My mistake - I should be more careful and check the sources instead of relying on my memory. The changeover on some models occurred in 1951 whilst with the top end models was delayed to 1952 or 53. This is certainly confirmed by the NOS hubs I have had through my hands over the years ASC and FC hubs seem to be the last to move to the three spline driver. I have had them dated as late as 1953 with the three spline driver. Regards Hilary
Sheldon Brown wrote in response to Hilary Stone:>
> I have occasionally seen the 12 spline type on very old hubs, but I
> believe the changeover to the 3-spline type happened well before
> 1957. Indeed, my '52 ASC uses a 3-splined sprocket, and I've seen
> lots of late 40's hubs with these. I've paid attention to this for a
> long time, as I used to be diligently hunting for the older threaded
> drivers for use with hybrid gearing (I've gotten as many as 7
> sprockets onto S-A hubs this way.)
>
> Pre-war S-A hubs are extremely rare in the U.S. British bikes were
> mostly unknown here until returninv veterans started bringing them
> home aftwer WWII
> Hilary Stone wrote:
>>Sturmey Archer's hubs in the 1940s and 1950s used two types of sprocket -
>>screw-on mostly on their basic AW and AB, FWs, etc and a 12 spline sprocket
>>on their upmarket hubs FM, FC, ASC, AC etc. This was also used on their
>>pre-war 2-speed fixed hubs TF, TFB, T and TC, and the 3-speed KS and KSW
>>hubs. The familiar 3 spline sprockets were fitted from 1957 onwards right
>>across the range of hubs. But the pre-war hubs can only use the 12 spline
>>pattern - this isn't strictly true as the 3-spline sprockets can be
>>modifified just a little with a Dremel and fit on the 12 spline drivers.
>>Post war hubs can have their drivers changed for later 3 spline drivers and
>>that is a very simple operation.