In today's lecture, we're discussing the history of the bicycle. The earliest version, invented in the early 19th century, had no pedals; riders pushed their feet against the ground. By the 1860s, the 'penny-farthing' appeared with a large front wheel, which allowed greater speed but was dangerous. It wasn't until the 1880s that the 'safety bicycle' was introduced, featuring two equal-sized wheels and a chain drive. This design made cycling much safer and more accessible, leading to a boom in popularity among the general public, especially women, who found it liberating.