My commute is 17 miles each way over flat central Florida terrain split about equally between neighborhood streets, busy roadways and a nice trail. My cruising speed is typically between 15-18MPH. With the traffic lights and stop signs during rush hour, I typically average a little over 12MPH over the entire distance. Interestingly, when I started riding about 10 years ago, my top cruising speed was more like 12-13MPH and my average was still right at 12MPH.