Staton R/S gearbox kit, Nuvinci, Schlumpf and trike add up to some serious bucks.
I have used the Schlumpf two speed for years. They are super durable and work great! I have a speed drive, high speed drive and a mtn. drive but I bought them long ago when the prices were alot lower. Here is a link to Florian's site, Swiss machining at its best. http://www.schlumpf.ch/ Also check out his hydraulic water pump!