The beauty of disc brakes is that they require very little maintenance, but there are few tricks to ensure you get the best performance out of them and ensure they keep working nicely.
If you’re reading this article it’s safe to assume you have a bike (road, cyclocross or adventure) with disc brakes, and if you’re new to discs you might be wondering how you can look after them to ensure the work reliably and consistently? We’ve got some top tips to keep your brakes in tip-top condition.
Disc brakes might seem scary but really they are no more difficult to look after than rim brakes, and in our experience, they actually require less fettling. But there are a few things you can do to ensure they work well all of the time.
Bed your brakes in
We’ll start with a top tip for anyone that has just bought a new disc brake bike. Brand new disc brakes won’t deliver their full power out of the box, and that’s because the rotor and pads need bedding in.
Bedding in the pads will prepare the surfaces of the disc rotor and pads by distributing pad material over the rotor to improve the friction between the two parts. Bedding in brakes is really easy but it’s worth doing before you head out for that first ride.
SRAM has a really good guide for bedding in disc brakes, and it’s advice that has worked for us:
Accelerate the bike to a moderate speed and then firmly applying the brakes until you are at walking speed. Repeat this process 20 times. Then accelerate the bike to a faster speed and apply the brakes until you are at walking speed. Repeat this process ten times. It’s important that during this process you never come to a complete stop or lock up the wheels at any point.
Doing this process should drastically improve the performance of your brakes and prepare them for many happy rides.
This is the most annoying complaint with disc brakes. It was a more frequent issue with early generation disc road bikes but the adoption of the flat mount standard and most wheel and frame manufacturers improving manufacturing tolerances has led to rubbing brakes being much less of an issue than they ever used to be.
If your brakes are rubbing though, what can you do to sort them? The first thing I would always recommend people try is centring the caliper over the rotor. To do this, simply slacken off the caliper bolts, spin the wheel, then with the brake lever applied, tighten the bolts. Most of the time this tip works a treat. Occasionally I might have to do it twice but it usually works for me.
Squealing pads can also be a sign that the pads are worn out. It's a little more tricky to take a closer look at disc brake pads compared to rim brakes, taking the wheel out can make the task a little easier. If you do need to replace pads, you might be wondering what sort of pads you need. Yes, disc brake pads come in many flavours - here's our handy guide.
If the brakes are still rubbing, then you might have a bent rotor, which leads me onto…
This is mainly an issue if you’re travelling or flying with the bike, the thin aluminium rotors can bend if enough force is applied. If flying you can remove the rotors, an easy job with the CentreLock rotors that are increasingly taking over from older six bolt rotors. The other option is to make sure you pad the rotors very carefully
What to do if you do have a bent rotor? Slowly rotate the disc rotor in the caliper to see where it’s out of alignment, then very gently using an adjustable spanner with a rag protecting the rotor, bend the rotor a small amount. Repeat until the rotor is straight. You can use a dedicated tool to do this like the Park Tool Rotor Truing Fork, but it’s an additional expense.
Here’s a good video by Park Tool for straightening a bent rotor.
My brakes won’t stop squealing
Squealing brakes can occur for a number of reasons. Usually, it’s a sign you’ve got grease or oil on the brake pad or rotor, an indication that the pads and rotor are contaminated, either from cleaning the bike or residue picked up from riding.
One of the most common causes of a noisy brake is contamination. 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 really.
Contamination just means oil, meant to keep your drivetrain running smoothly and quietly, has found its way onto the brakes. So try and avoid getting oil or lube on the rotors and pads.
With spray lubes this is very easy to do. When you are cleaning your bike be sure to prevent any spray getting anywhere near the brakes. If using a spray can use a thin straw (one is normally supplied) to direct the oil to only the area of the drivetrain you want it, and away from the brakes.
Or you can put a shield between the drivetrain and disc brake, such as the Eat Me Dirt Brake Shield we reviewed last year. Or you could make your own with some cardboard.
What happens if you do contaminate the brakes?
If you’ve only got a small amount of oil on the brakes, you can clean brakes with a degreaser, or pick up one of the dedicated disc brake cleaners available on the market (we’ve linked a few we reviewed below) and hopefully you'll be able to clean the worst off. Once clean, normal riding conditions should generate enough heat to bring the brakes back to the optimum working conditions.
“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.
Here are a couple of disc brake cleaners we’ve reviewed that you could try:
Alternatively, and more cheaply, you can use an isopropyl alcohol available from some electronic stores. Apply some to a rag and use it to wipe the disc rotors. You’re just trying to remove any residual oil and muck.
Now turning our attention to the brake pads, first use the same cleaner you used for the rotors or lots of detergent and water, and scrub the pads with a brush. If the pads aren’t too contaminated you might be able to save the pads.
Another method is to use a fine sandpaper and scrub away the surface of the pads to remove any glazing or dirt. Depending on how bad the contamination is, these steps can usually cure the brakes.
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. That’s not something you’ll find any of the disc brake manufacturers recommending at all.
If those tips don’t cure your brakes, then you might be needing to replace the brake pads I’m afraid. If you’re not sure what sort of brake pad you need, and there a few key choices, have a read of the linked article below.
The great thing about hydraulic disc brakes compared to mechanical discs and rim brakes is that the calipers automatically adjust for pad wear. So, as the pads wear, the pistons move out of the caliper to keep the distance to the rotor the same. It’s a key advantage over rim brakes.
However, you do need to be careful when you’re taking the wheels out of the bike, whether for transportation or storage. If you pull the brake lever with the wheel out the pads will move out, and you won’t be able to get the wheel back in. It’s something we’ve all done here once or twice at road.cc.
Thankfully the solution is an easy one. You could get some specific pad spacers (SRAM and Shimano make them) or improvise with a thick bit of cardboard, and simply place between the pads after you’ve removed the wheel. Now if you accidentally pull the brake lever the pads won’t pop out.
If you forget to do this and the pads do squeeze out, you need to push them back in. We suggest taking a thin flat blade screwdriver and very gently, being careful not to damage the pads here, prise the pads apart. Then swap to a tyre lever or rounded spanner and wiggle the pads apart, pushing the pistons back into the caliper. It shouldn’t require much force. Now reinsert the wheel and pull the brake lever a few times and they should be perfect.
Hydraulic brakes should have a nice firm lever action. If the brake lever feels mushy and spongy, it’s a sign that there is air in the system and is going to require bleeding. It’s very rare for air to get into the system, a hydraulic brake is completely sealed, and it’s possible to go years without ever having to bleed the brakes, so don’t fear, it’s not something you’ll have to worry about doing frequently.
If you’re not confident bleeding your brakes then take your bike to a reputable bike shop and let them do it. They’ll have all the necessary tools and expertise to do it quickly and properly and it’s a lot less messy than the first time you try to do it yourself at home. I’m talking from personal experience here.
To carry out the bleed at home, you’re going to need a bleed kit. Each manufacturer has their own bleed kit, they’re not compatible with each other - Shimano and SRAM use very different techniques and fluid. So buy the bleed kit for your brake system and follow the supplied guides, or watch our how to bleed brakes video below.
Follow those tips and you should have disc brakes that work well all of the time. If you have any more questions don’t hesitate to ask them in the comments section below.
David has worked on the road.cc tech team since July 2012. 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.