A bicycle is a human powered land vehicle, also called a pedal cycle, bike, or push bike. It has two wheels attached to a frame, one in front of the other, and a chain connected to cogs on the pedals and rear wheel. The rider, who sits on the top, powers the bicycle by turning the pedals. The word bicycle comes from the prefix “bi,” meaning two, and the suffix “cycle.” Bicycles are used for recreation and transportation.

A specialized type of bicycle is the stationary bicycle, which is typically used in homes and fitness centers for exercise and rehabilitation. Other specialized uses include the transport of goods and people on light commercial vehicles known as cargo bikes, which may have trailers or other attachments. Bicycles can also be used for medical purposes in physical therapy and rehabilitation.

Many bicycles are built with aluminum, steel, or titanium alloy frames and components to keep them light. High-end bikes are often constructed with carbon fiber, which is even lighter. The material is highly versatile and has a high strength-to-weight ratio, which allows designers to make the bicycle both stiff and compliant by manipulating how the materials are assembled and profiled.

The most popular use of the bicycle is for recreation, including leisurely riding and racing. Competitive racing on a bicycle requires a great deal of practice, and many amateur cyclists participate in races to improve their skills. Many countries have national and state championships for cycling, which serve as a way to gauge the abilities of the country’s athletes.

Bicycles are also a common form of transport, especially in countries with limited road infrastructure. In urban areas, they can help to reduce air pollution and traffic congestion by minimizing the need for cars and buses. In addition, bicycles can be parked easily and are inexpensive to operate.

In rural areas, bicycles are sometimes used to move crops from field to market. This type of farming is called subsistence agriculture, and it is increasingly popular in some developing nations. Bicycles can also be used to deliver goods to shops and markets. For example, in some cities, delivery services employ cyclists to carry milk and other food products from the supermarket to the consumer’s home.

A bicycle can be a safe and convenient mode of transportation, particularly for short distances. However, riders must be aware of the risks associated with riding on public roads. The most important thing is to wear a helmet, which can significantly reduce the risk of serious injury or death. Cyclists should also stay alert to other traffic, obey all traffic laws, and ride on the right side of the road. Motorists are often not looking for cyclists and may be surprised to see them on the roadway. They should also allow ample space when passing. In addition, it is important for cyclists to dress in bright clothing and use reflectors on their bikes to make themselves more visible.