Today's lecture is about the history of the bicycle. The first bicycle, called the draisine, was invented in 1817 by a German baron. It had no pedals, so riders pushed their feet against the ground. Later, in the 1860s, pedals were added to the front wheel, but this design was unstable. Then, in 1885, the 'safety bicycle' was introduced with a chain drive and two equal-sized wheels, which made riding much safer. This design became popular quickly. Interestingly, the modern bicycle we know today is not very different from that 1885 model, except for materials and gears.