Very good but in my time of using this kit I have found some problems with it, first the chain witch comes with the kit could be a better quality chain since it ended up getting so lose that it felt like it was going to come off and eventually ended up snapping 3 links in it. One other issue I have noticed are the crank arms witch you can purchase with this kit as they could be stronger because I have managed to bend the crack arms twice now whilst riding. A way around this might be to get slightly short cranks as I fell that they are a little to long since you'll find that you can easily tap the ground. Apart from this they are defiantly the best kit out there at the moment and are quite easy to install on your bike. Even with these things I have noticed I wouldn't think twice about recommending to someone else.
The gear ratio means your legs go round a thousand times to move a centimetre. Totally pointless. If you run out of power you could actually cycle the bike home. So when would you actually use these?
It is true propelling the Sur-Ron and any speed with pedals is not an option with a standard setup, you would need to use a much smaller small sprocket on the rear (OEM kit uses a 25T) and even then it is not going to be a rideable option. The kit is designed for mountain bikers who prefer the feel of pedals the propulsion add on it for US laws which state that the pedals must be capable of propelling the bike (naturally no minimum speed is required ) For us Europeans the propulsion add-on has the added benifit if giving feedback on the pedals.