Depends, but my avg could be between 16 - 20 mph, and as I get in better shape I'm sure it could get up to 22 or 23. When I was in my teens and early twenties, I used to push to get a high avg speed over a certain distance. Now I just ride for time and have certain training goals on my ride. Avg speed is now more of a "afterthought," except when I'm timing myself on a course I've done over and over.