Bike Not Stopping: No Pressure on Hydraulic Disc Brakes?

Are you finding it challenging to stop your bike? Are your hydraulic disc brakes losing their grip and bite?

In this post, I’ll shed light on why there’s no pressure on hydraulic disc brakes when attempting to stop your bike, and how to fix this issue. 

Disc Brakes with sky in the background
color bike in sunny day, bike series,

Primary Reason for No Pressure on Hydraulic Disc Brakes When Braking

If you’re having a pressure problem with your bike’s braking to the point that you’re not stopping, chances are there’s air in the braking system.

Hydraulic braking systems contain an incompressible fluid that aids in transferring forces. It’s the means of communication between the brake lever and the calipers.

When air—which is compressible—gets into the braking system, the system’s effectiveness gets compromised. This is because the input forces produced when you operate the brake lever are wasted on compressing the air instead of the brake pads.

How to Fix This Issue

The solution to your pressure-related hydraulic braking problem is easier than you might think. All you need to do is bleed your bike’s braking system to eliminate air.

You’ll need an Allen key and bleed kit to bleed your bike’s braking system. Bleed kits vary from one bike brand to another. For e.g If you have a Shimano bike, get a Shimano bleed kit.

Here are the steps you need to follow:

  1. Make sure that both the caliper and lever are as clean as possible.
  2. Use the appropriate Allen key to loosen the brake lever.
  3. Move the brake lever upwards until it’s leveled.
  4. Undo the small Allen key bolt on top of the lever (don’t lose the O-ring).
  5. Screw in the bleed reservoir by hand, and make sure not to over-tighten it.
  6. At the caliper, take off the dust cap.
  7. Grab the bleed syringe and fill it with the mineral oil from the bleed kit.
  8. Attach the bleed syringe where the dust cap was.
  9. Using the appropriate Allen key, undo the caliper’s valve.   
  10. Start pumping the syringe gently (the oil fluid will pop up at the brake lever’s reservoir).
  11. As you’re pumping the syringe, flick the brake cable to eliminate air bubbles.
  12. Once the brake lever’s reservoir is full, seal the caliper’s valve.
  13. Use the bung in the bleed kit to plug the hole at the reservoir.
  14. Unscrew the reservoir, dispose of the old fluid, then put the lever’s bolt back in place.  
  15. Remove the bleed syringe’s hose from the caliper, then put the dust cap back in place.

Note that you need to repeat the above-listed steps for the other brake. Also, always ensure the bleed point is the lowest area of the braking system.

Why do bike disc brakes rust

Other Breaking Issues for Bikes With Disc Brakes

There are a couple of other issues that might be hindering your bike’s hydraulic braking system:

Brakes Are Soft When Braking

If the brake lever feels soft or spongy, you’re dealing with partial pressure loss. This is also caused by the presence of air in the system.

All you have to do to fix this problem is follow-above-listed bleeding steps.

Pistons Relocate Due to Heavy Use Causing Pad Drag

If you pull the brake lever and it engages normally, yet your bike isn’t stopping, you’re looking at a friction issue here, not a pressure issue.

In this case, you need to inspect the caliper. Pull the pad and take a look at the pad face. If you notice that it’s glazed or shiny, then you know that it isn’t providing enough friction.

To deal with this issue, you’ll need some drywall sanding screen, which you can get from any hardware store. Place the pad’s face onto the sanding screen, then start rubbing it in a figure-8 or circular motion to restore pad friction.


How to Tighten Hydraulic Disc Brakes?

  1. Make sure the bike is in an elevated stance.
  2. Use a hex wrench to loosen the mounting bolts outside the brakes.
  3. Pull the brake lever to center the calipers.
  4. If the calipers aren’t aligned properly, try rotating the centering bolts.
  5. Release the brake lever and check for rubbing by spinning the wheel.
  6. Tighten the mounting bolts securely.

Click here to learn how to adjust other types of brakes. 

Wrapping Up

There you have it; now you know the reason behind the pressure issue in your hydraulic braking system. Simply follow the above-listed steps to bleed the braking system so that it regains its effectiveness.

Good luck!