You’re cycling along a quiet country lane enjoying the view and the hum of tyres on tarmac, only for the peace and quiet to be shattered by a loud squealing sound as soon as you pull on the brake levers.
There’s nothing more annoying than squealing brakes. Any unwanted noise from the bike when you’re riding is immensely irritating, but noisy brakes are probably at the top of the list of annoyances.
Why all the noise?
Unfortunately, squealing brakes can be quite common. Besides the annoying noise, squealing brakes can also mean decreased braking performance. Different combinations of braking surface and brake pad can play a part and the conditions can influence the noise your brakes may or may not make.
“Squealing brakes can occur for several reasons, usually, if you have some grease or oil on the brake pad, rotor or wheel rim or the contact between the braking surfaces is misaligned. New brake pads also need to bed-in for optimum performance,” says Shimano.
While contamination is one cause, vibration is another and can indicate poorly set-up brakes. We’ll go through a few of the most common solutions and remedies for eradicating noisy brakes with rim and disc brakes.
The first thing you want to do with rim brakes is to ensure the brake calipers and the braking surfaces of the rim and the brake blocks are thoroughly cleaned and in good working condition. Also, check that all bolts securing the caliper to the frame and the brake blocks to the calipers are securely tightened. Any loose parts can cause unwanted brake noise.
Often the cause of brake squeal is contamination, caused by enthusiastic chain lubing or oil picked up riding on the road in wet conditions with lots of puddles. So make sure the rims are cleaned thoroughly with a degreaser to remove any residue oil. There are many brake cleaners on the market that can help to ensure the braking surfaces are in tip top condition.
The noise might be caused by brake blocks in poor condition, being glazed over or unevenly worn. Pick any small pieces of grit out of the brake blocks and use sandpaper or a file to smooth away the top layer especially if they are glazed over. Are the blocks worn out? Then they need replacing - most brake blocks have wear indicators. If the brake blocks are worn unevenly then that can be a sign they are not set up properly.
As well as inspecting the condition of the brake blocks, also pay attention to the rims. Most aluminium rims have a machined surface that is designed to provide a rough surface to provide good braking performance. A buildup of dirt or a worn rim can be detrimental to braking efficiency, so give them a scrub to remove any residue dirt.
If a good clean doesn’t solve the noise, the other likely cause is vibration caused by a poorly set up brake.
“If your brakes judder and squeal when you apply the brake then there's a good chance your brakes aren't meeting the rim or the rotor correctly. Apply the brake and take a look at how the surfaces come together, then, with the brake still applied, loosen the mounting bolt(s) slightly and, if necessary, reposition the pad or the disc brake mount to ensure an accurate connection point,” says Shimano.
One popular solution is to toe-in the pads. Normally brake blocks are installed so they are parallel with the rims. Toe-in requires setting the blocks so that the front section contacts the rim first. You can buy a special tool to do this, or a piece of cardboard of a few millimetres thickness works well - a folded over business card does the job. Loosen the brake blocks, push the piece of card behind the rear of the block, and tighten the bolt.
Sometimes buying new brake blocks is the best solution, especially if they are badly worn. Rim and brake block combination can be a factor. There are many different brake block compounds available, designed for different rim materials, conditions and demands. Sometimes changing the type of brake blocks can solve the issue of noisy brakes.
Other causes of brake squeal can be due to any play in the braking system or even the hub bearings. A small amount of play in the wheel bearings can also contribute to squealing brakes. Some brake calipers are light and flexy and this can contribute to unwanted play as the brake block contacts the surface of the rim.
The causes of noisy disc brakes are much the same as it is for rim brakes. Again, the most common cause of disc brakes squealing is due to contamination of the rotor or pads. That’s why you have to be very careful when using spray lubricants on a bicycle with disc brakes, probably best to avoid using spray lubes anywhere near a bike with disc brakes.
“Cleaning your rotors or wheel rims regularly with a specific (oil-free) disc brake degreaser is a good way to avoid squealing brakes. Cleaning your pads too can help quieten things down - you can try some sandpaper or grinding the pads - but if the grease has soaked through the pad, you might need to replace them. Don't use a degreaser or chemicals on brake pads, though,” says Shimano.
First, you want to ensure all the braking components and surfaces are spotlessly clean. You can buy dedicated disc brake cleaners and sometimes this can be an instant fix. An alternative and common remedy is isopropyl alcohol. Use it to clean the disc rotors with a small rag. It’s easier to remove the rotor to do this, but you can do it while attached to the wheel.
The disc pads can also become contaminated. Unlike rim brake blocks, it’s not quite as easy to clean pads if they are contaminated, largely because you have to completely remove them from the bike in the first place. Sometimes a bit of scrubbing with sandpaper can remove the top layer of residue and any glazing that has occurred, and this can often work reasonably well, but if it's really bad, you might have to buy new pads. Some people say you can bake brake pads in the oven to cure this problem, but it's not something we've ever tried so can't vouch for its success rate.
The bedding in process with disc brakes is very different to rim brakes and is worth doing properly following installation of new pads. It can make a big difference to the performance. The pads will leave small deposits of material on the disc rotor and the best way to bed in pads is to ride along the street at a decent speed and pull firmly on the brake levers. Repeat this procedure a few time to ensure the discs are adequately bedded in.
The other cause of noise with disc brakes can be down to the caliper not being perfectly lined up with the rotor, or due to a slight bend in the rotor. Disc rotors can bend quite easily, which is why you have to be careful when travelling with the bike in the car or plane for this reason. They can be easily straightened with careful use of an adjustable spanner or a professional tool if you’re feeling flush.
To ensure the rotor is positioned evenly over the rotor, first loosen the two caliper bolts, then while squeezing the brake lever, tighten the bolts. Sometimes this works fine, but sometimes you might need to make some small adjustments by eye - the clearance between the rotor and brake pads is very minimal. You're aiming to have the caliper centrally positioned over the disc rotor with equal clearance either side.
Hopefully, those steps will help alleviate your noisy brakes. Do you have any top tips that you swear by for fixing squealing brakes?
David worked on the road.cc tech team from 2012-2020. Previously he was editor of Bikemagic.com and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds, and you can now find him over on his own YouTube channel David Arthur - Just Ride Bikes.