Disc Brakes

Disc brakes work by basically the same principal as any other brake: pressing rubber pags against a metal wheel to keep the wheel from spinning. In the case of disc brakes, the metal wheel is not the wheel of the bicycle, but an additional wheel added to the hub for the specific purpose of braking.

The metal wheel attached to the hub of disc brakes is called the rotar. A calliper, attached to the bike's frame, houses two rubber pads that fit around the rotar. When the brakes are applied (mechanical disc brakes use the same cable, housing, and levers as a Calliper or V-Brake), the rubber pads slow/stop the rotar, causing the rear-wheel to likewise slow/stop.

The use of disc brakes is almost always limited to mountain bikes. They are most likely not appropriate for a casual rider, but may be beneficial for serious racers or particularly "perforamnce" oriented, serious riders in general. Disc brakes wear quickly, and will need to be replaced often. As such, if you are doing long rides without a lot of technical maneuvers, disc brakes are probably not for you.

There are two kinds of disc brakes. One is mechanical and the other hydrolic. The mechanical system uses all the same cables, housing, and levers as V-Brakes or Calliper brakes. Hydrolic brakes use fluid instead of cables, and require a different skill set for adjustments.

Adjustment

The brake pad nearest the bike's wheel (inner pad) should be as close as possible to the rotar without actually touching it. If it is too far from the rotar, applying the brakes will cause the rotar to bend. This problem occurs becuase only the brake pad farthest from the wheel (outer pad) moves. In order for the brakes to work, the outer pad pushes the rotar until it also touches the inner pad.

Inner pad adjustment

There are two ways:

1. The first is to screw or unscrew the...??? until the pad is properly the adjusted.
2. The second is to slide the frame of the inner brake pad back and forth on the calliper. To do this, unscrew the two bolts that secure it, and mamually adjust its position. Remember to resecure the bolts when you have your desired position.

As the pads wear (they are made of a softer rubber and rherefore wear more quickly than other brake pads), you will need to readjust the position of the inner pad.

If you need to replace disc brake pads, they are manufacturer specific, so you must find pads made by the manufacturer of the caliper. These are the only ones that will fit. This is also good to keep in mind when purchasing disc brakes. To remove the pads from the calliper, you should just need to slide them out. There should be a tabe that you can grab in order to facilitate this process.

Once the pads are properly adjusted, further adjustments are made identically to those use for V-brakes or Caliper brakes.