Brakes
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[edit] Brakes
For trials today, there are two types of brakes, Rim brakes and Disc brakes. Within these categories of brakes there are two further categories, cable brakes and hydraulic brakes.
[edit] Brake types
[edit] Rim Brakes
Rim brakes are brakes that use rubbery brake pads directly on the surface of the rim, this is what you will find on the rear of most generic mountain bikes, as well as on trials bikes. They work by compressing against the rim from both sides, causing friction on the rim and making it decelerate. This can be controlled by pulling the brake lever less or more depending on whether you want to stop slower or quicker. One disadvantage with rim brakes is that any disturbance to the surface of the rim will mean that the brake will have more effect in some areas then in others.
[edit] Examples of rim brakes
[edit] Disc Brakes
Disc brakes work on the same principle as rim brakes, two pads either side compress on the disc, stopping the wheel. However a disc brake uses a disc, connected to the hub (central point of the wheel). An advantage of this is that discs don't generally come under as much strain as rims so, and so it is less likely to get damaged. Also even if the rim becomes damaged the brake will still function. Disadvantages to disc brakes are that they can put a lot of stress on the wheel and frame
[edit] Brake methods of action
[edit] Cable Brakes
Cable brakes use a length of cable, coming from the lever usually to a set of calipers. When the lever is pulled the cable is pulled as well eventually ending in the pads compressing the rim. The most powerful and most popular mechanical disc brake at the moment is the Avid BB7.
[edit] Hydraulic Brakes
Instead of cable, hydraulic brakes use hosing filled with a liquid. At the lever end, there is a piston, which when the lever is pulled, pushes further into the hose. This means the liquid in the hosing is forced towards the other end of the brake. At this end the fluid being forced down means that the pads get forced away from their calipers. This, in turn, means the pads make contact with the rim, which in turn stops the bike.
