Last week we covered basic drive train preservation and care. Now that you’re moving, let’s talk about stopping. Most people on mountain bikes these days have disc brakes, heck a lot of road bikes are being made with them now too. There are generally two types of disc brakes, mechanical or hydraulic. The most common, and effective for mountain biking are hydraulic, so that’s what I’ll focus on.
Let’s break it down.
The wear components of your braking system are the pads and the rotors, and less often the hydraulic fluid and brake hose. If you ride for extended periods of time on pads that are worn out you consequently will wear out your rotors. If your pads are completely smoked it will also make a terrible noise and your friends will not want to wait for you at the top of the next hill.
Propper caliper set up, will allow your pads and rotors to last longer, and result in more effective braking. More effective braking means less braking, less braking means less heating of the rotors and consequently less heating of the fluid in the line. Fluid loses its integrity when it’s repeatedly boiled. Your pads and rotors will still wear out eventually unless of course, you are dragging your heels to slow down, which we generally don’t recommend. Replacing pads and rotors in a timely fashion, will save you heartache and make your bicycle perform better. And your friends will actually want to ride with you because you won’t sound like a banshee fighting an alley cat every time you pull the lever.
You can periodically check the rotor for wear, a stamp on the rotor indicates minimum width, if you don’t own a handy dandy digital caliper come see us at the shop in town. We can check ‘em for ya.
Here is how to set up your brakes correctly, specifically the caliper (that’s the part with pads). A hydraulic caliper functions at its highest capacity when it is positioned with the rotor perfectly centered inside of it. The pistons, those are the ceramic circle-shaped things that push the pads when you pull the lever, are clean and move in and out equally from the left and right sides. When the caliper is caddywhompus even a little, or the pistons are sticking, the result is diminished stopping power, and a shorter life span for the pads, rotor, and hydraulic fluid.
(photo right shows the minimum width stamp on a rotor, and wear pattern to the braking surface.)
Here’s what I do when I service your brake caliper. With the wheel out, I remove the pads, examine the pistons to see that they are all moving harmoniously, and they almost never are because y’all ride hard and dirty. I use a clean rag to thread through the opening, removing debris from the inside of the caliper. If the situation is ultra nasty and it often is, I use a q-tip to wipe the gunk from around the pistons. Once everything is clean I employ a plastic tire lever to reset the pistons. I press from the center of the piston to keep them flat and use a plastic lever to prevent breakage. While watching closely I pull the lever gently and make sure the pistons are moving equally from both sides of the caliper, cleaning and resetting as many times as necessary to make it right. If the brake needs a bleed, this is when I perform that function.
Once the pistons are flowing nicely, I loosen the mounting bolts on the caliper and replace the wheel on the bike, without reinstalling the pads. This allows me to see very clearly if the rotor is centered, and if the rotor is true (true meaning no wobbles or bends). After aligning the caliper with a true rotor and making sure it is centered I tighten the mounting bolts. Now I remove the wheel, reinstall the pads, and replace the wheel again. I reset the pistons by pulling the lever a few times until it engages. Once the pads are set I spin the wheel and listen for rubbing, small little rubs may be adjusted by loosening the caliper mounting bolts and moving the caliper until the noise subsides. If the rubbing noise is substantial I likely have to recheck the true of the rotor and the equivalence of the piston position.
(Rear caliper pictured left, positioned with a centered rotor, pads installed, before pistons are reset. Kona Process 153)
You do not have to do everything I do when you care or your bike. But here are a few things you can do to limit the number of pads you buy, lessen the number of times you require service and have more effective stopping power.
- 1. Replace your pads before they absolutely need to be, at about 75% wear.
- 2. Replace your rotors before they reach minimum width.
- 3. Ensure the rotors are true and the caliper is centered. Remember effective braking is sustainable braking.
- 4. Keep your bike clean, wiping dust and dirt off after each ride! Prevent the dirt build-up that causes pistons to stick. Isopropyl and a clean lint-free rag can be used to wipe rotors.
Thank you for reading! We are gleefully watching snow melt waiting for the trails to reveal themselves. Come back next week for info on wheels and tires! Habitat in town is open 7 days a week from 10am-6pm.
Images and words by Carolyn Keefe