Introduced for 1959, the Triumph Bonneville T120 was a twin-carburettor, 650cc parallel twin developed from the Tiger T110. Its name celebrated Triumph-powered speed-record achievements at Utah’s Bonneville Salt Flats. Fast, stylish and particularly popular in America, it became one of the defining British motorcycles of the 1960s.
The 1966 T120R Roadster pictured here used a 649cc air-cooled, overhead-valve parallel twin, with a 71mm × 82mm bore and stroke and twin Amal Monobloc carburettors. Unit construction placed the engine and four-speed gearbox in a common assembly, while lubrication used a separate oil tank. Gear changing was by the right foot, with an eight-inch front drum brake and seven-inch rear drum providing the stopping power. The purple-and-white 1967 T120R retained this traditional 650cc layout.
The blue 1977 T140V shows how the Bonneville developed through the following decade. Its 744cc parallel twin was paired with a five-speed gearbox and left-foot gear change. The oil-in-frame chassis carried its engine oil inside the main frame tube, replacing the separate tank, and hydraulic disc brakes were fitted at both ends. These changes brought the familiar British twin closer to contemporary expectations while retaining its distinctive character.
The Bonneville also proved itself on the racetrack. In 1969, Malcolm Uphill won the Isle of Man Production TT aboard one, recording the first 100mph lap by a production motorcycle. Meriden production continued through the workers’ co-operative years until the factory closed in 1983. The name returned with a new Hinckley-built model unveiled in 2000 for the 2001 model year.
