, we will be adjusting hydraulic bike brakes.

Hydraulic disc brakes generally don’t need much maintenance, as most are self-adjusting. However, things can go wrong from time to time.

Here’s what you’ll need when learning how to adjust hydraulic bike brakes:

  • Allen Keys
  • Tire Lever
  • Bike Stand (Optional)

Step #1. Check Components

A hydraulic disc brake caliper. Shimano GRX.

As we did with mechanical disc brakes, we need to check the components before adjusting the hydraulic bike brakes themselves.

  • Cables: Check for any leaks or wear.
  • Calipers: Check the calipers are not damaged.
  • Pads: Check the pads to ensure they have compound left on them.
  • Discs: You should have 1.5 mm as a minimum left on the disc.
  • Levers: Check they are not broken and don’t feel spongy.
  • Contamination: Ensure there’s no oil on the disc brakes or pads.

If you find anything that needs replacing, it’s best to do it now. You will need to get the brakes bled if you find any fluid leaks, or if the levers feel spongy. 

Step #2. Remove the Wheels And Pads

Next, remove the bike’s wheels, taking care not to bend the brake rotors. 

After the wheel is out, ensure you don’t touch the brake lever, as this will adjust the pistons further inwards.

Now, you will need to take the brake pads off. Take the clip off the security bolt, then use the Allen key.

Undo the pin and pull it from the brakes, then pull the pads out, remembering which pad went on which side. 

Step #3. Reset The Pistons

Resetting the pistons on a Shimano GRX hydraulic disc brake caliper.

Next, we need to reset the pistons.

For this, you’ll use your tire lever – or you can use anything blunt to push them apart. You do this by putting it into the center of the caliper where the pads sit and pushing them back. 

Take great care not to pierce the piston in the process, as this will mean you will have to replace the caliper, which could be expensive. 

Now it’s time to put the pads back in, ensuring the pads go back correctly as they came out and the pin and safety clip is back in, before refitting the wheel.

Step #4. Align The Caliper

Aligning the caliper on a Shimano GRX hydraulic disc brake caliper.

Next, we are going to align the caliper.

Slightly loosen the bolts on the caliper so it can move under pressure, but not so much that they are hanging loose. It’s normally as little as half a turn.

Pump the brake lever twice. The second time, hold the lever in, and use the Allen key to tighten the caliper back up again. The caliper should now be aligned enabling you to spin the wheel with no disc brake rub.

If it isn’t, we recommend loosening one bolt and fine-tuning it, just moving it a millimeter at a time. It might take a little patience to get it perfect, depending on the brakes you have.

Step #5. Test

Finally, you are ready to test your adjustments!

Drop the bike out of the stand and then go somewhere safe to give it a good test. You should get excellent braking power and no disc brake rub.

If you’d like to know more about adjusting other types, check out our Ultimate Guide To Adjusting Bike Brakes: The 4 Key Types here!

Robbie’s Video Maintenance Guide: How To Adjust Bike Disc Brakes

Check out the BikeTips YouTube Channel here for walk-through bike maintenance guides and more!

Found this Bike disc brake adjustment guide helpful? Check out more from the BikeTips

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Robbie has traveled the globe as an endurance athlete and bikepacker, breaking world records and competing in international ultra-cycling events such as the BikingMan series and the Transcontinental Race. He's also worked as an ambassador for some of the industry's leading names, including Shimano and Ritchey. If Robbie's not on a bike, he's either fixing them or out walking with his dog!

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