How to Adjust Hydraulic Disc Brakes on a Bike

The hydraulic disc brakes come with a wide range of advantages when compared with the other types of the brake. The biggest advantage of such brake is they allow you to brake quickly without a lot of finger efforts. Another significant advantage of such brake is they offer you a long-term performance when compared with other types of bike brakes.

To get the best performance from a hydraulic brake, you will need to adjust the brake correctly. If you don’t know how to adjust hydraulic disc brakes on a bike, then keep reading this article.

Adjusting a hydraulic brake is pretty straightforward. You can complete the whole procedure within a moment. In below, we will provide you step by step guide of adjusting a hydraulic brake on a mountain bike quickly.

Different Terms about Hydraulic Brake

Before we begin, you will require to know about some of the hydraulic brake terms. Knowing about these terms will help you to make the procedure easier for you.

Reach adjust

Reach is the adjustment between the brake lever and handlebar. You can adjust the reach with either a finger screw or 2mm bolt. As the different bike comes with different types of handlebar and brake lever mechanism, we will recommend you to check your brake manufacturer manual guideline or website to find out the efficient way.

Free Stroke

That is another adjustment which ensures the duration you will need to pull the brake before the pads hit make contact with the rotor.


Modulation means the amount of the stroke that the brake has from its initial engagement to fully locking up. Low modulation means the brake will require only a little engagement before it locking up. Besides, high modulation implies the lever can be manipulated for a bigger range before the brake lock up, and the wheel stops.

Brake Calipers

The brake calipers are the part of the bike which squeezes the brake pads against the surface of the rotor to stop or slow the bike. When accurately attached, the calipers will only work when you turn the brake levers.


The piston is another part of the brake, which is also known as the plunger. It is either makes of metal or ceramic, or composite cylinders. The piston is another integral part of the disc brake. The primary function of the component is to control the fluid pressure by pushing and pulling which in return turn the rotor of the brake.

Brake Pad

The brake pad is the main component behind the mechanism of the hydraulic disc brake. It interacts directly with the rotor and brakes or slows down the bike. There can be different types of brake pad, including metallic, resin, or metal sintered. Different types of brake pad perform better in different weather condition.

As an example, the metal sintered or metallic brake pad can perform very well in the wet weather. You can get a consistent performance from such brake pads in the wet condition. Moreover, as made of metals, they are highly durable and last longer than the other varieties of the brake pad. However, one big drawback of such pads is they wear out the rotor of the brake faster. Sometimes they also produce rattling noise which may disturb the rider.

The resin pads are usually a better choice for dry weather. They work smoothly and don’t produce any noises while working. Moreover, they don’t wear out the rotor quickly as like as the metallic pads. However, the drawback of such pads is they don’t last long as like as the metallic pads.

One exciting thing you can do is installing the both of the brake pads on the brake of your bike. You can use them depending on your condition.

Dot Fluid and Mineral Oil

We all know that the hydraulic disc brakes are controlled using fluids. The fluid helps to transfer pressure from the lever of the brake to the caliper. The DOT fluid and the mineral fluid are two types of fluid that are used in almost all the modern hydraulic braking mechanism.

Olive and Barb

These two parts of the braking mechanism connect the hose with the lever. Generally, the barb is equipped in the starting point of the brake hose at the lever. Barb ensure the correct amount of fluid is transferring after the lever is being pressed. On the other hand, the barb is a small metal piece which is inserted between the lever and the hose with a hollow bolt. The barb is used to entire seal one end of the brake. 


The rotor is also known as the disc, and you probably know what it is. If not then the rotor is the circular metal plate equipped in the hub which grabs the brake to slow down the bike.


The bleed is a point which is used to add or remove the fluid. From this point, you can remove the air, dirt, or water which entered in the system while biking. However, the part is mainly used for replacing the fluid.

How Hydraulic Disc Brake Works?

The hydraulic disc brake mechanism is not that complex as most of the people think it is. The hydraulic brake includes two brake pads which apply pressure to the rotor. The pressure is produced by the levers which move the compressed fluid and finally, presses the disc brake pads and slow down the bike.

How to Adjust the Hydraulic Disc Brake

Okay, let’s come to the main point of the article. Start with positioning the bike in the bike stand. Now check the brake lever=. The brake lever should be horizontal when compared with the handlebar. As there are possibilities of tweaking the lever in a crash, you should rotate it down, so it doesn’t stay level with the handlebar. The best position of the lever is just below the handlebar. You can do this by loosening the nuts of the brake lever using a hex wrench. Then position the lever in the proper place and tighten the nuts. You are done. 

Now it is the time to adjust the brake calipers. It is essential to keep the brake caliper in align so that they don’t crash with the spinning rotor. If the caliper is not aligned correctly, you may hear a disturbing rubbing sound too.

For doing so, spin the bike wheels and notice how the rotor is moving in between the calipers. The rotor should be centered. If you hear any rubbing sound, then loosen the two centering bolt with a hex wrench. No turn the brake lever gradually and tighten the center bolts. Now spin the wheel again and check whether it is rubbing or not.

Finally, take the bike for a test ride. Now check the brake for multiple times then check the brake and the lever. The lever of the brake should be in a comfortable position, and the rotor should not be rubbing. And of course, the brake should be accurate.

Hydraulic Disc Brakes Tips

Here are some tips about hydraulic brake that may be helpful for you.

  • If the brake produces a metallic sound, then it may be caused by the worn-out brake pads. In such situations, you will need to replace the brake pad. There is an easy way to detect whether the pad requires replacing or not. Measure the pad with a scale. If less than 3 mm of the pad is remaining, then the pad needs replacing.
  • If you feel the brake is spongy and don’t pull properly then maybe it is caused by the air in the mechanism. In such situations, you may need to bleed to make the air out. Also, check the pad to ensure if they require replacing or not.
  • If you feel that the brake is gradually becoming weaker, then it may be caused by dirt inside the system and rotor or worn pads. Clean the rotor, as well as the braking pad, and other parts of the brake.


As we say, adjusting hydraulic brake is not that. That should be much easier for you after reading the entire article. The hydraulic brake is a good investment, and it requires a notable amount of money to replace the brake. So, you should take proper care of the bicycle brake to get a long-term performance from it.

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