Great Bikes?

1938 Triumph Speed Twin

There are many reasons why the twin-cylinder engine made such a big impact when it was introduced by Triumph in 1938. Scarcely wider than the equivalent singles it made obsolete, it was a pragmatic solution to the market’s desire for something smoother and more powerful than a single yet less complex by far than multi-cylinder machines.

In addition, the structure of UK vehicle tax which rated on piston area, pushed British designs to smaller, harder working engines. Why go bigger and lazier, as the Americans’ promoted, when the smaller twin was much more efficient?

Even though it still vibrated, the vibrations were less severe than the equivalent, heavier single, due to the shorter stroke, which also allowed higher RPM and, coupled with greater valve area, more power.

In laying the foundations for the post-war boom in the British motorcycling industry, the Triumph twin became an icon that was copied by every other manufacturer of large capacity ‘bikes. Curiously, however, it remained a very British design. The Americans stuck to their V-Twins and the Italians and later, Japanese, went down the multi-cylinder route for road and racing machinery.

The immortal Triumph Twin motor

Despite, and maybe because of, America’s reliance on the V-Twin for its home grown product, it was the American riders who were instrumental in the capacity of the twin rising from 500cc to 650cc and later 750cc to provide the power they demanded both on the road and in competition. This was a shame as, in its 500cc guise the Triumph engine is beautifully smooth and can be tuned to a ridiculous degree. Later, larger versions, whilst having more power and torque, vibrated more. This wasn’t a problem confined solely to Triumph; Norton resorted to rubber mountings for their twin.

Triumph stole a march on their rivals with the introduction of the Speed twin in 1938. The onset of war merely consolidated that lead. The Speed Twin was revolutionary in its engineering; the genius of Edward Turner did the rest. The use of chrome and pinstriped painted panels on the tank and wheels, highly polished chain cases and the Amaranth Red paint finish added up to a machine that was streets ahead of the competition.

It is easy to knock the British motorcycle industry for throwing away the huge market and global lead it had going into the sixties by relying on increasingly antiquated designs. The parallel twin engine, being at the heart of the motorcycle, is also looked upon with derision, especially in the face of massively superior offerings from the Far East.

But, just as the Japanese came along with their own quantum leap in engine design, so it must be seen that Triumph made a similar leap back in 1938 and left us with a legacy of great bikes that is every bit as significant as anything that followed.