the fastest overall average i've mustered for my 14 mile commute is 19 mph. and that was with a really nice tailwind, hitting all of the greens on the 3 super-long lights along my route, and really, really exerting myself. to get up to a 20 mph overall average, i'd have to find a way to shave 2 entire minutes off of my fastest ever time, and i just don't think that's possible for me along my given route, even if everything goes right.