I've averaged 20 mph on my 10.5 mile (flat) commute, one time. I had to really push myself to make that. Normally I average between 15 and 16, from door to door. This includes the many turns and stop signs/lights (I'd say ~20 stop lights/signs).
It's weird though, because I normally have a head wind each direction. Typically, it's a 10 to 15 mph headwind which dramatically slows me down. With an unusually strong headwind, I have averaged as slow as 11 mph. I live and work in a valley, so that probably has something to do with the wind.
Of course, the one 20 mph average day I had I didn't have a head wind.
Last edited by hopperja; 03-02-11 at 12:52 AM.