Well... I'm still breaking the motor in... only 2 tanks so far. The NuVinci hub is great, but it is not shift-on-the-fly.... it has 3 "steps" or gear ranges and you must let off the throttle to change up or down... not a big deal, but I wasn't made aware of that until I bought it. With a 20 tooth gear on the hub... the motor currently does not have the power to get above 34-35 mph (it was advertised to be able to pull up to 45mph). I weigh 220, and the bike is a mid-grade aluminum Diamondback with full suspension and disc brakes... so if your my size I would definitely go with the GXH50. I am going to change to an 18 tooth gear on the gearbox so the motor will be able to "pull" into it's power range in "3rd" on the NuVinci hub... top speed will be about 33-35 but the mtor will be able to use all 3 gears on the hub... currently with it's power level and the mass it has to pull it can't reallly make use of the top gear. Maybe it will do better in the future - the motor is supposed to gain about 25-27% horsepower after a break-in period of 6 tanks... so still waiting. I hope that info helps... overall I like the setup... but I had expected a higher quailty kit ( as far a the switches, bolts - etc) and much better instructions and manuals (no Honda manual - had to get online) from Staton... for me their customer service was flaky and slow. Hope that heps - Chris
