The BSA C12 was a British pre-unit

motorcycle A motorcycle (motorbike, bike; uni (if one-wheeled); trike (if three-wheeled); quad (if four-wheeled)) is a lightweight private 1-to-2 passenger personal motor vehicle Steering, steered by a Motorcycle handlebar, handlebar from a saddle-style ...

manufactured by the

Birmingham Small Arms Company The Birmingham Small Arms Company Limited (BSA) was a major British industrial combine, a group of businesses manufacturing military and sporting firearms; bicycles; motorcycles; cars; buses and bodies; steel; iron castings; hand tool, hand, po ...

from 1956 to 1958. The C12 used the same engine as the earlier C11G with the four-speed gearbox, but in a more modern chassis featuring a swinging arm rear suspension. Minor engine modifications meant it was also far more reliable.

References

C12 Single-cylinder motorcycles Motorcycles introduced in 1956 {{Motorcycle-stub