It was the German inventor Karl von Drais who developed the first bicycle - the “swift walker” -- in 1817. This bicycle lacked pedals and people “walked” on them. It had a wooden frame supported by two wooden wheels with iron rims and covered by leather. Since then the bicycles have come a long way both in terms of frames and materials used to make them.
In the late 1800s, a tubular steel frame replaced the wooden or cast iron frame. Although the steel bicycles were very strong they were also difficult to handle because of their weight. Even today steel is the preferred material though new age materials like aluminum, titanium and carbon fiber are also being used to make high-end and specialized bicycles.
It is important to consider the properties of the material before using it to design a bike. The properties that are given importance are the yield strength, ultimate strength and elasticity of the material. The alloy that has the three properties in the right ratio is the ideal metal to design bicycles.
It has been found that steel has higher ultimate strength making it less dangerous for the rider in case of a crash. Steel is also the more cost effective, well known and researched material available, and ha been used to make a great variety of tubes and frames. Today, thin tubes are being made to decrease the weight considerably.
Aluminum is very popular for designing because of its low weight. A major drawback of using this metal is the high probability of bending. This is because of its very high yield strength. That is why large diameter tubing is used to lower the chances of bending.
Titanium is the material of choice. It has a natural sheen attached to it and requires very little maintenance. But it is very expensive, and bicycles made of titanium can only be bought by the rich. It has a great strength-to-weight ratio, and regains its shape even after a collision.
Another material is carbon fiber, also called a boat builder’s material. With carbon you can literally change the direction of fiber according to the load bearing areas. The carbon fiber is extremely expensive, and makes it out of reach for all but a few wealthy or the fanatic racers.
The most popular frame design is the diamond or double triangle, which has changed very little since the invention of the safety bicycle in the 1880s. Some frame builders are experimenting with new variations of this classic design. For example, some carbon fiber frames are now made with oval tubing making the bicycle more aerodynamic. Also, new full-suspension bikes have altered the diamond design to allow for mounting a shock absorber on the seat stem.