StoneRoad2013's photos with the keyword: M20

BSA M20. 126,000 [approx] of these side-valve 650s saw service in WW2 The saddle was remarkably comfortable. en.wikipedia.org/wiki/BSA_M20

Significant contrast in military motorbikes. on the left is a BSA M21 [600cc side-valve] from WW2 [development began in 1937]. The M20 & M21 were some of the most numerous models supplied to the British Army. on the right is an Armstrong MT500, developed in the 1980s. Note then lighter construction and much higher ground clearance.