Dr SPROCKET

 

 

                               

 

Almost every Triumph chop i've had with a fat 16" rear wheel has the chain rubbing on the tyre or runs the rear wheel offset to one side making the bike ride like a bendy bus.
Take a standard knackered gearbox sprocket, cut the teeth off then turn it down to fit inside a suitable piece of tube and machine the centre out of another sprocket to fit over the tube. Fasten it to the bike and slide it until the chain line is as required, cut the tube to length then weld it up (or in my case get someone who can weld properly to weld it up). Bottom pic is an 18t we did for Old Blu' last time, going for a 20t this time for "tourability"