I'd say, based on the time it takes me to make trips of a known distance, about 12 mph average (and most of my trips are 3 miles or less around town). This is on a hybrid with 700x38 tires in a rather hilly area, with the occasional stop at an intersection etc. Sometimes more like 10 mph with a headwind (ugh) or on particularly hilly routes. In other words, I'm not exactly a speed demon. Hopefully as I continue to ride more it will improve some; it would be interesting to see what my average speed would be on a longer trip.