Managed 48 mph down the backside of a couple of the mountains in Colorado last year (Wolf Creek & Slumgullion passes). Was very nice. All one needed to do to slow down was to sit up and use the wind as a brake. This brought the speed down to 33-34 mph. Never was able to hit 50 mph, but 48 seemed pretty fast. Biggest problem was the wind made my eyes water at this speed. Definitely want to have good vision when flying down the mountain. Great Fun!