As Marten noted, it is possible to mount any two dished Sturmey 3-slot cogs on a 3-slot driver, just do it back-to-back.
In turn, you can run darned near any early derailleur back there, although you might need to use a couple of thin washers to increase the spacing between the roller holders, to handle the 1/8" chain.
I've also found that the 3-slot "drivers" are perfect replacements for the original treaded and 12-slot drivers, at least for the ASC hub.
BUT, with standard S/A cogs, I would expect the shifting across the external cogs to be pretty cruddy unless you grind off the tips like more modern cogs on FW. Like 60s stuff.
Your mileage may vary, of course.
I have seen 3 cogs on a threaded driver, but it was a long time ago. I think those were part of a factory Cyclo conversion kit that included the derailleur, shift lever, and cable set.
harvey sachs mcLean va usa.
+++++++++++++++++++++++++++++++ Daniel Artley wrote:
>> I recently found a Sturmey FW at Cirque (Thanks so much to Charlie Young) >> and am awaiting the servicing of this fine hub. I was interested in how >> it might be combined with other fifties shifting systems for my 1953 >> Carlton, so that I might experiment with early gearing. I've been >> fascinated with a two speed freewheel for the Sturmey hub, but don't know >> much about them. Would someone please post, either on or off list how the >> cogs may be mounted to the 3 pin cogged hubshell of a Sturmey Archer hub? >> And what combinations, brand, etc. that worked for this period setup? And >> finally, would anyone have one of these freewheels for sale?
You can mount two cogs on any three pronged SA hub. Brompton still does this to halve the gaps in the wide ratio's, or use any two offset cogs mounted back to back
4 speed conversions involved fitting a special driver which accepted -I believe- screw on cogs.
No need for an extra freewheel btw, the one in the hub is sufficient
-- mvg Marten Gerritsen Kiel Windeweer Netherlands