On my commute, I have several hills where my speed usually tops 30 mph, and my highest speed is about 35 mph. For riding in general, my top speed was about 45 mph. My brother reached 50 mph on the same hill, but I'm a wimp and started tapping my brakes. I top 30 mph on downhills during just about every ride around here, but 40 mph is unusual. You need a long, steep hill and favorable winds to top 40 mph, and most hills just aren't long enough around here to do that.