Despite its thoroughly British reputation, Triumph was founded as a bicycle manufacturer in Coventry in1897 by Siegfried Bettmann and Maurice Schulte as an extension of their bicycle business in Nuremberg, Germany. Triumph first produced bicycles and the first motorcycle – with 220cc Minerva engine – appeared in 1902. JAP and Fafnir engines were used until Shulte designed his own single-cylinder, four-stroke, side-valve engine in 499cc and 547cc capacities.

By 1908 the British company was firmly established, Jack Marshall winning the single-cylinder TT race on the Isle of Man that year. A small (225cc) two-stroke machine called the Baby was a success, whilst the Ricardo designed ‘Riccy’ 499cc, four-stroke, ohv four-valve, of the early ‘20’s established Triumph as a performance range.

Close co-operation with the German Triumph factory on a range of models continued for many years: the final split did not come until 1929. Although the German factory finally closed in 1957, the British made Triumph continued, and the company’s current hand-built, large capacity, machines remain much in demand worldwide.


The side valve 5.5hp SD (spring drive) uses the same basic engine that gave excellent service in dispatch riders machines during The First World War. Announced at the 1923 Motorcycle show as a new model for 1924, its specification was a great improvement on predecessors. It features a chain rather than belt drive – the first time on a Triumph – plus an efficient engine shock absorber, the primary chain and clutch enclosed in an oil bath chain-case, a three speed gearbox and a front wheel internally expanding brake.

Many features of the SD were shared with the much more famous 1923, 499cc. OHV, four-valve Triumph ‘Riccy’.

The exhibit is finished to represent a dispatch rider’s motorcycle and carries the service badge of the 21st Armoured Group on the petrol tank. It is in full working condition and was donated to the Collection in August 1968 by Jill Jones.


Manufacturer: Triumph Motorcycles, Meriden, Coventry. England
Model: Type SD
Engine: Single cylinder 550cc side valve
Top Speed: 50 mph
Price new: £66.50 (£66.10s.0d)