My max speed was 25 years ago. I was in Colorado and decided to ride up to Estes Park on US34. I had intended to try to ride up to the top of Trail Ridge Road but I'm a flatlander and my back was too sore just getting up to Estes Park. I hit 50mph on the descent. There is no way I could pedal. My big gear was 53/13 (and low gear 42/21 - again, a flatlander, and also the reason my back was sore).