page_title: Triumph Speed Twin
section_title: Development
hierarchical_section_title: Triumph Speed Twin / Development
caption_attribution_description: Another classic "mill" from days gone by! This time a single cylinder OHC engine with simple Amal carburettor.
context_page_description: The Speed Twin 5T is a motorcycle that was made by Triumph at their Coventry, and later Meriden factories. Edward Turner, Triumph’s Chief Designer and Managing Director, launched the Triumph Speed Twin at the 1937 National Motorcycle Show. It was a 500 cc OHV vertical twin in a lightweight frame and the first truly successful British parallel twin, setting the standard for many twins to follow. After World War II the Speed Twin was responsible for the survival of Triumph - and every major British marque offered a 500 cc twin designed on similar lines to the Speed Twin.
context_section_description: After the war the recovery of Triumph at Meriden was largely due to the Speed Twin, which was developed in 1946 with telescopic forks and optional sprung hub rear suspension. The headlamp and instrument area was tidied up in 1949 with the Turner-designed nacelle, a feature retained until the end of the model line. In 1953, the Speed Twin caused controversy among traditional British riders as the generator and magneto were replaced with a Lucas alternator and battery/coil ignition system.
  Further development led to the 1959 model 5TA with a unit engine and gearbox construction and styling changes including the unpopular 'Bathtub' fairing which became more and more abbreviated as the model developed before disappearing altogether for the last year of production in 1966.
  The unit 500 engine continued development in the parallel Tiger 100 range ending with the Tiger Daytona models which ceased production in 1973.
caption: The drive side of 1958 Speed Twin engine
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