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Comment by exporectomy | Hacker News Reader

Not the most efficient. Humans have only about 10% efficiency converting food energy to mechanical work. You could burn that food and power a combustion engine to get more work from it. Or burn some other fuel that's easier to get than food, such as wood or, well, oil.

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Bit higher than that:

> The efficiency of human muscle has been measured (in the context of rowing and cycling) at 18% to 26%.

https://en.wikipedia.org/wiki/Muscle#Efficiency

Does that include inefficiencies in digestion?

Yup. From the same section:

> This low efficiency is the result of about 40% efficiency of generating ATP from food energy, losses in converting energy from ATP into mechanical work inside the muscle, and mechanical losses inside the body

Its lucky that a lot of Americans have excess chemical energy stored as fat, just waiting to be converted to mechanical energy with a bicycle.

You failed to take account for the fact that cars are two orders magnitude heavier than bicycles.

Nobody mentioned cars.

This little 125cc motorcycle get 125-150 mpg. Tops out at 55mph.

https://powersports.honda.com/street/minimoto/trail125-abs

A gallon of gas is 31,000 calories according to a quick Google search. I could ride a lot farther with those calories on a bicycle, albeit over more time.

What if we attach a combustion engine to a bicycle?

I can ride 100 miles on a big plate of spaghetti. I have yet to see any kind of vehicle that can do that sort of distance on so few calories. Part of the equation is that modern bikes are quite light and do not add a lot to the total weight.

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