Today's lecture is about the history of the bicycle. Early bicycles, called velocipedes, appeared in the early 19th century. They had wooden frames and no pedals; riders pushed their feet along the ground. In the 1870s, the penny-farthing was introduced, with a large front wheel and a small rear wheel. It was fast but difficult to ride safely. Then, in 1885, the safety bicycle was invented, featuring two equal-sized wheels and a chain drive. This design made cycling much more stable and popular among ordinary people. By the early 20th century, bicycles became a major means of transport.