How To Bleed Mountain Bike Brakes?

How To Bleed Mountain Bike Brakes? – [7 Easy Steps Guide]

Recently I was generating air bubbles in the break bubbles.

I got a little confused;

But, thanks to senior, after discussing it with a senior, I got to know that;

Your mountain bike’s hydraulic disc brakes are fantastic at generating stopping force, but they need periodic maintenance to maintain good working order.

Bleeding your bicycle’s brakes reduces air bubbles in the brake lines, ensuring that your brakes feel and function properly. So how can you bleed the mountain bike brakes?

Your MTB bike’s brakes may feel spongy at the lever, which is often a sign that the system has absorbed some air.

While bleeding your MTB bike’s disc brakes isn’t something that should be done as part of normal maintenance, it’s still a simple process that shouldn’t put you off.

Here is a summary of the information for your convenience.

How to Bleed Mountain Bike Brakes?

Tools Required To Bleed Disc Brakes:

To bleed disc brakes, you will need the following:

  • A bleed kit specific to your brake system
  • A clean, clear container to catch the old brake fluid
  • Hydraulic Mineral Oil
  • Isopropyl Alcohol
  • Bleed Funnel
  • 5 mm Wrench
  • 3 mm to 7mm Wrench or Pliers, depending on brake style.
  • Bleed Block
  • A small wrench or Allen key to loosen the bleed valve
  • A friend or a brake bleed tool to help you pump the brake lever or pedal.

Steps to bleed mountain bike brakes:

putting oil in brake

Step 1:

  • Before anything else, you should remove the pads and replace the pistons in the caliper.
  • Place the bicycle on a work stand, then remove one of the wheels. Put a screwdriver with a flat blade or a piston press between the disc brake pads, and then use the tool to force the pistons back into their bores.
  • First, remove the pin holding the pads in place, then remove the pads from the caliper. Put in a block for the bleeding.

Step 2:

  • Thread the bleed cup in a careful manner. Use a 4mm wrench to loosen the brake lever bar clamp. To make the lever horizontal with the ground, rotate it anticlockwise and tighten it.
  • First, remove the little o-ring from the lever’s reservoir using a pick, and then use a 2.5mm key to take out the screw that secures the bleed port on the top of the reservoir. There are occasions in which this will emerge together with the cap.
  • Insert the bleed cup into the bleed port by turning it clockwise. It is quite simple to strip the threads on the cup if you overtighten this, so take care not to do so.

Step 3:

  • Turn the bleed valve or nipple anticlockwise and depress the bleed hose button.
  • Remove the dust cover from the bleed nipple on the caliper. Fill the bleed syringe with mineral oil and connect a bleed hose to the bleed syringe. Flip the syringe over and use the other end to remove air bubbles.
  • Place a ring spanner with a 7mm opening over the bleed nipple, and then connect the other end of the hose to the bleed nipple. Instead of inserting a key of that size into the bleed valve, non-series brakes need a 3mm key.

Step 4:

  • Using a syringe, inject fluid into the system at the appropriate locations.
  • Release the parking brake and turn the spanner or key a quarter turn anticlockwise.
  • Insert the syringe into the system so that oil is forced through it. To prevent air from entering the caliper, you must stop the process and seal the valve and nipple.

Step 5:

  • Use a zip tie to secure a bag to the conclusion of the hose.
  • Take the syringe off the end of the hose and set it aside.
  • Place the hose into the bag with the end facing downward. You may use a zip tie to attach the bag, but you have to be careful that it doesn’t squeeze the hose wholly shut.
  • Open the bleed valve/nipple.
  • Continue pumping until about half of the fluid is removed.

Close the bleed cup after you’ve drained off about half of the oil inside it. After pumping the brake lever a few times, opening the valve or nipple, squeezing it to the bar, and then closing it, you may let go of the lever. It should be done four times.

Step 6:

  • Put the valve or nipple in its closed position and remove the bleed hose. Tap all down the brake line length to dislodge any air bubbles that may have formed. Try applying and letting go of the brake lever many times.
  • Repeat the process with the brake lever angled forwards by 30 degrees and then backward by the same amount. Bring the lever back to its horizontal position.

Step 7:

  • Install the plastic plug that comes with the bleed cup, then remove the cup entirely.
  • Replace the lid for the bleed port. When you reinstall the screw that controls the bleed port and the o-ring, be careful not to overtighten the screw.
  • Take off the bleed block and use a paper towel to wipe the inside of the brake caliper. Replace the brake pads, then reattach the wheel. Check the stability of the brake lever by pumping it.

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Things to Keep in Mind While Bleeding the Brakes on Your Mountain Bike

Bleed Mountain Bike Brake

After using brakes from a variety of manufacturers for several years, I’ve picked up a few pointers on the finer points of bleeding and setting everything up, which are as follows:

  1. When bleeding, it is very necessary to position the bleed port on your lever so that it is at the highest possible point while positioning the port on your caliper so that it is at the lowest possible place in the system. If this is not done, bubbles will get caught in the line.
  2. It is helpful to insert a bleed cup or syringe into the lever, pull the lever, strap it to your handlebars, and let it rest for thirty to forty minutes before removing it. As a result, bubbles will be able to float into the cup, significantly stiffening up the lever’s sensation while you ride.
  3. Before installing new pads in a system that has just had a bleed, moisten the newly exposed surface of the new pads with water and rub them against one another to remove the top layer. It will ensure that the new pads have a good, strong bite.
  4. Because not all fluids are the same, you must be selective about the mineral oil or DOT fluid you put into your braking system. Under NO circumstances should you combine the two types of fluids

When do the disc brakes on a mountain bike need to be fixed up?

If the ability of the bicycle’s brakes to stop the vehicle suddenly becomes less effective, you must investigate the root of the problem immediately.

Because brakes are such important components to a bicycle’s overall safety, they must constantly be in good working order.

In most cases, three factors contribute to a decline in the braking power of hydraulic disc brakes:

  • The brake pads have reached the end of their useful life; in this scenario, you should change them.
  • The brake pads and discs need to be cleaned: A guide here will show you how to clean your brakes.
  • The pressure point shifts, and there is air in the braking system; this occurs because, In this particular circumstance, you need to bleed your brakes.

If the pressure point drifts or becomes spongy, it is generally recommended that the brakes be bled. If the brake fluid has been used for a significant time, it should be replaced completely.

Bleed Mountain Bike Brakes

Regardless of how well the braking system is performing, we strongly advise having it inspected at least once yearly. It is something that may be done as part of a spring check.


Your mountain bike is equipped with hydraulic disc brakes, which are fantastic for delivering stopping force. However, to maintain them in good working order, they do need some periodic maintenance.

When you bleed the brakes on your bike, you eliminate any air bubbles trapped in the brake lines. It helps your brakes continue to feel firm and perform effectively.

Most mountain bike manufacturers have made it quite simple to bleed their disc brakes by providing riders with the appropriate equipment and components.

To make your brakes feel as good as new, you will need to get a bleed kit and follow the instructions outlined above.

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