Construction of the brake.
On a bicycle is braked by exerting a force on the wheel.
This is done by pressing one or more brake shoes which are attached to the front fork or frame against a braking surface of the wheel.
The wheel as a result experiences a great resistance so that the bicycle will slow down.
The size of the braking action is determined by:
- The distance from the braking surface to the axis of the wheel. The greater the distance to the axis, the greater the braking effect.
- The force with which the brake discs are pressed on the brake surface. The greater the force, the greater the braking effect.
- The friction coefficient between the brake disc and brake pad. The larger the coefficient of friction, the greater the braking effect.
The brake can be used with the hub ors with the rim.
The advantage of brakes on the rim is that the force of the brake shoe on the wheel to exercise is low, the wheel is not polluted by the braking and need to be applied no additional braking surface in the wheel.
The side of the rim is suitable as a braking surface.
The disadvantage of rim brakes is that they are vulnerable to rain because the rim is always wet, the tire may become hot during prolonged use.
Hub brakes are insensitive to rain, and the warming of the tire.
The disadvantage is that the brake shoes must exert a very large force on the braking surface, the braking forces are translated through the spokes to the wheel rim, the brake charges the fork heavily, and that a special braking surface has to be made in the hub.
Brakes are mounted on the front fork and chainstay or seatstays.
Rim brakes overload the sheath of the fork less than the hub brakes because they are mounted on the crown piece or close to the crown piece and the braking forces are lower.
The load on the hub brakes on the fork depends on the place where the brake lever is mounted.
The longer the brake lever of the hub brake, the lower the load on the fork sheath.
The load of the fork crown, inside head tube and headset bearings does not dependent on the spot where the brake is mounted on the front fork.