Simply using a thinner snap ring will allow a third sprocket to be fitted to the stock 1/2 speed or BWR hub!  Stock snap ring is 2.0mm and the replacement needs to be 1.6mm.  This allows you to then use a combination of sprockets such as 12-14-17 making a 2 speed ratio a lot more usable or a 6 speed even wider!
​ You can simply use a friction shifter or other shifters may work depending on the set up. It is common to need to modify the cable run, with an inner cable going straight through the spring of the anchorage and fastened with a barrel nut / grub screw.
- Without modification to the rear frame sprocket sizes are limited 19t on a steel triangle and 18t on a Ti triangle 
To purchase 1.6mm snap rings, click here and email me!