Bicycles are machines that can magnify force and speed, and they are also great for transportation. They use kinetic energy (energy from food) to propel themselves forward and backward. However, bicycles are not made of free energy, as stated by the law of conservation of energy, and they must be refuelled before being used again.
Until the early 1970s, bicycle sales were relatively low, but sales increased 22% in the next few years, with sales reaching nine million in 1971. In 1972, sales jumped to 15 million, with most of that growth coming from adult bicycles. The bicycle industry benefited from highly-placed politicians encouraging the construction of bike lanes and cycle tracks in cities, which led to an increase in bicycle sales.
The bicycle became a symbol of the 1970s eco-activism movement. Its popularity was promoted in media and by individuals. The Bicycle Industry Association published lifestyle advertisements in the press, and many writers wrote best-sellers about cycling. One of these best-selling books was “Richard’s Bicycle Book,” which sold more than a million copies. In addition to promoting the use of bicycles, the book also contributed to the environmental movement.
Bicycles can be divided into two types: road bikes and mountain bikes. Road bikes are made for speed, and their tires are narrow. Road bikes often feature disc brakes for increased safety. They’re ideal for paved surfaces, but they can also be used for fitness riding and long-distance commuting.