BSA WM20 should the center of the wheel rim be in the center of the down frame tube .
I am going by the gearbox plates , running a straight edge along them to the wheel rim , look to be about 10mm diffrence
Wheel rime is about 35mm away from frame one side and 65mm the other !
With the wheel in the frame, the center of the rim should be in line with the center of the frame.
The rear rim offset measurement is:- with a straight edge across the face of the hub where the brake drum bolts should be around 10mm to the rim or about 44mm to the center of the rim. Ron
Thanks Ron
I refitted the gearbox to check sprocket aliment , moving the wheel so it does , I have just over 40mm on the side tube , so I am happy with that !