Freddy Prince formed The Rotrax company in a cycle shop in the city of Southampton where craftsmen made the famed Rotrax lightweight cycle frames.
It was to be later, in 1952 that Rotrax started to produce their first Rotrax Speedway Motorcycle Frames. Mike Compton, who was the Workshop foreman, together with the British Oxygen Company, developed a nickel-
The early Rotrax frames had a Red badge with RT in white letters on the head stock the same as the cycle frames.
Meanwhile, Alec Jackson (himself a former rider) had taken over manufacturing rights of the JAP speedway engine in 1951 and continued to hand build engines and spares for many years afterwards, later still to be taken over by George Greenwood.
The Rotrax frames were initially chromed by Blakes of Gosport and then sent on to Alec Jackson's in London for the fitting of a JAP engine. And so the Jackson-
The earlier Rotrax Mk1 machines were fitted with 22 inch rear wheel whilst in 1956, this was changed to a 19 inch rear wheel. Former Norwich rider Phil Clarke made many of the Rotrax frames under contract from his workshop in Norfolk.
This evolved in 1969, which included an oil-
Frame: Rotrax design built with Reynolds 531 tubing and low temperature bronze welded throughout. Finished in bright polished chromium plate.
Front Forks: Telescopic type with concealed springs. Fork girders bridged for strength.
Clutch: NORTON type with multiple bonded plates. Chain wheel running on .25" rollers and incorporating rubber shock absorbers. Chain wheel 42T. Final drive sprockets 14T, 15T or 16T
Transmission: Primary Chain: 1/2 x .305 Renold. Final Drive Chain: 5/8 x .255 Renold.
Wheels: Strongly built on steel hubs with heavy gauge spokes and steel nipples. Knock-
Rear Sprockets: Light alloy. Sizes 57T to 60T.
Footrest: Solid one-
Rear Mudguard: Valanced at R.H. side to protect carburettor air intake from dirt.
Tyres:Special Speedway 2.75 x 23 front and 3.50 x 19 rear. Two solid security bolts fitted to rear wheel
With George Greenwood now in charge of producing the JAP Speedway Engine, the final development came about with the introduction of the 84S Four Valve DOHC engine designed by former rider Mike Erskine.
We are indebted to Tony Webb of Binbooks for the above information