When you get into a car accident, you always say you were going slower than you actually were. When you get into a bike accident, you always say you were going faster than you actually were :)
I ride a lot and have gone 45-50 mph down hill, a big hill and it freaks me out every time since my field a vision narrows and I know that if i hit a pot hole, a pebble, a snake or a black bear that I am a dead man.