Arthur Davidson and William Harley developed their first motorcycle in 1901 by attaching a two-horsepower engine to a bicycle frame. They sold three motorcycles that year. In 1907, Harley-Davidson developed a reputation for winning motorcycle races. During World War I and II, Harley-Davidson produced thousands of motorcycles for the US military. The company struggled in the 1980s but has since set new production records, especially in the early 2000s.