Bicycles are used by millions of people around the world, whether to get to work or school, enjoy recreational riding, compete in bicycle races or just travel from one place to another. They might seem simple, but they’re a fascinating combination of physics, mechanics and human skills.

A bicycle has two wheels and is propelled by foot pedals, while steered with handlebars. It’s easy to learn to ride, but it takes practice and a safe environment to become proficient at it. Once you’ve mastered the basic skill, it’s an excellent form of exercise that can be enjoyed for a lifetime.

There are many types of bicycles, each designed for different purposes. The most popular are road bikes, which are lightweight and designed to go fast over paved surfaces. They may also have suspension, which makes them more comfortable to ride over rough roads. Mountain bikes are designed for off-road riding, and they usually have more durable frames and components than road bikes.

The most common bicycle accessory is a bell or horn, which can help you let others know that you’re coming. Many bikers also prefer front and rear lights, which can increase your visibility to other road users. Some bikes are designed with child carrying seats, while others can be fitted with racks for carrying cargo. Some cyclists like to use cycling computers with GPS, which can track your speed and distance traveled.

Most bicycles have a chain that connects the pedals to the rear wheel, but some have belt drives instead of chains. Belt drives are quieter and more durable than chain drive systems, but they require periodic lubrication to keep them working properly.

Road bikes can be made from aluminum or, for higher performance, carbon fiber. When choosing a road bike, consider your needs and budget. If you want to go very fast over paved surfaces, you should choose a carbon-fiber frame, while someone who wants to ride for fitness and fun can be just as happy with an aluminum frame.

Some cities have extensive infrastructure to promote cycling, such as bike paths and velodromes. These facilities tend to be safer for cyclists than conventional roads, since they separate them from motorized traffic. However, such dedicated pathways often have to share their space with in-line skaters, scooters and pedestrians, which can cause conflicts and even collisions. Bicyclists can also develop overuse injuries if they increase the length and frequency of their rides too quickly. Common symptoms include muscle pain and numbness. If you experience these symptoms, it’s important to speak with your doctor. He or she can suggest strategies for safe, effective recovery.