Although Paul Treen had been experimenting with prototypes for a couple of years already, the first model sold in any quantity was the 1935 model. Even so, production in 1935 was very small, and only perhaps fifty total bikes were produced. Of these, only two are known to exist today. One is in the Smithsonian's Transportation Collection, and the other is privately owned and shown here.

While many features of the 1935 model continued for years, many were changed by 1936. The flat-sided fuel tank had recessed side panels which were welded to the main body of the tank. The seat bar above the fuel tank was installed before the frame was welded together, and thus was not replaceable. Carburetion was by way of a mixing chamber, as the Tillotson carburetor had not been adopted yet. A compression release was fitted to the cylinder head, and consisted of a tube which ran back down to the crankcase. A valve was attached at this point which could be opened to assist in starting and stopping the engine.

English bicycle wheels and brakes were used, as well as Torrington bicycle gooseneck and handlebars.

1935 Engine with Compression Release Valve fitted to crankcase

While the 7/8" tubing used to build the frame was continued for another two years, the 1935 is the only model to have only one vertical support tube under the seat (centered behind the engine). All later models used two vertical uprights on either side. An Eisemann LE-71 magneto was used for spark.

The engine serial number begins with the four digit year designation "1935" followed by the production sequence number.