When Harley-Davidson rejected the idea, Treen decided to enter the market himself and designed his Servi-Cycle.

Paul Treen would often visit the factory's tool shop and work with the engineers on new ideas himself, resulting in continuous improvements to Simplex products instead of annual new model introductions.

[1] Simplex's minimalist philosophy was maintained throughout the company's history, whose designs changed little after 1935.

[6] A 1935 Simplex Servi-Cycle motorcycle is currently on display in the Smithsonian Institution's America on the Move exhibit.

[11] The Servi-Cycle used a magneto of Simplex's own design, providing 6 volt electricity for the dual ignition and for the headlight, taillight and stoplight.