Triumph's pre-unit twin-cyclinder motorcycles were produced from 1938 to
1962, with engine sizes of 350cc, 500cc and 650cc. Ridden both on the
road and in competition, the bikes formed the basis for Triumph's
success through the 1940s to the 1960s. With iconic names such as Speed
Twin, Tiger 100, Trophy and Bonneville, the pre-unit Triumphs came as
sports bikes and tourers. With their superb styling and reliable
engines, there were a favourite both at home and abroad. Triumph
Pre-Unit Twins looks at the history and development of these bikes, and
describes the various models that make up the range. It gives a detailed
technical analysis of each model. Interviews with past and present
owners give riding impressions of the bikes both today and back in the
1960s.