In 1901, William S. Harley drew up plans for a small engine with a displacement of 7.07 cubic inches (116 cc) and four-inch (102 mm) flywheels designed for use in a regular pedal-bicycle frame. Over the next two years, he and his childhood friend Arthur Davidson worked on their motor-bicycle using the northside Milwaukee machine shop at the home of their friend Henry Melk. It was finished in 1903 with the help of Arthur's brother Walter Davidson.