I have the 8fun kit with the motor fitted to a 700C rim.
The kit with the original controller moved along nicely on throttle to 15mph (depending on conditions). Throttle plus pedaling got me to 17/18 mph comfortably.
I changed the controller (got the more recent controller from 8fun with the narrower pedelec sensor and the small led dashboard) and the throttle speed dropped off noticeably (13/14mph) but the pedelec sensor seemed to have a bit more power. Unfortunately that controller burned out and I decided to try an ecrazyman controller.
When I finally managed to fit the ecrazyman controller (thanks to previous posts on this forum
) I noticed a marked increase in grunt. So much so that I have to be careful taking off - the power kicks in very shortly after starting to pedal. This is a bit scary in traffic. With the new controller I get to 18/19 mph comfortably (no throttle fitted so thats with easy enough pedaling). Apart from the increased speed there is a definite increase in power going up hills - I'd say maybe 2mph - its hard to be accurate.
The downside of the ecrazyman set up is that my battery is almost flat after each leg of my 15 mile commute to work. But I have a charger in work as well so each journey is started with a full charge.
Hopefully both the controller and battery will continue to work well together (I've had to replace the battery under warranty 4 times and from the above you can see I'm on my third controller). This current set up is a bit of fun though and I'd like to enjoy it for awhile
John