Good morning, everyone. Today we're going to look at the history of the bicycle. The first bicycle, invented in the early 19th century, had no pedals. Riders pushed their feet against the ground to move forward. This design was called a 'hobby horse'. Later, in the 1860s, pedals were added to the front wheel, creating the 'penny-farthing'. However, this design was dangerous because the front wheel was very large. It wasn't until the 1880s that the 'safety bicycle' with two equal-sized wheels and a chain drive became popular, which is similar to the bicycles we use today.
❓ According to the lecture, what was the main problem with the 'penny-farthing' bicycle?