Beginningbr br Clockwise from top left: William S. Harley, William A. Davidson, Walter Davidson, Sr., Arthur Davidsonbr In 1901, William S. Harley, age 21, drew up plans for a small engine with a displacement of 7.07 cubic inches (116 cc) and four-inch (102 mm) flywheels. The engine was designed for use in a regular pedal-bicycle frame. Over the next two years, Harley and his childhood friend Arthur Davidson labored 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. Upon completion, the boys found their power-cycle unable to conquer Milwaukee's modest hills without pedal assistance. Will Harley and the Davidsons quickly wrote off their first motor-bicycle as a valuable learning experiment.