The fastest I've seen professional riders go in the Tour de France is 110 kmph (68 mph) down a long 12% grade in the Alps. They were riding on their top tubes to get more aero and, of course, were on aero bikes. 75.7 mph is 122 kmph. I find it hard to believe that you were going 10% faster than any professional rider can go. I'm going to have to go with Cyccommute on the computer error.