20 mph average for a commute is difficult to achieve. My highest average for a 16 mile one-way commute on my road bike with no extra gear was 19.4 on MUPs and roads without lights. That meant cruising at 22-24 mph for close to an hour with slowdowns only for turning, bad sections, road crossings, transitions from MUP to road, and the like.
Last edited by alan s; 03-02-11 at 08:24 AM.