The bicycle is said to be the most energy-efficient means of transportation. Where does the energy that drives it come from?

The energy that drives the bicycle comes

from the food that the rider eats.

Well the food that the person eats powers the mucles and the person uses their wieght/gravity to push down on the pedals which pulls the chain and, since the wheel is a diffarent size, you either get more power and less speed or more speed and less power