Hi Mike ... hot off the press from Buchanan ... edge of spline to rim centre line = 1 15/16" that's "One and fifteen sixteenths inches". Just wanted to clarify that for you.
Hi James, I am not familiar with 'Buchanan', but thanks.
The wheel builders over here seem to be using 2" for that measurement, Geordie's is different from this, as is mine.
So, not much chance of randomly swapping out a back wheel and having it run true. The back hub position is fixed position of course as it attached to the brake drum and then to the swinging arm, in line with the gearbox sprocket.
All a bit 'hit and miss' from BSA!