Since I'm using a motor driven, bicycle chain drive, pedal power, coaster brake, rear wheel/ hub adaptor sprocket...whew, on a Simplex (kinda) frame thought I'd post some pictures and explanations.
The rear wheel is driven by two sprockets a twenty tooth 3/16" on the right side provides power from the bicycle pedals. There is a 44 tooth 1/2" sprocket on the left, mounted on a hub adaptor for motor power. Braking is coaster brake operated by back pedaling the pedal crank. 1901 thru 1920 most moto-bicycles used a similar arrangement...even the V-twins of Harley, Indian, Pope, Excelsior etc. all based on a bicycle frame and forks. Worked pretty well despite massive engine weight, little or no suspension, often absent front brakes ,pitiful tire compounds & horrific roadways. Think about the board track racers of the era who raced & often died at speeds over 100mph on those simple macines.
The photos show a cartridge type bearing & shaft along with the "bracket shell" which houses it, threaded left & right to accept the cartridge to which the crank pedals will be attached. The "shell" will be welded to the Simplex frame on a plate which will also accept the "drive off" kickstand, behind the engine/trans case.
The pedals only turn under human power and can help power the bike with engine running or not. The pedals/chain also act as the linkage to the rear coaster brake and if the right side chain breaks the rear is brakeless. Simple system that I trust when aided by a good disc/caliper arraingement up front. Rick C.