The Vincent Rapide was a motorcycle designed and built at the Vincent works in Great North Road, Stevenage, Hertfordshire UK during the war and released to the press before end of hostilities. The prototype was the Series A 47.5° V-twin launched in 1936. With 6.8:1 compression, it produced 45 bhp (34 kW). It is often purported that Phil Irving was trying to find a replacement for the 500 cc Vincent Comet engine. There were two blueprints on his desk, and one had fallen on top of the other, to demonstrate a "V" formation. There is no evidence to prove this, however. Its frame incorporated the first cantilever rear suspension, used on all subsequent Vincents. Other innovations included a foot gearchange instead of a hand-operated gearlever, a four-speed gearbox instead of two or three and a side stand.
The high power meant that the gearbox and clutch did not cope well and it was developed into the ‘Series B’ which had internal oil pipes and the gearbox integrated with the engine casting (Unit Construction). The angle between the cylinders was increased to 50° instead of the 47.5° of the Series A engine, which allowed the use of the engine as part of the frame. The Rapide had ‘’Girdraulic’’ front forks and triangulated rear springing to prevent front end twist under hard braking. and the cantilever rear became the most widely used form of rear suspension for motorcycles after 1980. Brakes were dual 7-inch (180 mm) single-leading shoe (SLS), front and rear.
A more modern hydraulic shock absorber and spring assembly later replaced the old twin springs and friction damper. The rear seat was supported by a sub-frame down to the rear frame pivot point, providing a semi-sprung seat with 6 inches (150 mm) of suspension.
The Series B had a Feridax Dunlopillo Dualseat, and a tool tray under the front. The Series "B" also had an inline felt oil filter instead of the metal gauze of the Series "A".
Vincent used quickly detachable wheels, making wheel and tyre changes easier. The rear wheel was reversible, and different size rear sprockets could be fitted for quick final-drive ratio changes. The brake & gear shift were adjustable for reach to suit individual feet and the rear mud guard was hinged to facilitate the removal of the rear wheel.
The letters HRD were discontinued in 1950. Vincent were trying to enter the American market, and did not want any confusion with Harley-Davidson (H-D). Falling sales of expensive motorcycles caused closure in 1956. Vincent refused to compromise on quality, which, unfortunately, kept the price up. It has often been said that the firm was guilty of "over engineering". One comment made about this was that "Vincent is a solution in search of a problem."
Legend has it that Irving accidentally placed a wrong side up tracing of the Vincent 500 motor on top of an equally sized drawing of the same motor in such a manner that it formed a V Twin. Moving it so that it would fit resulted in the 47.5° V twin which appeared in 1936. (The single leaned forward 23.75°.)
With 6.8:1 compression, it produced 45 bhp (34 kW).
The Vincent V-twin motorcycle incorporated a number of new and innovative ideas, some of which were more successful than others.
The Vincent HRD Series A Rapide was introduced in October 1936. Its frame incorporated motorcycling's first "cantilever" rear suspension, which was used on all Vincents produced from 1936 through 1955. Other innovations included foot gearchange instead of hand-operated gearlever, a four-speed gearbox instead of two or three, and a side stand.
Pneumatic forks were not to be a Vincent innovation, with both Phils believing girder forks were superior at the time. The Series-A had external oil lines and a separate gearbox.
The 998 cc Series A Rapide Vincent cost $600, produced 45 hp (34 kW), and was capable of 110 miles per hour.
The high horsepower meant that the gearbox and clutch did not cope well.