Good morning. Today we're going to look at the history of the bicycle. Now, you might think the bicycle was invented in the 19th century, and you'd be right. But the first design, called the 'dandy horse', appeared in 1817. It had no pedals; riders pushed their feet along the ground. Then, in the 1860s, pedals were added to the front wheel, creating the 'velocipede'. However, it was uncomfortable and difficult to ride. The real breakthrough came in 1885 with the 'safety bicycle', which had a chain drive and two equal-sized wheels. This design became hugely popular and is the basis for modern bicycles.
❓ Vấn đề chính của xe đạp chạy bằng chân (velocipede) là gì?