Vincent Black Shadow
Vincent Black Shadow

Perhaps the most famous motorcycle photo ever taken is the one of Rollie Free setting a motorcycle land-speed record aboard a Vincent Black Lightning at Bonneville in 1949. Of course, that photo owes as much, if not more, of its fame to the fact that Free was lying on the seat, feet extended straight back in nothing more than swim trunks while traveling at 150.313 mph!

Rollie Free on Vincent Black Lightning
Rollie Free on Vincent Black Lightning

The story of the inspired beginnings of the Vincent big twins in 1936 is told by Vic Willoughby in his book, “Classic Motorcycles” (See our review of his book here). Australian engineer, Phil Irving was sitting at his drafting table with a drawing and a tracing of the timing side of the 500cc high camshaft Vincent single.

“Idly, Irving turned the tracing over on top of the drawing and lined up the centers of the crankshaft pinion and the idler wheel of the timing gear. His brilliant intuition recognized a sudden possibility. ‘Here, look at this,’ he called to Phil Vincent, boss of the outfit. For there, clear as daylight, was a ready-made layout for the timing-side crankcase half of a 1,000cc 47 degree V-twin,” Willoughby explained.

Advertisement

The Series A Rapide was the first version of the big twin produced. It wasn’t long before the big twin was showing its potential for unmatched performance in its day.

Willoughby describes how George Brown, a Vincent factory test rider, took a Rapide to Brooklands for the Motor Cycle magazine Clubman’s Day competition and laid down a 113 mph blast through the kilometer timing traps and set lap speeds just under an average of 106 mph!

While the performance was scintillating, the power behind it was too much for the clutch, layshaft bearings and cases — all of which had to be upgraded.

Vincent Big Twins | History Making Motorcycles
Vincent Big Twin Diagram

After WWII, the Series B made its debut, with beefier transmission and cases and the included angle between the cylinders increased to 50 degrees. Other innovations included elimination of the cradle-style frame and making the engine and transmission, now in unit construction form, a stressed member of the chassis.

The oil tank was eliminated and the large top member of the frame was used in an oil-in-frame configuration. The clutch was given a centrifugally-activated mechanism that increased clutch plate pressure as engine torque increased.

The sporting version Black Shadow and racing version Black Lightning emerged and on Series C bikes the hydraulically damped Girdraulic fork replaced the older friction-damped Brampton fork.

So potent was the Series C V-twin that it even became the weapon of choice for going after land speed records. In July, 1955, in New Zealand, Robbie Burns set a world sidecar record speed at 163.06 mph and Russell Wright pushed the solo record to 185.15 mph.

The final series D bikes went into production in 1955, but with a much more genteel angle to them. The extensively faired Black Knight and Black Prince made elegant high-performance touring bikes, but high prices and low sales brought the Vincent marque to its end in 1956.

Vincent Big Twin Gallery: