bicycle: lightweight, two-wheeled, steerable machine propelled by its rider; the bicycle is said to be the most efficient means yet devised to convert human energy into propulsion.
-- The New Encyclopaedia Britannica
A marvel of efficiency, the bicycle is also cheap, handy, nimble. It can sprint like a cat, then stop on a dime and give you nine cents change. It is easy to ride and speedy enough for any sane short-distance traveler. In the typical bumper-to-bumper city creepathon the bike can outrun a Porsche.
Unlike the car, truck and bus, the bike does not spew stinky fumes and carcinogens. A...