Disc Brakes - Mountain Bike Zen
Mountain Bike Disc Brakes
Disc brakes are often the brake of choice for mtb riders, however cheap disc brakes will not be better than good V brakes, so if budget is an issue it is better to get a bike with a good set of V brakes rather than compromise and get a second rate disc set.
Disc brakes work the same way as V brakes, you pull the lever and the pads tighten to stop the wheel from moving. With V brakes the pads apply pressure directly to the rim of the wheel. This can actually allow for a more subtle braking that is more difficult to achieve with disc brakes. The disc brakes have a special disc that the pads grip onto to slow the wheel movement down.
If you are upgrading your V brakes to disc brakes you need to check first that your frame, forks and wheel have the correct fittings to attach the brakes to, not all frames and forks are compatible with disc brakes. You can usually buy attachments that will adapt your fittings but your wheel must have a flange with six holes in a hexagonal pattern to be able to fit the brake disc to. If not you will need a new wheel.
First thing to do here is remove the V brakes and cap the bosses, you may be able to reuse the cable from your v brakes if it is in good condition. If not remove the cable from the lever and set it aside with the old v brake mechanism. Then you need to mount your disc brake caliper onto the frame fittings using the bolts that should have been supplied with the brakeset. Once this is fitted you need to attach the cable, if using new cable you will need to cut this down to size. Fit one end to your lever and then measure the cable from the lever to the caliper along the bike where it will travel and allow a small amount extra for adjustments. Cut the cable to size and fit the cable sleeve, it is a good idea to lube the cable before doing this.
Once you have cut the cable down to size and sleeved it, attach the other end to the caliper and adjust the pad travel using the adjuster knobs.
If you are using a hydraulic system the process is a little more complex. If the brake system comes sealed you may be able to simply fit this but you will have to make do with the cable lengths as supplied which may be a little longer than you need. You cannot just cut these down easily as you will need to bleed the brake cables with brake fluid and reseal the cable fittings properly. This may be best done by your LBS (local bike shop). If air gets into your braking system your brakes will not work properly. Hydraulic brakes will need bleeding from time to time to maintain proper efficiency.