When I ordered a hub adapter from C.E., I got a 48 tooth sprocket thinking I'd need lots of power to climb hills in our neighborhood. Truth was, I could crest even the most steep at half throttle or less. And worse, going down the same hills without getting on the brakes a bit would over rev the motor. Yesterday was a beautiful fall day up here, so I thought I'd try the 41 tooth sprocket that came with my kit. I used Jim's sprocket as a template to drill the mounting holes, and had to shorten the chain. It took about an hour, but what a nice difference. I can now cruise at what used to almost be my top speed and still crest any hill without having to pedal. She sounds better too.Seems to hit more evenly with a little bit of a load on it all the time. Any way it was a great way to spend a fall afternoon.