- David B.
How to Check and Change Your Bicycle's Brake Pads
Updated: Nov 10, 2021
Sometimes it’s the little things that make the biggest difference. Whether riding a mountain or road bike, your disc brake pads undoubtedly fall into this category. When working properly, you barely notice them, as they seamlessly—and silently—slow you down. But when overly worn (they don’t last forever, after all), disc brake pads can emit an ear-splitting shrill, damage your brake rotors, or even fail to work altogether. Thus it’s critically important to examine your disc brake pads from time to time, and replace them when necessary. The good news is that with the right tools and little know-how, this is a fairly simple job that can be done by even a novice home mechanic.
How to Check
Often your disc brake pads will provide clues that it’s time for a new set. Hydraulic disc brake systems automatically adjust clearance as your pads wear, but if you’re using cable actuated mechanical disc brakes, your brake lever will pull closer to the handle bar as the pads wear. Initially you can remedy this by taking up slack with the barrel adjuster, but soon it will be time to swap in a new pair of pads.
Other signs of pad wear for both mechanical and hydraulic braking systems include low power braking and a high pitched howl or metal-on-metal sound, which is a sign that your pads are completely worn and that the metal backing plate is now contacting your rotor. This can damage your rotors and should be remedied immediately.
But best to avoid this proverbial breaking point, which means occasionally checking pad wear so you can replace them before they start causing problems. To do this, first place your bike in a bike stand and remove both wheels, which makes it easier to inspect your pads. Once the wheels are removed, take care not to squeeze your brake levers, as on a hydraulic system this will push out the pads and pistons and may necessitate a brake bleed.
Now closely examine brake pad thickness. Pads typically start with 3-4mm of braking compound. They should be replaced when there’s 1mm or less left (roughly the width of a credit card). If everything looks good, reinstall your wheels and resume riding. But if there’s excessive wear, it’s time to install new pads. As for how long pads typically last, there’s no definitive answer. Factors such as rider weight, wet-vs-dry condition riding, and how much you actually use your brakes all play a role.
It’s also worth noting that excessive braking noise can also be caused by contaminated pads, say for instance if you accidently spill chain lube on you rotor and it then gets on your pads. If this happens a new set of pads may be the only remedy even if the existing pads have plenty of life left. Thus it’s very important to keep your brake pads clean and contaminant free.
Tools for the Task
Before beginning the replacement process gather the necessary tools, which include a wide/fat flathead screwdriver or pad pusher tool, needle-nose pliers, paper towels, isopropyl alcohol, and the appropriate replacement pads. In most instances you’ll also need a smaller flathead screwdriver or appropriate-sized hex key to remove the retention pin that holds the pads in place.
Here it’s worth pausing for a moment to discuss the three basic types of disc brake pads (sintered, organic, semi-organic), and why you might choose one over the other. Sintered or metallic pads are made from hardened metallic particles and provide a long lifespan and good performance in wet conditions, but can sometimes be noisy. Organic (aka resin or non-metallic) pads are made from organic materials and bound together with resin. They utilize a softer compound, which helps provide more initial bite and lessens the chance of excessive noise. However, they typically don’t last as long as sintered pads and are not as effective in wet conditions.
Option No. 3 is semi-metallic, which as the name indicates, utilize a blend of metal and organic materials and strive to provide a best of both worlds solution. Bottom line, there is a wide variety of stock and aftermarket pads to choose from. When in doubt it’s best to replace like-for-like. Each brake maker will provide recommended pads, so just be sure the ones you buy are labeled with your specific brake model.
Remove Old Pads
First remove the retention pin that secures your pads to the brake caliper. In most cases you’ll first need to take off the small safety clip that prevents this pin from falling out even if it comes loose. Next remove the pin, which is usually done with a 3mm hex key, though some set-ups require a small flathead screwdriver. Set these pieces aside in a safe place. Now using your needle-nose pliers pull the pads out of the caliper. Each pad set will consist of three parts, the two pads plus an H-spring that goes in the middle and helps the pads retract when released.
With the pads out, you’ll be able to examine pad thickness more closely and definitively decide if it’s time for a new pair. No matter what you decide, take this opportunity to give your calipers and rotors a quick bath in isopropyl alcohol, wiping away dust and grime with a paper towel.
Insert New Pads
Before inserting your new pads, use a wide/fat flathead screwdriver or pad pusher tool to gently separate the pistons. This will make it easier to slip the new pad into place. Now grab your new pads and place the H-spring in the middle, making sure not to touch the pad material, which can cause contamination. Next slide the new pads into the caliper. Some models will insert from the top, other through the bottom. Finally, reinsert the retention pin and secure, remembering that this is a low torque bolt, so it need only be snug not overly tight. Also don’t forget to reattach the safety clip.
Now you’re ready to remount your wheels. Ideally your rotors will slide right in between the new pads without rubbing, but oftentimes you’ll need to make slight adjustments. This is done by loosening the bolts that hold the caliper in place, then moving the caliper so that the rotor is perfectly centered between the new pads. Now retighten the caliper-fastening bolts and check alignment. Repeat as necessary until the rotor spins freely without touching the pads.
Lastly, remember that for optimal performance, new brake pads must be bedded in. The general recommendation is to do 10 hard stops at slow speed. Do this by taking a few easy pedal strokes, and then give your brake levers a strong pull. Once that’s done you’re ready to head back out on the road or trail, knowing that your brakes will slow you down not let you down.