The company considers 1903 to be its year of founding, though the Harley-Davidson enterprise could be considered to have started in 1901 when William S. Harley, age 21, drew up plans for a small engine that displaced 7.07 cubic inches and had four-inch flywheels. The engine was designed for use in a regular pedal-bicycle frame.
Over the next two years Harley and his boyhood friend Arthur Davidson labored on their motor-bicycle using the northside machine shop 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.
Work was immediately begun on a new and improved machine. This first “true” Harley-Davidson motorcycle had a bigger engine of 24.74 cubic inches with 9-3/4 inch flywheels weighing 28 pounds.
The prototype of the new improved loop-frame model was assembled in a 10 by 15 foot shed in the Davidson family backyard and was functional by 8 September 1904 when it was entered in a Milwaukee motorcycle race, the first known appearance of a Harley-Davidson motorcycle.
In January 1905 small advertisements were placed in the “Automobile and Cycle Trade Journal” that offered bare Harley-Davidson engines to the do-it-yourself trade. By April, complete motorcycles were in production on a very limited basis. In 1905 no more than a dozen machines were built in the backyard shed.
In 1906 Harley and the Davidsons built their first factory on Chestnut Street – This location remains the Motor Company’s corporate headquarters today. The first Juneau Avenue plant was a modest 40 by 60 foot single-story wooden structure. That year around 50 motorcycles were produced.