If you’re riding among other cyclists or in the middle of a town, squeaky bike brakes can be both irritating and embarrassing.
Squeaky bike brakes are more than just an annoyance. They can indicate a potentially dangerous or expensive problem with set-up or their condition.
What Causes Squeaky Bicycle Brakes?
Whether your bike has disc brakes or rim brakes, the causes of squeaking are often broadly the same.
Whether it’s the brake shoe of a rim brake or the brake pad of disc-brake, contaminants like grease, oils, sand, dirt and grit can impair braking efficiency. All braking surfaces must be clean to avoid inefficient and noisy braking.
Because brake pads or shoes are porous, you won’t always be able to easily tell they are contaminated. This type of contamination can be hard to reverse, too, if the contaminant is given enough time to absorb into the pad.
Avoid using spray lubricants and aerosols on a bike with disc brakes to avoid this type of contamination.
Rim brakes can also be contaminated by oil or lubes, but they are more susceptible to accumulating dirt, as well, because the braking surfaces are farther apart.
Glazed/Shiny Braking Surfaces Through Overheating
Brake pads and shoes can become glazed, making their surfaces shiny. This often occurs because of overheating through excessive braking.
The heated surface of the pad softens and is smoothed by further braking before cooling and hardening again. A braking surface that is tempered in this way can become noisy. Disc-brake rotors can also become glazed.
Brake Rub & Alignment
If you hear squeaking noises and/or detect friction while riding, it might be caused by a bent rotor or wonky rim-brake calipers.
With carbon rim-brake wheels, brake shoes can catch on the brake track under load, especially at the rear. This occurs because carbon wheel rims flex at the top, whereas metal rims flex at the point of contact with the road or riding surface.
Angle of Engagement & Frictional Drag (Rim Brakes)
If you install rim brakes so that the shoes make contact across their whole surface at once—flush against the brake track—it’ll often create a high-pitched squealing noise.
This comes about when the rotating rim produces surface waves in the softer rubber brake shoe.
As the brake shoe makes contact with the rim, its elasticity creates a caterpillar-like motion. The leading edge of the shoe (its rear end) follows the rim and resists it before returning to its original position to begin the motion again.
The remedy for this noisy occurrence is to slightly alter the angle of the shoe so it behaves like it’s already worn in. We’ll look at that later.
Before You Start: Items You Need To Fix Noisy Brakes
You don’t need much stuff to fix squeaky brakes, but there are items you can buy to either maintain or restore silence. Not all of them are bike-specific.
For Disc Brakes
- Drip Lubricant – use a drip lubricant from Finish Line or other manufacturers rather than spray lubricant to lube your chain.
- Tools – removing disc pads and disc rotors requires items like a Torx T25 wrench, a 2.5 mm Allen key or hex key, and a pair of needle-nose pliers.
- Disc Brake Cleaner – use disc brake cleaner to clean glazed or contaminated pads and rotors.
- Emery Cloth & Block – Use emery cloth with a block to de-glaze or decontaminate brake pads or disc rotors.
- Protective Gloves – a pair of protective nitrile gloves helps to avoid contaminating brake pads and rotors during cleaning.
- Other Protective Gear – wear a dust mask and safety goggles to protect yourself from solvent spray while cleaning disc brakes.
For Rim Brakes
- Isopropyl Alcohol – use isopropyl alcohol to clean the brake track on your rim-brake wheel or your disc-brake components.
- Clean Cloth – use a clean cloth to apply Isopropyl alcohol to the brake track.
- Fine Pick – use a sharp pick to remove pieces of debris embedded in brake shoes.
- Small File – to remove a glazed surface from rim-brake shoes, use a dedicated flat file that hasn’t been used elsewhere.
- Hex keys – with cartridge brake shoes, you’ll need 2mm and 4mm hex keys. A typical multitool like the crankbrothers M-10 should include these.
How To Fix Squeaky Rim Brakes
Rim brakes can squeak and squeal when they’re not worn in or when they’re contaminated and/or glazed.
1. Toe In New Brake Pads or Shoes
To avoid the surface motion of new brake shoes and the resulting noise, you should “toe them in”. This means positioning the leading edge of each shoe so that it’s marginally further from the rim than the trailing edge.
Remember: the leading edge is the rear of the shoe as you face the handlebar. The brake shoe gets pushed from the rear with the clockwise motion of the wheel.
To do this, first loosen the brake shoe so you can position the brakes squarely against the rim, avoiding any interference with your tire.
Next, clamp the brakes against the rim by pulling on the brake levers. As you do this, place a credit card or folded business card behind the rear of the brake shoe so that it’s fractionally farther from the rim. Tighten the brakes into position.
This simple adjustment is akin to immediately wearing the brake shoes in.
Video: How To Toe In Rim Brakes
2. Service The Rim Brake Surfaces
Brake shoes that are shiny (glazed) or wheel rims with braking residue on them can cause squealing. For the shiny brake pads, take the sheen off the surface using a small, clean file or a piece of fine emery cloth.
Study the brake shoes and pick any small pieces of debris out of them with a sharp pick.
Clean the brake track of your wheel rims by going around it with a clean cloth and isopropyl alcohol. If the bike is dirty, wash it first with soapy water to get most of the grime off, then rinse with clean water.
Video: Brake Maintenance & Cleaning
How To Fix Squeaky Disc Brakes
There are a couple of ways to stop disc brakes from squealing.
1. Clean Disc Brake Pads And Rotors
Remove brake pads using needle-nose pliers and a 2.5mm Allen key. You’ll need the tools to undo retaining clips and bolts.
Remove the rotor from the bike using the Torx T25 wrench or equivalent.
Clean the pads and rotor using isopropyl alcohol or disc-brake cleaner.
Use emery cloth to decontaminate or de-glaze brake pads and rotors. The rotor should have a satin finish rather than a shiny one.
Video: How To Clean Disc Brakes
2. Bed The Brakes In
For disc brakes to work silently, you need to transfer some material from the brake pads to the rotor. You should “bed them in” when new or after cleaning.
SRAM’s bedding-in method is particularly straightforward:
- Find a quiet area to ride with plenty of space.
- Build up to a moderate speed (let’s say 10 to 12 mph) and slow down to walking speed without skidding by gradually applying the brakes.
- Release the brakes without stopping and repeat the process 20 times.
- Do the same thing 10 times at a faster pace (let’s say 15 to 20 mph).
Video: Bedding In Disc Brakes
As you’ll have gathered, keeping brakes quiet is largely about maintaining a clean and viable interface, free of contamination, between brake pads and the brake track or rotor.
With rim brakes, you’ll be trying to prevent that “shudder” that occurs when the new brake shoes are shoved from the rear.
By following the above guidelines and ensuring your brakes are properly installed, you should be able to stop in silence!
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