The 1922 Olympia Show.
J.D. (Stand 74.)
Super Motorised Bicycle.
1¼ H.P. Model.
51x57 mm. (116 c.c); single cyl. two-stroke; petroil lubrication; Vici carburetter; chain-driven mag.; single-speed: clutch, no kick-starter: chain-cum-friction drive; 26x1¾in. tyres. Price: Solo, £35.
Bowden Wire, Ltd., Willesden Junction, N.W.10.
Although the J.D. machine is essentially a motor-assisted bicycle, nevertheless it is designed as a whole, not as an attachment to be fitted to ah ordinary bicycle strengthened for the purpose. The engine is particularly well made, the manufacturers assuming that with so small a cubic capacity the power unit would be doing high duty for the greater part of its time, and, therefore, needs to be made better than would be the case with a larger engine.
Power is transmitted from the crankshaft to reduction gearing, and thence to a pulley composed of special friction material engaging with what appears at first sight to be a belt pulley attached to the rear wheel spokes. This pulley can be disengaged by a control on the handle-bar when a clutch action is desired, and is held in position by coil spring mechanism acting through a bell crank lever in such a manner that irregularities in the driven rim have no effect upon the drive.
Those who desire to test the efficiency of the friction drive and understand its operation should inspect the working models on the stand driven by electric motors.
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