ABC 400cc flat twin

A couple of photos of an ABC flat twin. The ABC was a Granville Bradshaw designed bike that was manufactured by the aero company Sopwith.

A typically Bradshaw design, the ABC was both futuristic and flawed. The bike featured leaf spring rear suspension at a time when most bikes were rigid. The motor was a 400cc ohv flat twin but the valve gear was a notable weakness and several different brands of after-market improved valve gear appeared soon after the bike's introduction. With standard valve gear the bike was notorious for shooting pushrods out on a horizontal plane.

The 400cc ABC was a limited success with the buying public and was made from 1919 to 1923. The demand for a small, expensive and sophisticated machine was limited in a conservative market. The peculiar fact that Bradshaw designed the bike without a kickstart and that it had to be paddled off to start cannot have helped.

The design was licensed out to Gnome et Rhone in France who had a connection with Sopwith as fellow aviation manufacturers. The Gnome et Rhone version received several improvements (strengthened valve gear, a kickstart and a boost to 500cc) but was also not a big seller and made only from 1920 to 1924.

ABC flat twin. The very dropped bars are slightly
incongruous with footboards and legshields.

The ABC was a luxury machine so it is fitting
to see it in the garden of an upmarket house.
A small dog's butt has cheekily crept in to the picture!