Today's lecture is about the history of the bicycle. Although early prototypes appeared in the 19th century, the first commercially successful design was the penny-farthing, introduced in the 1870s. It had a large front wheel and a small rear wheel, which made it fast but dangerous. By the 1880s, the safety bicycle, with two equal-sized wheels and a chain drive, became popular because it was much safer and easier to ride. Interestingly, this design also encouraged more women to take up cycling, as it allowed them to wear practical clothing. The pneumatic tire, invented later, greatly improved comfort and speed.