This is a really nicely engineered piece of kit. It was easy to fit, and I find cycling with it is much easier. The optional brake sensors that come with the kit aren't really necessary, given that the motor stops as soon as you start pedalling. I bought the 50 mile battery kit, but I don't see that the battery would ever give 50 miles unless the pedal assistance was at it's lowest all of the time. Generally, the battery indicator is down to about halfway after around 12 miles (and I rarely go above halfway up the Pedal Assistance levels). I haven't attempted to run it flat yet, though. Generally, a worthwhile buy, and recommended