Harvey Sachs wrote:
"A last note? If memory serves, and I don't feel like checking it myself, the dish of the S/A 3-slot sprockets is about right for spacing a pair of cogs, if they are mounted back-to-back. Might be worth checking. For less bad shifting, that solution would probably require grinding off the tops of the pointed cogs before doing real riding".
Some years ago, I bought a Granby with a Sturmey AW which had two sprockets back-to-back, and a pre-war Cyclo "Oppy" derailleur. That combo shifted perfectly, without the points ground off the sprockets, so it may not be essential to grind them off. It may not be so critical when using two sprockets, and indeed, Cyclo and Trivelox's pre-war two- and three-speed freewheels had pointed teeth, and worked fine. Perhaps it becomes more critical as the number of sprockets on a freewheel increases, with the chain having to work at more of an angle?
Weymouth, Dorset, England