Just to confirm that I used the method of putting a close fitting filed up piece of aluminium between the left hand bolt and the LH end of the slot for years with total satisfaction. The only drawback for me, was the need to change the packing piece when I changed the outrigger.
When racing, you need to be able to change final gear ratios quickly. I carry three outrigger brackets with 18, 19 and 20 tooth sprockets already fitted to self aligning bearings.
I converted the Enfield rear hub to take an aluminium carrier that then will accept interchangeable aluminium plate sprockets. I mostly use 34 and 35 tooth and this gives me a smaller increment of change. The chain has two split links and I insert one of several different short lengths of chain to make the final length when I change the gearing. In my tool box there were a variety of aluminium packing pieces. It was this need to make ratio changing more efficient that gave me the idea of the snail cam. You are quite correct in that a little time with a file can produce the 3mm clearance needed to fit a snail can and the cam itself is easily produced with a hack saw, a power drill and a file.
I am very conscious that my fascination with making things can carry me away. I love machinery and workshop machinery or motorcycles are just examples of beautiful mechanical logic that we can play with. The snail cam example was put down in case someone like me might enjoy making one themselves. Otherwise they can be made economically on CNC machinery if enough folks were interested. Ok I have rambled on enough when I should be working! Kind Regards Roger
