Sunbeam motor cycles 1921

1921
SUNBEAMS

Model Range
A third version of the 3½ h.p. model was available along with the 'Standard' and 'Semi-Sporting' models which were little-changed from their 1920 versions. The new 'Sporting Solo T.T. Model' reflected Thomas Corbett de la Hay's Senior T.T. win the previous year.

Cycle Parts
The Marston patented, leaf spring suspension was introduced for the front forks of the 8 h.p. v-twin model to become standard for the range except for the T.T. model which had Marston-made Druid style front forks.

The T.T. model had 'vee' rim brakes with a Ferodo-lined shoe at front and back, whilst other models retained a bicycle style stirrup brake at the front and drum brake at the rear.

Engine and Gearbox
A high compression engine remained available for the Semi-Sporting model, and a higher compression, finely tuned sports engine for the T.T. model.

The T.T. model also had a smaller and lighter three-speed gearbox with 'crash' sliding pinions rather than the constant mesh 'rack and pinion' earlier gearbox. The 'crash' gearbox was to become the standard Sunbeam gearbox.

Sources:
* John Marston Ltd., 1921 'The Sunbeam Motor Cycle' Catalogue.
* Robert Cordon Champ, 1980, 'The Sunbeam Motorcycle'. Haynes Publishing.

1921 catalogue cover

T H E Y E A R ' S M O D E L S : 1 9 2 1
3½ h.p. Standard model	Engine Cylinder capacity: 499cc Bore x stroke: 85mm x 88mm Frame numbers: From 10000 (1920) to 12600 Engine numbers: From 9000 (1920) to 11599 Price: 148 guineas
3½ h.p. Semi-Sporting model - no photo
3½ h.p. Sporting Solo T.T. model	Engine Cylinder capacity: 499cc Bore x stroke: 85mm x 88mm Frame numbers: From 10000 (1920) to 12600 Engine numbers: From 9000 (1920) to 11599 Price: 145 guineas
8 h.p. (996cc) JAP v-twin model	Engine Cylinder capacity: 996cc Bore x stroke: 85mm x 85mm Frame numbers: 83501 up Engine numbers: 72000 up Price: 176 guineas
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