A bicycle is a human-powered, two-wheeled machine that uses momentum, force and friction to enable riders to travel long distances. It is also a popular form of recreation and exercise, as well as an efficient means of transportation in urban areas. The bicycle was invented in the 19th century and has since become an integral part of the world’s transport systems, with more than 1 billion people worldwide now owning one.

The modern bicycle is a complex machine consisting of a frame, wheels, a seat, handlebars and a crank. The crank connects to the pedals, which are connected to the rear wheel by a chain. The pedals are connected to the crank by a system of gears, which allow the cyclist to vary the amount of power applied to the wheel. The front wheel is connected to the frame by a fork, which allows the rider to steer the bicycle.

There are several different types of bicycles, ranging from children’s toys to high-performance racing machines. The International Organization for Standardization has a special technical committee for cycles (TC149), which sets standards in the areas of terminology, testing methods and requirements for performance and safety.

Bicycling is a healthy and inexpensive mode of transport. It is an excellent way to get exercise, and it can help to reduce the risk of heart disease, stroke, high blood pressure, depression, and obesity. It can also be used for recreational and competitive riding, as a means of transporting goods or for courier services, and as a form of artistic expression.

A bicycle can be fitted with various accessories, such as baskets for carrying groceries, a rack to carry luggage, and a rear carrier or trailer to carry children or cargo. Many families use bikes as a practical, environmentally friendly and cost-efficient method of transporting small children between home and school and around the neighborhood.

Cycling has been shown to improve muscle strength and flexibility, enhance cardiovascular endurance and lung capacity, and decrease the incidence of high blood pressure, coronary heart disease, and type 2 diabetes. It is a great way to reduce stress and enjoy the outdoors, and it can also bring family members together for a fun and social activity.

Every cyclist has a unique set of needs and expectations when selecting and using a bicycle. Reviews of bicycles can differ widely, and some reviewers may be prone to the “honeymoon effect” or have a personal bias that clouds their evaluation. For example, a bicycle that feels fast and responsive to one rider will feel slow and unresponsive to another, depending on their experience level at the time of the review and the types of bike rides they usually take. It is important for potential buyers to pay attention to the reviewer’s experience and expectations to determine the validity of a bicycle review. The more experienced a reviewer is, the more likely they are to evaluate a bike’s components and features accurately.