I've had a 3-spline driver on my ASC so long that I'm not sure where the 12-spline one is. Like decades. I suspect that Hilary is right that the 12-spline is rounder, but compared to the out-of-round of good cranks of the era and the inherent back-lash of the hub, that hasn't been a factor for me. On the other hand, being able to quickly change the sprocket is nice, allowing me (in theory) to use the wheel with various bikes - and ruefully compensate for increasing age. I haven't used it yet, but I did put aside a 22 cog for some years from now. :-(
harvey sachs mcLean va usa ++++++++++++++++++++++++++++++++++++++ For my ASC auction I will swap out free of charge the 12-spline driver for a more modern 3-spline driver which will take modern and easily available sprockets. And I can supply the necessary driver for anyone with easy to follow instructions who wishes to replace a 12-spline driver in an ASC, AM, AF, AC, FM or FC with a 3-spline one. However the the 12-spline sprockets are better made than the 3-spline ones and are rounder so more satisfactory in a fixed gear system. I used a 4-speed SA control with an ASC (using positions 1, 2 & 4) very satisfactorily on a daily basis throughout the 1980s - instructions are on the web for converting a 4-speed trigger to the ASC type - this gives you a faithful copy of the ASC trigger as regarding cable pull.
Hilary Stone, Bristol, England
Doug Smith wrote:
>> Members,
>> SA. ASC. on ebay:-
>> Just a thought for any prospective buyer/bidders proposed purchase.
>> I would pose the question regarding the future replacement of the 12
>> small notched sprockets and lock nuts of the ASC hub. I understand
>> they are quite rare to obtain if at all! Perhaps a couple of spares, if
>> available, from the seller would a good idea. In my experience this
>> model does need the correct 3 speed changing gear control to work
>> effectively.
>>
>> Doug Smith
>> North Dorset
>> UK