Surely you line up the end of the rod with the hub in middle gear to get the correct position in old school SA 3 speed?If you get it right but have to undo to fix a puncture. You’ll find the correct position is the line between dirty and clean threads
There is usually a window in the Axel nut and a line on the linkage that should appear there in the middle gear. That’s if old school sturmey archery.
I think there is a window visible, arrowedSurely you line up the end of the rod with the hub in middle gear to get the correct position in old school SA 3 speed?
Not expressed that very well but there should be a window in the AXLE nut to see the position. The nut the OP refers to is just a lock nut to secure the correct setting.
The one with the big pink arrow pointing at itThe OP I think is referring to the locking nut for the chain/cable connection.