Today's lecture is about the history of the bicycle. Although early prototypes appeared in the 19th century, the modern bicycle with pedals and a chain was developed in the 1880s. This design, known as the 'safety bicycle', became popular because it was much safer than the earlier 'penny-farthing', which had a very large front wheel. Interestingly, the safety bicycle also played a key role in the women's liberation movement, as it gave women greater personal mobility. By the early 20th century, bicycles had become a common means of transport in many cities.