How to Adjust Your Disc Brakes
Author: Ben Malvern
How to Adjust your Disc Brakes
In order to achieve the best possible performance from your brakes, they need to be properly adjusted. If your brakes are rubbing it’ll cause uneven wear, reduce power, and leave you feeling less confident in your bike’s ability to slow down; not to mention, the sound of rubbing brakes is enough to drive a man (or woman) crazy. Regular safety checks on your brakes should be performed to prevent safety hazards. The following steps will tell you how.
How to know your Brakes need Servicing
Your brakes need servicing if:
-The lever pulls to the bar or doesn’t pull at all
-Lever has a spongy feeling
-Grinding or squealing
-Brakes are rubbing or are noisy
-Lack of power or oscillation occurs
-You have not maintained them
Check the brake caliper located on either the rear or front of the bike to check if it is a hydraulic or mechanical disc brake. If you can locate a steel cable sticking out of your brakes, then you have mechanical disc brakes. Fundamental adjustments still apply, but adjustments and symptoms will differ from hydraulics. Hydraulic brakes may require special tools for service, but adjustments on either kind should be easy.
Where to Start
For disc brakes, you’ll need a set of Allen keys. Also, make sure that all tools and surfaces are clear of grease or contaminants, and make sure to have isopropyl alcohol or a dedicated brake cleaner. Many types of cleaners are not safe to use on brakes, because they can contaminate them.
Start by ensuring your brake pads have adequate life left. There should be at least 1.5mm of material left on each pad.
1. Step One (What your lever feels like, and what it means)
When you pull the lever, it should feel easy, and it should have a bit of a dead zone (Roughly 1 cm of no engagement, but this varies with different manufacturers). When the brake does engage, it should feel firm and not spongy. If you have hydraulics and the lever pulls to the bar or has a spongy feeling when pulled slowly, this means that you need to bleed your brakes, or that you should get new brake pads.
Take a quick look at your pads and if they have adequate pad depth, then you likely need a brake bleed. This can be a challenging service to do if you’re unfamiliar with bike maintenance, but if you’re up for the challenge, it’s a useful skill to have; Otherwise, connect with a local mechanic and they’ll be happy to help.
When pulling the lever, it should be fairly easy. If it feels gritty or sluggish, then you’ll need a new cable, and possibly new housing. Installing cables is fairly straightforward but can be tricky the first time. If you’re unsure of how to proceed with new cables, get in touch with a local mechanic through our site, and they’ll be happy to make the install.
If the lever pulls to the bar or hits your knuckle, this can be corrected by tightening your cable. Loosen off the pinch bolt (blue) with an Allen key, and then, apply tension to the cable while re-tightening the bolt. Feel the brake again and if it still pulls in too far or too little, then try turning the micro adjuster (red) a couple of turns (counterclockwise adds tension to the cable, and clockwise reduces tension). The more tension on the cable, the less you need to pull in the brake. However, try not to dial the micro adjuster too far outwards. Too much tension can make it challenging to align the brake in later steps.
2. Step Two (Why your brake is Rubbing)
Once the pull is correct, ensure that the brakes do not rub. For this step, it will be easiest to place the bike in some form of a stand. Give the wheel a spin. If the brakes rub, then the wheel will stop quickly, or you will hear a rubbing sound. This means one of three things: Either your caliper isn’t aligned, your wheel isn’t straight, or your rotor is bent (all rotors will have some minimal bend). Start by making sure your wheel is straight in the dropouts, because this can cause rubbing and poor shifting.
3. Step Three (Adjusting the Caliper)
If rubbing continues after straightening your wheel, adjust the caliper by loosening off the mounting bolts. Keep the bolts tight enough that the caliper doesn’t move around on its own, but loose enough that you can move it intentionally. Try to manually align the caliper with the disc by eye, while checking to make sure the disc isn’t rubbing, and tighten the bolts back down.
For those that do not know, the caliper is the portion of the brake surrounding the disc.
A useful trick if you’re stuck:
Try to insert a plastic card on both sides of the disc inside of the caliper. When you do this, it creates space between the pads and rotor and aligns the caliper, and then you can tighten the bolts down. A common mistake when re-tightening the caliper is tightening one bolt too much, which can cause the caliper to move out of alignment. Try to tighten the bolts evenly.
4. Step Four (Inspect Pads)
This is an optional step. A lack of power and noisy brakes can be the product of many different things, but the most common is glazed over or contaminated pads. If your brakes are squealing, sometimes they can be saved, but if they’re overly contaminated you will need a new set of pads. To take your pads out, remove your wheel and then remove the retaining pin. The pads should then slide out. Inspect the pads for any signs of glazing over or contamination. Glazed over pads will appear reflective or shiny.
5. Step Five (Cleaning Braking Surfaces)
To clean the pads there are a few different methods, but the one I have had the most success with is to lightly sand down the surface. Once you’ve sanded a thin layer off the surface and the pads look clean, you should also clean the rotor.
Use brake cleaner or Isopropyl alcohol to ensure no residue is left on the rotor. Then, carefully re-insert the pads. Make sure to bed them in by pulling on the brakes lightly as you ride, so that they seat into the rotor better. Do not make any hard stops until the “bed-in process” is completed with some light riding.
It is important to quickly check on your bike every few rides. Brake performance degrades with time, so make sure to stay on top of service. Casual riders can usually go a couple years without needing to replace brake pads, but it’s important to keep an eye on them.