You should clean your brake system any time performance drops or a pre-ride inspection uncovers dirt or grime in the system. Frequent cleaning is especially important for your brake pads.
Remove grime and residue from your brake pads using a cloth and alcohol, glass paper, or even a file. Brake pad surfaces should be soft enough that you can scratch them with your fingernail. Remove any foreign objects. To resurfacing worn or dirty pads cut any ridge off with a sharp knife. Flatten if by rubbing the ridge over sandpaper or use a file.
Wipe down and lightly lubricate your brake cables every few months. Lubricate by applying a teflon spray to the cable near the cable guides and housings. Be careful not to get lubricant on your pads or wheel rims.
The pivot points found throughout your brake system can be maintained by wiping them clean and by applying a very small amount of teflon oil to the pivot areas while moving them back and forth. Lube the point of friction where the arms of a cantilever are bolted on pivots fixed to the frame.
If the brakes feel heavy but the cables are OK, it indicates an overhaul is needed. Side pull brakes need more lube because they have more internal friction. Disassemble and clean them if it takes a lot of effort to squeeze the arms together.
You need to adjust the cables when the brake lever has a lot of travel. The cable adjuster is on the brake lever on cantilevers. Loosen the locknut and give the adjuster 2 turns counterclockwise. Continue this process until the brake lever feels almost solid. On road bikes the cable adjuster is on the brake arm. Loosen the locknut and unscrew the adjuster a few turns. If necessary loosen the anchor bolt, pull the cable through a bit and retighten.
You need to do the following if the brakes feel heavy and the cables need lubricating Your position is uncomfortable and you have to stretch when applying the brakes or you are installing new handlebars
Road bikes - lube the brake lever pivot; it may be sticky with old oil. Pull the brake lever and spray lube onto the end of the cable. If you need to adjust the brake lever position, remove the cable and using an Allen key, remove the clamp bolt that is at the back of the hood. Loosen the clamp bolt and pull off the handlebar. This will enable you to remove the brake lever without undoing the handlebar tape.
Mountain bikes - the pivots should be lubed regularly on mountain bikes because they are exposed. Lube the cable by pulling the brake lever and the cable adjuster. To remove or adjust the position of the brake lever, loosen the clamp bolt that is usually tucked under the shifter lever, where the gear shifter is fitted to the brake lever. You must push it fully forward to get at the clamp bolt. There may be a small Phillips screw just behind the cable adjuster. Try to adjust this so that you can make a stop using your 3 middle fingers only.
Identifying and solving braking problems
Brake levers typically malfunction for one of three reasons:
Your brake pads are not close enough to the rims
The system is not tight or fully "engaged"
Your levers are damaged or dirty
Always check that your brake pads are close enough to your wheel rims. Before you reposition them, however, check that the pads are not worn down too far, if so, replace them.
If your pads are okay, turn the cable adjustment knob counterclockwise until the desired pad to rim distance is achieved (1/8th of an inch is standard). The cable adjustment knob is either located where your brake cable enters your lever. On road bikes they are on the brake caliper.
Most modern braking systems have some sort of quick-release mechanism that allows you to loosen the cable system without affecting your brakes effectiveness. This is the 'slack' in the system needed to open the brake arms wide enough to get your wheel out. Some quick-releases are located on brake assemblies; others on brake levers or elsewhere along the cable route. If you find too much 'slack' in your braking system, first check these quick-release mechanisms to make sure they are engaged properly.
If however your brake quick-releases are connected properly but brake levers still function poorly, the levers themselves may need cleaning or repair.
Incorrectly positioned brake assemblies or brake pads
Poorly positioned brake assemblies can cause ineffective braking and/or brake squealing.
Solution - Brake pads and brake assemblies are usually held in place by simple systems of binder bolts, washers and mounting nuts. Re-adjustment in most cases involves little more than loosening the appropriate nut or bolt, maneuvering the assembly into the proper position, and tightening the binder bolt again to keep the component in place. Because of the large number of brake designs available, detailed descriptions of specific adjustments are not included. Take some time to familiarize yourself with your brake assemblies and how they're put together, so you can make basic adjustments if necessary.
Improperly gripping brakes
If your brakes still grip poorly after you've checked your levers and assemblies, your brake system may need professional adjustment. But before taking the bike to your nearest CoBR member, check for the following:
Dirty rims can cause poor braking performance. Check your rims and clean them if necessary.
Worn or "glazed" pads. Rim grime, general brake use and time can all cause your brake pads to become hard, slick and ineffective. Check the surfaces whenever braking performance drops or your brakes "squeal". Glazed or hardened pad surfaces should be cleaned or replaced.