Average speed is useless. Internet posts all lie about average speed (except speed in races, but that's in a race with a pack, which is very different). I bet that the "22 mph" commuter took his "average" speed by looking at his computer while riding with a tailwind or on a slight downhill, or both.

Hills make more of a difference than you think. I've done races that had a 10 mph average speed because they were all up hill.

If you want to race, forget average speed and internet lies and read this: http://www.bikeforums.net/showthread...s-a-tip-or-two