My 10 mile commute takes about an hour on my commuter bike, and I can do it in about 50 minutes on my road bike in lighter traffic on weekends. That isn't very fast, but I'm also riding through Manhattan. When I was in better shape a few years ago I averaged 21.2 MPH doing loops in Prospect Park, over 15 miles without any stops (that's the best thing about riding Prospect Park, you NEVER have to stop.) That was an all out solo effort for me, and nobody else in the park was keeping up with me except for the real racers, not the wannabees. I was in my early 50s at the time so I'm not so young anymore either. The park has one hill up and on hill down, and since it is a closed loop, the net climb is zero. To do 21mph on a 10+ mile commute is just impossible if you ask me unless you have an uninterrupted trail door to door.

The absolute fastest I ever rode was my 4.25 hour century. That's 23.5mph. This was NOT excluding stop time as there wasn't any. It did include the slower start to the ride in Seattle, but once on the open road the pack just flew. The only problem was that it was a double century, Seattle to Portland, and I had to be peeled off the ground to do the second 100 miles. I did it in about 10 hours total which I still think is damn good and again this was total time start to finish, no exclusions. This was when I was still in my late 20s.

Tomorrow I'm going to commute on my carbon fiber road bike. I'll see if it makes a difference when I'm riding in the heavier weekday traffic. At least the stretch through the park and over the bridge will be faster.