Originally Posted by
Johno59
When mounting the shifter (especially 4 speed) don't fasten the shifter on a curved section of the handlebars, choose a straight section. A curved base buckles the receiver plates and the pawls inside trigger mech can jump off their cams.
I don't think I've ever mounted the shifter on a straight portion of the bar, putting it a bit further away from the grip is a better location for ease of use. I generally tighten the screw down just enough so the shifter won't rotate and I've never had an issue with the shifter bending/failing. I've been riding/working on Sturmey equipped bikes since 1985 or so.