The earliest bicycles had no brakes. For bikes to become popular, an effective mechanism for slowing and stopping had to be devised. That is how brakes came into existence; they increased the frictional force on the wheels enabling the rider to slow down or stop. Steering was another important requirement if the cyclist had to negotiate steep turns without falling off. Over the decades, handlebars and braking materials may have changed, but the fundamentals of steering and controlling a bicycle have not changed.
The first widely used braking system was known as the plunger. It first appeared on the high-wheeled bicycles of 1800. The principle of the plunger was simple. For slowing down a bicycle, a lever was either pressed down or pulled up. This made a metal shoe to press against the outer side of a tire creating friction. The drawback of this system was excess wear and tear on the tire. It did not work with pneumatic tire as well, even after covering the metal shoe with rubber. The performance of the plunger was also poor on wet surfaces as water decreased the friction between the brake shoe and tire, reducing the braking power.
The coaster brakes were another major development. They are still in wide use, especially in less sophisticated bicycles like cruisers and utility bicycles. These brakes are also used in some children’s tricycles and bicycles. They work by reversing the motion of the pedals. The brake mechanism is inside the hub of the wheel and pushes outward on the hub creating friction and slowing down the bike. The brake is quite strong and tends to lock up or skid the rear wheel when engaged.
The caliper rim brake, however, is the most popular brake for road and mountain bikes. Pulling a lever, which in turn pulls a cable, forcing the brake pads/shoes to press against the inner rim of the front/rear wheel, stops the bike.
Caliper brakes are light and relatively inexpensive. However, they have their own set of problems, the most important being their efficiency during rainy season. When wet they take double the time to stop the bicycle. This is because water reduces the friction between the brakes and the wheel. The caliper brakes work best when the cyclist applies gentle pressure.
It is important to balance the braking between front and rear brakes while riding to avoid going over the handle bar due to momentum of body inertia, when front wheel is braked hard to stop the bicycle.