The adjustment procedure for brakes varies considerably depending on the style and particular model but certain considerations are always present. I will address several common scenarios and the steps for correcting them.
On any bike, brake pads wear out wear out more rapidly than many other parts. Depending on several variables, they may last several seasons or merely a fraction of that time. If the bike is used in wet conditions, the pads will wear out a bit more rapidly. The tires transfer a slurry of sand, water and other debris onto the rims and brake pads. This mixture of water, sand and flecks of anything else from the road are driven against the rim surface by the pads each time the brake is applied. Over time, this may peel up a few small slivers of metal from the rim. Occasionally, these fragments of metal will become lodged in the surface of the brake pads and create a rather unbearable scraping noise when the brake is applied and the metal in the pad scrapes against the metal braking surface of the rim. A small pick can be used to dislodge these shards of metal and eliminate the noise. This cleaning also aids in preventing premature rim wear.
The pads will wear faster in wet conditions and care must be taken to replace them in time. Most pads have some kind of depressions cast into their surface. These marks serve as visual indicators of pad wear. When these marks wear away, you know that the pads are nearing the end of their life. Eventually, the pad will wear away to the metal shank it is cast around. This condition will be immediately evident in the noise produced by the metal shank grating on the rim’s braking surface.
Another condition that may develop as rubber brake pads dry out is a glazing of the braking surface. This metal residue reduces the friction produced by the brake pad and in turn, your braking power. Depending on how dry and cracked the pads are, they either need to be cleaned or replaced. Cleaning involves opening up the brake and removing the wheel to allow access to the pad surface. Using a coarse file, lightly and evenly abrade the pad surface. When the surface appears uniformly dull and the shine has been removed, reassemble and test them.
The pads should contact the rim at the same time and come to rest at the same point on the braking surface of the rim. If they push up over the top edge of the rim they will eventually contact the tire as they wear. If that set of circumstances lasts for many miles, the pad may wear through the tire surface and necessitate the replacement of the tire and tube.
Cleaning and lubricating the brake assembly and brake cables will increase the lifespan of all parts involved and make the bike more pleasant to operate. The frequency with which this needs to be completed depends on several conditions. If the bike is ridden regularly in the rain or in other inclement conditions, this lubrication process may be a monthly duty. On the other hand, it could only be twice a season if conditions and maintenance allows.
Certain brakes require particular attention periodically. Corrosion and grime will cause a road brake caliper to become sluggish and sometimes reluctant to move the pads away from the rim. They will eventually need to be overhauled in order to correct this issue. There are one or two pivot points that will need to be cleaned and lubricated. The whole brake caliper must be taken apart and cleaned. If attempting this for the first time, be cautions of the order in which parts fit together. Also, several setscrews are present and forcing out the bolts they hold in place will result in stripping threads.
The primary thing is keeping your pads clean and replacing them in a timely fashion to prevent premature rim wear and poor braking quality. These aspects can be monitored visually and prevent the development of larger, costly difficulties. Now you are ready to check the brakes and go for a ride.