In today's lecture, we'll discuss the history of the bicycle. The first bicycle, invented in the early 19th century, had no pedals and was pushed along by the rider's feet. Later, in the 1860s, pedals were added to the front wheel, making it faster but also more dangerous. By the 1880s, the 'safety bicycle' with two equal-sized wheels and a chain drive became popular, as it was much safer and easier to ride. This design is essentially what we use today, although modern materials have made bikes lighter and more efficient.