How-To: Regain Control of your Brakes
Over time, even the best brakes will steadily loose their shine. Here's how you can give them a new lease of life.
What You'll Need
Worn or contaminated pads will need replacing and you need to ensure the new pads are compatible with your callipers; every brand and model will be different.
Aside from some new pads, you'll also need disc brake cleaner, bleed block or suitably sized implement for pushing the pistons home (we used some nylon tyre levers) and some general tools—allen keys, torx tools and so on.
Other handy items include a set of verniers, a torch and some emery paper.
STEP BY STEP
1. If you notice the brake lever pulling further in towards your grip, even after you’ve pumped the brake a few times, it’s best to inspect the pad thickness. Take a look down inside the calliper and inspect the thickness of the pad material—shining a torch down there will help.
2. If it’s hard to see into the calliper – or if there’s a clear lack of pad material – you’ll need to pop the pads out of the brake. The pads are typically held in place by a threaded bolt or a split-pin. If it’s the threaded type (as pictured), check for additional ‘security circlips’ that you may need to remove before the bolt is undone. Once the bolt is out, most pads will unload through the top of the calliper (although some come out the other way). Pinching the pads together in a sandwich usually helps and don’t force anything—just get the angle right and they’ll slide out.
3. A good pad will have around 1.5 to 2mm of friction material while a dead one will have less than 1mm remaining. Check your pads with some verniers if you’re unsure; the total thickness of a new SRAM Code pad (left) is a fraction under 4mm and 2mm of that is the backing plate. At 3.54mm (approximately 1.54mm of friction material) our pads still had some life in them but we'll replace them for the sake of this article!
4. As your pads wear, the pistons gradually extend from the calliper to compensate. If you’re about to install new pads, you’ll need to push the pistons back into the calliper to reset them. Care needs to be taken here as you don’t want to damage the pistons or push them in at an angle. We're using some flat nylon tyre levers but the rubber coated handle of a cone spanner or a suitably sized brake bleed-block will also work. Gently lever the pistons and push them back in little by little. You’ll need to work your way around the calliper, doing one side and then the next. Repeat until the pistons are pushed all the way home.
5. Before installing the new pads, thoroughly clean the calliper with disc brake cleaner and an oil-free rag. Make sure you run the rag through the inside of the calliper to remove any dirt, grease or anything else that could mess up your brand new pads.
6. Make sure the pads are properly assembled before installing them (some models can be left and right hand specific). Most will have a spring mechanism that holds them away from the rotor and stops them rattling. In some cases the spring requires correct orientation too—best to check the manufacturer’s instructions if you’re unsure. With everything in place, hold the pads and spring together in a sandwich and slip it back into the calliper (the opposite of how they came out).
7. If your pads were really worn, it’s best to check the condition of your rotors too. Grab your verniers and measure the thickness of the brake track. With most brands, a fresh rotor will be 1.8mm thick (Magura is one exception with 2.0mm rotors). If your 1.8mm rotors measure 1.5mm or less, replace them with a new set. Our SRAM rotors measured 1.73mm (1.8mm when new) so they've still got plenty of life left!
8. Before refitting the wheel, remove any residue from the rotor with disc brake cleaner and a fresh oil-free rag. You don't want to contaminate a brand new set of pads before you even hit the dirt! It only takes the tiniest amount of oil to ruin a set of pads, so once they’re clean, don’t touch the rotors. If the rotors are particularly old and have seen better days, you can sometimes improve their performance by giving them a light sand with some emery paper prior to cleaning them.
9. With the wheel back on the bike, pull on the lever a few times until the pads contact the rotor. Now spin the wheel and check for disc rub. If the wheel doesn’t spin freely, undo the calliper bolts and pull the lever in. While holding the brake on, snug up the calliper bolts—this should re-centre the calliper over the rotor. If this doesn't work, you'll need to exercise some patience and align it manually—ideally the calliper will sit parallel to the disc with even pad spacing on each side. Now you just need to bed the new pads in before hitting the trail!