This bike may look all of a piece, but in reality it's a mongrel. A beautiful mongrel, but still a collection of parts that should have no right to co-exist together; well they do, and bloody well at that.
This bike has had a chequered life, starting out as a 1928 Soyer a French marque that produced motorcycles between 1920 and 1935. Like many French makes of the time, Soyer used a variety of engines for their motorcycles, including JAP, Sturmey-Archer and Chaise. This particular Soyer 07S had a JAP engine but the frame was wrecked, so Barrois built his own frame - and eventually replaced the JAP motor with the 500cc Rudge twin unit you see here.
All unnecessary parts have been removed to make it lighter, including the front brake, and a new 1/4 gallon petrol tank has been added, along with an innovative 'suicide knee' gear shift. Since these pictures wer taken, two small mudguards have been added, and the tyres have been changed for modern high-speed Avons.
Incidentally, the photos are from Guerry & Prat who are experts at providing beautiful photos of unusual motorcycles. They've just launched an exhibition in association with Nick Clements (of Mensfile fame) in Toulouse, which would definitely be worth a trip if you’re in Europe. Find out more details of the Rudge build from here.