Shimano HDB Noisy Brakes
Diagnosing and correcting noisy disc brakes
Diagnosing and correcting noisy disc brakes
Diagnosing and Correcting Noisy Brakes
Excessive noise is one of the most common problems associated with disc brakes. It is often seen in conjunction with soft lever
feel and/or a lack of braking power. This guide will focus on diagnosing and correcting brake noise, but it may prove helpful to
consult the other Hydraulic Disc Brake Troubleshooting Guides.
Procedure
The first step is to define the problem. Before beginning any troubleshooting procedures, have a discussion with the rider to
make sure you fully understand the symptoms and their expectations. Next, make sure that the brake system itself is all in
good order, meaning:
• All components (lever, connectors, hose, caliper, pads, and rotors) are compatible with each other, installed properly,
and in good condition – refer to si.shimano.com for individual specifications
• The brake system is compatible with the bicycle frame and wheels
• The brake system is a good match for the rider’s intended usage
• Pads and rotors are not worn past the point of replacement
Problems and Solutions
There are two categories of problems that cause slow lever return or pump up: mechanical and hydraulic. A mechanical
problem is anything outside of the hydraulic system that is acting to restrict movement. These are more common in cases
where the symptom is described as “slow return”. Hydraulic problems occur within the closed hydraulic system and pertain
to the function of the mineral oil. These are more common in cases where the emphasis is on the feel of “pump up”.
Contamination
Brake noise is almost always generated between pad and rotor. Before proceeding any further, verify that the pads have
been properly bedded in. If you are uncertain, repeat the procedure presented in the standalone “Disc Brake Rotor Burn-in
Procedure” guide. A ticking noise indicates a bent rotor, which can be bent back if it is a small bend. Larger bends or warping
require replacement. Squealing or howling comes from a compromised interface between pad and rotor. The two major
culprits of this are heat damage or contamination. If there is significant loss of braking power but the lever feel remains solid,
heat damage is the primary suspect. If there is a significant amount of extra travel or sponginess in the lever, a leak at the
caliper end of the system is a very real possibility. In every case, however, careful inspection of the pads and rotors will reveal
the truth.
Heat Damage
Heat damaged pads take on a “glazed” or shiny appearance, often in an arc that conforms to the braking track. Heat damaged
rotors often show yellow, brown, purple, or blue discoloration. The rotor may also be warped. Heat damaged components
should be replaced, ideally with components better suited to dealing with the heat dissipation demands of the rider.
Excessive noise is one of the most common problems associated with disc brakes. It is often seen in conjunction with soft lever
feel and/or a lack of braking power. This guide will focus on diagnosing and correcting brake noise, but it may prove helpful to
consult the other Hydraulic Disc Brake Troubleshooting Guides.
Procedure
The first step is to define the problem. Before beginning any troubleshooting procedures, have a discussion with the rider to
make sure you fully understand the symptoms and their expectations. Next, make sure that the brake system itself is all in
good order, meaning:
• All components (lever, connectors, hose, caliper, pads, and rotors) are compatible with each other, installed properly,
and in good condition – refer to si.shimano.com for individual specifications
• The brake system is compatible with the bicycle frame and wheels
• The brake system is a good match for the rider’s intended usage
• Pads and rotors are not worn past the point of replacement
Problems and Solutions
There are two categories of problems that cause slow lever return or pump up: mechanical and hydraulic. A mechanical
problem is anything outside of the hydraulic system that is acting to restrict movement. These are more common in cases
where the symptom is described as “slow return”. Hydraulic problems occur within the closed hydraulic system and pertain
to the function of the mineral oil. These are more common in cases where the emphasis is on the feel of “pump up”.
Contamination
Brake noise is almost always generated between pad and rotor. Before proceeding any further, verify that the pads have
been properly bedded in. If you are uncertain, repeat the procedure presented in the standalone “Disc Brake Rotor Burn-in
Procedure” guide. A ticking noise indicates a bent rotor, which can be bent back if it is a small bend. Larger bends or warping
require replacement. Squealing or howling comes from a compromised interface between pad and rotor. The two major
culprits of this are heat damage or contamination. If there is significant loss of braking power but the lever feel remains solid,
heat damage is the primary suspect. If there is a significant amount of extra travel or sponginess in the lever, a leak at the
caliper end of the system is a very real possibility. In every case, however, careful inspection of the pads and rotors will reveal
the truth.
Heat Damage
Heat damaged pads take on a “glazed” or shiny appearance, often in an arc that conforms to the braking track. Heat damaged
rotors often show yellow, brown, purple, or blue discoloration. The rotor may also be warped. Heat damaged components
should be replaced, ideally with components better suited to dealing with the heat dissipation demands of the rider.
