Pedal-powered bicycles have been around for centuries, with velocipedes being the first. They are low-slung, aerodynamic bicycles that increase speed and reduce drag. The first pedal-powered velocipede was built in Paris in the early 1860s by Pierre Lallement. He was hired by a carriage maker to make a velocipede.

The first American bicycle craze started late in 1868, and quickly spread to major East Coast cities. It was inspired by news from Paris. In 1876, two British companies were invited to exhibit bicycles at the Philadelphia Centennial Exposition. The bicycles were a copy of the British Duplex Excelsior. The American bicycles were styled to appeal to children, and weighed about 60 pounds.

In the late 1800s, ordinary bicycles were constructed from heavy steel. Their speed was limited by the diameter of the front wheel, which restricted pedaling cadence. To increase speed, the front wheel was increased in diameter. The rider’s pedals connected to the front wheel through the cranks, and power was transferred to the rear wheel through a chain.

The first velocipede was constructed in Paris in the early 1860s, and was called a “velocipede de pedale.” The rider would propel himself by pushing his feet against the ground, which was supported by a frame-mounted pedal-crank. However, pedaling and steering through the front wheel remained a problem. In 1865, the Olivier brothers pedaled a velocipede 800 km from Paris to Marseille. The following year, a pair of Englishmen, J.H. Lawson and his nephew, James Starley, pedaled the same distance.

In the following decades, the bicycle industry shifted from Paris to Coventry, and the bicycle industry in Britain began to decline. Sales were lost in France during World War II, but the British market easily absorbed the entire batch. In the 1920s, the bicycle industry in the United States was displaced by automobiles. This led to a smaller adult bicycle market, which developed during the 1950s and 1960s.

In the 1930s, alloy steels became widely used for frame tubes. This increased the availability of light frames. In the following decade, aluminum became more popular because of its light weight. These frames were primarily used for mid-range bikes, with lighter alloys becoming popular in the following decade.

In the 1960s, the teenage fad was typified by the Schwinn Stingray. This bicycle had a banana-shaped saddle and large handlebars. It accounted for about 75 percent of bicycle sales in the U.S. By 1968, about 20 million teenagers owned high-rise bicycles.

The frame on an adult bicycle is generally made of steel, aluminum alloy, or a composite material. The goal is to have a light weight that is strong. The frame is usually constructed by machine, or by hand with brazing and welding. The frame is composed of a front triangle (top tube, seatstay, and down tube), a rear triangle (chainstays and rear wheel dropouts), and an axle. The axle may be tightened with bolts at the ends or a quick-release skewer.