I weigh 230 lbs, and live in New Mexico. On the flat, I can barely get the bike up to 75 mph at full throttle, but the altitude here is over 5000 ft. I am sure the altitude has an effect on the speed, but a smaller rider might get somewhat better performance. I trailered my motorcycle up to Rocky Mountain National Park, rode up over 11,800 elevation. On the ride I found at higher rpmĀ“s the engine intermittently sputters above 8,000 feet altitude. By leaning the fuel ratio slightly on high altiude rides corrected the problem.