 From 1953 it had a single downtube swinging-arm frame.From 1959 it used the Rex McCandless designed Featherbed frame, with upgrades featuring an improved AMC gearbox, revised cylinder head, crankshaft-mounted Lucas RM15 60-watt alternator with coil ignition and an 8-inch front brake with full width hubs front and rear.The wideline Featherbed-framed bike was road tested in "The Motor Cycle" 4 June 1959 issue and was reported to have a mean top speed of 82 mph with petrol consumption of 56 mpg at 60 mph.