All these posts are based on the assumption that people eat just enough calories to survive and that they would need to increase intake to pedal a bike around. just one quick look around a mall will tell you that is not the case. almost every american eats more than they expend hence the ever expanding waistline. most people could stand lose quite of bit of potential stored energy in their body (ie fat). fat is 9 kilocalories per gram. that gigam article calculated 2.8kWh per 100 miles which converts to 2,400 kilocalories per 100 miles.
if someone wanted to lose 50 lbs of fat (I'd say most americans need to lose more than 50lbs of fat) that would be 22,679 grams of fat. that equals 204,000 calories which equals 8,500 miles of cycling. (now we understand why its so hard to lose weight)
so basically, without increasing any caloric intake, the average american could fuel 8,500 miles of cycling from their built up reserves. in the process they would feel better, sleep better, have more energy, lower blood pressure, decrease risk of diabetes, reduce cholesterol, increase cardiac efficiency, reduce risk of heart disease, etc etc etc. exercise and weight loss have innumerable health benefits. if you think of the carbon footprint of health care delivery and pharmaceuticals that can be avoided by being healthy, that is staggering.
also, just do a quick google search for "amount of food thrown away in the US" and you will see that somewhere between 30-50 percent of our food is thrown away so its unlikely that an increase in food consumption by the 10 to 20 percent of americans who aren't overweight and are taking in a steady state amount of food is going to change our carbon footprint. if you worry about carbon footprint of human food consumption, you should just convert to becoming a vegetarian.
http://www.nytimes.com/2007/06/06/business/worldbusiness/06iht-greencol07.4.6029437.html
http://planetgreen.discovery.com/food-health/vegetarian-diet-carbon-footprint.html
so comparing e biking to pedal biking in terms of energetic efficiency is probably merely an academic question - in an ideal world where person are finely tuned machines in perfect health that eat a precise amount of food and that is precisely the amount of food we produce, ebiking may have a slight edge. In the real world where people eat more than they need, where food is thrown away, where healthcare expenditures are huge, where most people are overweight, and where most people dont exercise nearly enough, pedaling is far superior.
that being said, i ebike because pedaling 10 miles back home with a 1000 foot elevation gain at the end of the day is tough and ebiking makes it more enjoyable and doable. if i didn't ebike, I would probably just break down and drive. by ebiking, i get a good amount of exercise because I always pedal anyway to assist my motor and I avoid driving.
now driving vs ebiking is a no brainer in the ideal world and in the real world.
