Bike Torque Racing News

Thu, 23 Feb 2023

Brake Noise, What Causes It?

As official Brembo partners our customers regularly get in touch to solve the issue squeaky brakes, so what is the cause?
Typically brake squeal starts after doing some routine maintenance or service work to your brakes, other times it gets progressively worse or it just randomly starts one day.
Most people try to solve the issue by replacing their brake pads. This is the cheapest and easiest part of the braking system to replace so it is the logical first step. If the noise stops, then it is easy to conclude that the pads were the cause of the issue, however this is not always correct.
One of the main characteristics of a friction based braking system is that all the components vibrate together when the brakes are applied. This vibration always creates noise but this is fortunately at a frequency that humans can't hear, or at a low enough volume that it's not noticeable.
Occasionally a brake system will vibrate at a frequency that matches the natural vibration frequency of the brake system, this match in frequencies causes resonance. Resonance is a phenomenom that can considerably amplify noise. The frequency that the brake system is vibrating at will determine whether the noise is a squeal, groan or squeak, however this amplified noise will only be audible to the rider if the vibration frequency is within the range of human hearing.
High quality and well designed braking systems minimise the possibility of resonance, at least when all the components are new. Unfortunately, as bikes start to age and components wear out the vibration characteristics begin to change, this can potentially lead to resonating in the system. This is usually why brakes can start to become noisy after several thousand miles.
As the mileage of the bike increases even further and components start being replaced, the brake system becomes a mix of new and worn parts. This alters the vibration frequencies of each part of the braking system, increasing the chance for resonance and "noisy" brakes after maintenance has been done.
The key thing to note, is that brake noise is caused by a complex interaction between every part of the brake system and not just one component. Every component of the brake system needs to be kept in good condition and be well maintained to ensure the chances of brake noise are kept to a minimum, this also maximises performance and safety. The first place to start when trying to find out what is causing brake noise is to make sure all components are clean and in good condition. Caliper pins and sliders should be greased and pistons should be free. Brake discs should be clean and free of any pitting or corrosion, the thickness must be above minimum, and floating discs should have bobbins that are still within manufacturer specs. Brake pads should be above the wear indicators, free from any contaminants and wearing evenly.

If your brake system is still noisy with all components in seemingly good condition, we would be happy to help recommend appropriate steps to take to solve the issue.