Originally Posted by
Rob_E
I find very little difference in exertion when using or not using a dynamo. So while pedal-power may be inefficient overall, I would be surprised if there was a significant increase in food intake if you were already pedaling. Some days I ride a bike with a generator hub, and some days I ride another bike. I have not noticed myself eating more on the dynamo days.....
Conservation of energy, it's the law. Energy in, energy out, and energy stored in your body. It's all accountable. You can calculate what you need to eat in order to charge those batteries. If you didn't eat it today, you will eat it tomorrow, or you ate it days ago. It aint free.
Think about riding in general. If you ride a decent clip, you burn 500-600 calories per hour. What does that cost? A couple of energy bars (or a Big Mac) might cost ~$3.50. So the cost is not much different than driving and SUV an equivalent distance. And what about the environmental impact? I'm sure driving the SUV is worse, but there is significant environmental impact in producing, packaging, transporting and metabolizing those energy bars. It aint free.