Work out which brakes you have first
Everything else follows from this, and it takes one look.
Rim brakes squeeze the wheel rim itself. The pads are blocks of rubber sitting either side of the rim, mounted on arms that reach up from the frame or fork. If you can see the pads touching the rim when you pull the lever, you have rim brakes. Older road bikes usually have caliper brakes, older mountain bikes and hybrids usually have V-brakes with longer arms.
Disc brakes squeeze a steel rotor bolted to the wheel hub. The pads are small rectangles hidden inside a caliper at the centre of the wheel. If you can see a slotted metal disc near the hub, you have disc brakes.
Disc brakes then split again. Hydraulic systems use fluid in a sealed hose and self-adjust as the pads wear. Mechanical or cable-actuated systems pull the caliper with a cable, like a rim brake, and need manual adjustment. You can tell them apart by looking at what enters the caliper: a thin bare cable with a visible adjuster is mechanical, a thicker sealed hose is hydraulic.
Our guide to disc versus rim brakes on used bikes covers the buying decision. This one covers the maintenance.
When pads need replacing
Rim pads have grooves moulded into them and a wear line. When the grooves are gone the pad is finished. Look also for the pad wearing unevenly, for grit embedded in the rubber, which will chew through a rim, and for hardened, shiny pads that squeal and stop poorly.
Disc pads wear until the friction material is roughly the thickness of a credit card, around one millimetre above the metal backing plate. Below that, replace them. If you can hear metal on metal you have already gone too far and you may have damaged the rotor as well.
Two symptoms that mean stop and check now: the lever pulling all the way to the bar, and any grinding sound under braking.
Changing rim brake pads
You need a 5mm allen key for most pads, sometimes a small spanner, and often nothing else.
- Release the brake. On a caliper brake there is a small lever on the caliper body. On a V-brake, squeeze the arms together and unhook the noodle from its cradle. This gives you room to work.
- Note how the old pad sits. Take a photo before you remove anything. Pad holders are usually left and right specific and there are often several curved washers that must go back in the same order.
- Undo the fixing bolt and slide the old pad out. Cartridge pads slide out of a metal holder once a small grub screw or retaining pin is removed. One-piece pads unbolt completely.
- Fit the new pad. Match any direction arrow, and match forward on the pad to forward on the bike. Some pads are open at one end and will slide straight out under braking if fitted backwards.
- Set the position. The pad must sit squarely on the braking surface of the rim, a millimetre or two below the top edge, and must not touch the tyre. Rubbing the tyre will destroy it. Pull the lever gently to hold the pad against the rim while you tighten, so it settles in the right place.
- Add toe-in. Angle the pad so the front edge touches the rim slightly before the rear edge. A business card held behind the back half of the pad while you tighten gives about the right amount. This is what stops rim brakes squealing.
- Reconnect and test. Re-hook the noodle or close the quick release, then squeeze the lever hard several times and check the pads are still where you put them.
Changing disc brake pads
You need an allen key, usually 2.5mm or 3mm for the retaining pin, and a clean pair of hands.
- Take the wheel out. Much easier than working around it.
- Do not squeeze the lever with the wheel out. On a hydraulic brake the pistons will close on nothing and you will have to prise them apart. It is recoverable, but it turns a five minute job into a fiddly one. A plastic transport spacer wedged in the caliper prevents it, and every bike shop has a drawer of them.
- Remove the retaining pin. Straighten the split pin or R-clip on the end, then withdraw the bolt or pin that runs through the caliper.
- Pull the old pads out. They usually come out upwards or downwards together with a small spring clip between them. Note which way round the spring sits.
- Push the pistons back. With the old pads out, use a proper piston press or a clean plastic tyre lever to press each piston gently back into the caliper body. They will have crept out as the old pads wore, and new thicker pads will not fit until they go back. Press evenly and slowly. Never use a screwdriver, which will scar the piston.
- Fit the new pads with the spring. Sandwich the spring between them and slide the assembly in the way the old ones came out. The friction material faces inwards, towards the rotor.
- Refit the pin and secure it. Then refit the wheel and check the rotor is running freely in the middle of the caliper.
- Pump the lever. Squeeze it repeatedly until it firms up. The first few pulls will feel long as the pistons take up the gap.
Keep everything oil-free. Disc pads and rotors are ruined by contamination, and fingerprints are enough. Handle new pads by the metal backing plate. If you get oil on a rotor, clean it with isopropyl alcohol. If you get oil into a pad, the pad is finished.
Bedding in
New pads do not work properly straight out of the box. The friction material has to transfer an even layer onto the rim or rotor first, and until it has, braking will feel weak and may be noisy.
Find a quiet, flat road. Ride at a moderate speed and brake firmly down to walking pace without stopping completely, then release and ride back up to speed. Repeat around ten times, then do a few harder efforts from a higher speed. The brakes should feel progressively stronger. Do not come to a complete stop while the rotor is hot, because that presses one patch of pad material onto the disc and creates the uneven deposit that causes a pulsing feel.
Do this before you rely on the brakes in traffic or on a descent.
When to hand it to a shop
Pad replacement is one of the most approachable jobs on a bike. Some neighbouring jobs are not.
Get a shop to do it if the lever still feels spongy after new pads, which usually means the hydraulic system needs bleeding. Also if a rotor is visibly warped, if a piston will not retract, if there is fluid weeping anywhere around the caliper or lever, or if the mounting bolts have been rounded off. Brakes are the one system where guessing is not worth the money saved. Our bike shop directory lists independent workshops across the UK.
If the bike is one you have just bought used, it is worth a full check rather than just the pads. The used bike inspection checklist covers what else to look at, and the complete maintenance guide covers the jobs worth doing next. Every bike with a frame number listed on Cyclesite is checked against a stolen-bike registry and rider-filed theft reports before it goes live, and you can check any frame number yourself before money changes hands.
Common questions
How do I know when my bike brake pads need replacing?
On rim brakes, replace the pads when the moulded grooves have worn away. On disc brakes, replace them when the friction material is around one millimetre thick, roughly the thickness of a credit card. Any grinding noise or a lever that pulls to the bar means check them immediately.
How long do bike brake pads last?
It depends far more on conditions than on mileage. Winter riding on wet, gritty roads can wear a set of pads out in a few hundred miles, while the same pads may last a couple of thousand in dry summer conditions. Check them regularly rather than working to a schedule.
Can I change bike brake pads myself?
Yes. It is one of the simplest jobs on a bike and needs only an allen key for most brakes. The parts to be careful with are keeping oil off disc pads and rotors, not squeezing a hydraulic lever with the wheel removed, and bedding the new pads in before you rely on them.
Why are my new brake pads squealing?
New pads squeal until they have bedded in, so do that first. On rim brakes, persistent squealing usually means the pads need toe-in, with the front edge contacting the rim slightly before the rear. On disc brakes it usually means contamination on the rotor, which can be cleaned with isopropyl alcohol.
Do I need to bed in new brake pads?
Yes. Ride at a moderate speed and brake firmly down to walking pace around ten times without coming to a complete stop. This transfers an even layer of pad material onto the rim or rotor. Until it is done, braking will feel weak.
Google then shows our guides more often, including in its AI answers.
Last updated · Editorial standards · Corrections