Downhill mountain bikes generally have disc brakes, which have many advantages and a few disadvantages over rim brakes.
The main advantage with disc brakes is their distance to the ground. Sitting close to the axle, they are less susceptible to picking up dirt, mud, and other debris. These particles can lodge themselves in between the pads and braking surface, decreasing braking power. The disc itself contains many holes, allowing debris to escape which provides a cleaner contact with the pad. With a rim brake, the wheel serves a dual purpose, to hold the tire in place and provide a braking surface. A disc brake, serving a single purpose, which is to stop the bike, can be made with a harder material than would otherwise be possible.
|disc brakes||rim brakes|
Disadvantages are that disc brakes are heavier than their rim counterparts, and the breaking force transmitted from the disc to the rim travels through the wheel spokes. This adds stress to the wheel assembly.
Singletracks » MTB Review: 2011 Avid X0 Hydraulic Disc Brakes – The brake pads on the X0 brakes are top-loading which means you don’t have to remove the wheel to replace the pads. This might seem like a minor detail but it could come in handy during a race like last year’s Fools Gold 100 where competitors burned through multiple sets of brake pads due to gritty and wet conditions. …
Dirty Dog MTB Brake Rotor Review – Josh rolls into the trailhead parking lot, five minutes early for the weekly group ride. Almost everyone else is already there, putting bikes together and doing standard pre-ride maintenance. Matt is already pedaling around …