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Triumph Speed Twin 5T

1938 Trumph Speed Twin1939 Triumph Speed Twin 5T1959 Triumph Speed Twin1966 Triumph Speed Twin

The Triumph Speed Twin changed the face of motorcycling. Before it, most motorcycles, sporting or otherwise, were singles. But the Speed Twin was so successful that almost all other factories jumped on the bandwagon with their own versions. Its parallel twin engine configuration was to endure until the demise of Triumph some four decades later.

One man can take most of the responsibility for the Speed Twin - Edward Turned, who had been the man behind Ariel's Square Four. Moving to Triumph, Turner quickly revitalised the firm's 250, 350 and 500cc singles as the Tiger 70, 80 and 90. Good looks and exciting performance suggested by their name ensured the new models' popularity . However, in 1938, Edward Turner brought out the range leader that would really establish Triumph as market leaders.

Turner's new Speed Twin was light and smaller than the Tiger 90, enabling it to slot into the same frame. Weighing 5lb less than the Tiger 90, it cost only £5 more at £75. It had better acceleration, pulled more smoothly and revved more freely, with valve gear many supposed to have been influenced by the sporting Riley cars.

The first Speed Twins had a one piece iron cylinder block with six studs holding the base. This proved a weakness and was soon changed to eight studs. The head was also cast iron. Camshafts in front and behind the crankcase opening drove pushrods between the cylinders, operating the valve gear in separate alloy boxes bolted to the cylinder head. Ignition and lighting were by a Lucas Magdyno behind the cylinders and lubrication was by double-plunger pump. Transmission was by a separate four-speed gearbox. The appealing finish was Amaranth red and chrome with gold lining, the engine was good for around 90mph. In 1939 the factory produced a sports model, the Tiger 100. Finished in black instead of red, this model would top 100mph. Fitted with a supercharger, it took the Brooklands 500cc lap record to over 118mph.

Had it not been for the war, which interrupted production, the trend-setting Speed Twin might have dominated the market even sooner. As it was, it ushered in a period during the 1950s when BSA, Norton and a host of marques such as Royal Enfield and Ariel all followed Triumph down a parallel twin route.