In A convenient lie, I asserted that a hypothetical 60-MPG car requires enough energy every hour to take a bicyclist 1250 miles. I gave some indication of my reasoning there. I also mentioned that ”precision is not required when the comparisons span orders of magnitude.”
I’m having second thoughts about that last assertion, or at least with its premise that the differences are enormous. Yes, bikes are far more energy efficient than cars, but depending on how you conduct the analysis, the difference may not be as gross as I’ve assumed in positing that mass scale, heavy, high-energy personal transit is inherently non-sustainable without greater-than-real-time solar energy inputs (i.e., without fossil fuels).
Over the years I’ve heard MPG-equivalent figures for bicycles ranging from >2,000 to just barely over 100 MPG. The degree of variability comes mainly from how you account for the fuel requirements to produce and distribute food. Food, that old Malthusian bugbear under the rug of cheap oil, might be waking up as we run out.
It’s beyond my analytical competence (or enthusiasm) to sort out the conflicting estimates to pronounce a winner. But among the more interesting documents I’ve perused recently is a life-cycle analysis that puts the energy efficiency of electrically assisted bicycles 2-4 times ahead of purely human-powered ones, unless the cyclist eats only home-grown food — then it’s closer to a draw.
Off you go, math-heads! I have some bicycle motor kits to assemble: