Nah. In highschool, we calculated HP by timing how fast we could climb a flight of stairs. Using a formula that also took our weight into account, we could calculate how much power was exerted. Basically, X mass lifted Y distance in Z time. We could then calculate HP.

One bigger guy (approaching or exceeding 200 lbs) was over 1 HP. I was somewhere in the 0.7 range.

Mind you, this is full-throttle exertion compete-with-your-classmates numbers, so you'll probably be be pushing way less than that on an average commute. Still, 1/2 HP it entirely reasonable, you could even say 3/4 HP I think!