Bicycle

A bicycle is a two-wheeled vehicle that a person powers by pushing pedals with their feet. The rider sits on a seat, holds a steering bar called handlebars, and pushes pedals connected to the back wheel by a chain. Bicycles are one of the most common forms of transportation on Earth. People use them to get to school, to work, to deliver food, to race, and just for fun.

The first bicycle was invented in 1817 by a German man named Karl von Drais. His machine had two wheels and handlebars, but no pedals. Riders pushed it along the ground with their feet, like a giant scooter. Pedals were added in the 1860s. Then came the high-wheel bicycle of the 1870s, which had a huge front wheel as tall as the rider's chest. It was fast but easy to fall off of. The "safety bicycle" of the 1880s gave us the design we still use today: two wheels of equal size, a chain, and air-filled rubber tires.

A bicycle is a brilliant machine because it uses simple parts in clever ways. The pedals and gears act as levers. The wheels turn smoothly on bearings, which cut down on friction. Air-filled tires soften the ride and grip the road. Together, these parts make the bicycle the most energy-efficient way humans have ever found to travel. A person on a bicycle can go three to four times faster than a person walking, while using less energy.

Bicycles changed daily life in big ways. In the late 1800s, they gave many women their first chance to travel on their own without a horse or a chaperone. The American leader Susan B. Anthony said the bicycle had "done more to emancipate women than anything else in the world." Bikes also helped train the first airplane builders. Orville and Wilbur Wright owned a bicycle shop, and the skills they learned there helped them build the first airplane.

Today, more than a billion bicycles are in use around the world. In some cities, like Amsterdam and Copenhagen, more people travel by bike than by car. Cyclists in the Tour de France race more than 2,000 miles in three weeks, climbing mountains taller than any in the eastern United States. Modern e-bikes add a small electric motor to help riders up hills. After more than 200 years, the bicycle is still being reinvented.