Bicycles are powered by pedals that turn cranks that rotate a wheel at the back. The bottom bracket and chain hold the cranks in place. Most bicycles have a chain transmission to move the power from the pedals to the rear wheel. A few bicycles also use special belts or shaft drives. Some bicycles also have hydraulic transmissions.

Bicycles have evolved a great deal since the first bicycles were built. While bicycle frames used to be made of heavy steel, they are now made of lightweight alloys. The goal of the materials used to build bicycles is to combine high strength and low weight. For example, since the 1930s, alloy steels have been used in the frame tubes and forks. In the 1980s, aluminum welding techniques made it possible to use aluminum in place of steel. Because of their lightweight characteristics, aluminum alloy frames became popular. Today, most mid-range bikes are primarily made of aluminum alloy. However, more expensive bicycles are often made with carbon fiber. Carbon fibre is lighter than steel, but it has the added benefit of being stiff and compliant.

The modern bicycle has come a long way since the penny-farthing bicycle of the 1870s. Improvements in modern materials and computer-aided design have allowed for the emergence of more specialized designs. These bicycles are essentially similar to their predecessors but have different parts, such as the handlebars, seatposts, and handles.

Women’s bicycles are often constructed with step-through frames. This style of frame is more common on smaller bicycles than in larger ones. The step-through frame is a popular option for those with joint problems or limited flexibility. Although it’s more common in smaller bicycles, the step-through style is also favored by those who want a comfortable ride.

The bicycle was first produced in Britain in 1868. Two British companies exhibited their designs at the Centennial Exposition in Philadelphia in 1876. Then, an industrialist in Boston named Albert E. Pope began importing British ordinary bicycles and making Columbia bicycles, a replica of the British Duplex Excelsior. The wheel diameter and pedaling cadence of an ordinary bicycle limited the speed. Larger wheels increased the speed and made riding on rough roads much easier.

The bicycle’s tires must be properly inflated to ensure safety. Bicycle tires will usually have a marking on their sidewalls to indicate the correct pressure. Bicycle tires are generally made with higher pressures than those used on cars. A car’s tire pressure is in the thirty to forty psi range, while a bicycle’s tire pressure is usually 60 to 100 psi.

The 1860s were an important decade for the bicycle. It was during this time that ball-bearing hubs were invented, as well as metal-spoked wheels and solid rubber tires. The lever-operated four-speed gearshift was also introduced. The 1860s also saw the introduction of the velocipede by James Stanley. Another early modern bicycle was the Penny Farthing, a bicycle that used a large front wheel. During this period, bicycles weighed around 70 pounds and cost around $300.