Braking & Steering |
A closer look at the subject. ©1997 The Exploratorium |
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Brakes have improved as materials and engineering know-how have evolved. The earliest bicycles lacked brakes, which added to their daredevil reputation. For bikes to become more popular an effective mechanism for slowing and stopping had to be devised. All brakes, regardless of the mechanism, share one thing in common--they increase the amount of friction (usually on the wheel) allowing the rider to slow or stop. Steering a bicycle has remained a constant. While handlebars have evolved, the fundamentals of steering and controlling a bicycle haven't changed. But recently our understanding of the science behind steering a bicycle has.
Take the Plunge The first widely used braking system was know as the plunger. It first appeared on the high-wheelers of the 1800s. The principle of the plunger brake is simple: by pressing down or pulling up on lever, a metal shoe is pressed against the outside of a tire creating friction and slowing the bicycle down. The problems with this system include excess wear on the tire (it doesn't work well with pneumatic tires, even when the metal shoe is covered with rubber) and poor performance on wet surfaces. Water decreases the friction between the brake shoe and the tire, lessening the braking power. Coaster Brake The coaster brake is still in wide use throughout the world and appears in a number of less sophisticated bicycles like cruisers and utility bicycles. Coaster brakes also appear on some children's bicycles and tricycles. The coaster brake works by reversing the motion on the pedals. The brake mechanism is inside the hub of the wheel and pushes outward on the hub, creating friction and slowing the bike. This brake is particularly strong and tends to "lock up" or skid the rear wheel when engaged. |
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