Selfsufficientish.com

I have built many recumbent bikes over my short years on this earth so far and have enjoyed riding and building these projects!
for many years i have thought about making a cycle that a man/woman could pedal generating its own electricity? enough to keep a back up battery charged and fuel the bikes momentum? is it even possible? i have looked everywhere for information regarding this topic and would be very gratefull if anyone could point me towards any good information resources
or has any personal experience with home built recumbents human or electrically assisted?
thank you all in advance from the HAPPY HIPPY TIM!!

timhippy wrote: for many years i have thought about making a cycle that a man/woman could pedal generating its own electricity? enough to keep a back up battery charged and fuel the bikes momentum? is it even possible?

Not quite sure what you're asking, here. You can certainly use a bike to run some sort of generator, which can be used to charge a battery. There are a few designs on the web for static bike-generators, but my back-of-an-envelope calculations indicate that it might be quite hard work to get anything useful from it. We've touched on it in one or two threads elsewhere in the forum, like this one.

Or are you suggesting using the generated electricity to help power the bike while you are riding it? Unfortunately, doing this would end up making things harder for yourself. We cannot make perfectly efficient machines - there are always (and necessarily) mechanical losses due to things like friction; also, no generator is perfectly efficient, nor is a battery very good at storing electricity, and nor is a motor 100% efficient at turning electricity back into work. The immutable rule in physics says you cannot get as much effort out of a system as you put into it.

Pedaling a bike with a generator attached would be harder work than pedaling one without a generator. The extra energy you used to turn the generator would be more than the electrical energy that came out of the generator. This means that converting that electricity back into work to assist with the pedalling will end up being harder work than if you were pedalling a normal bike.

However... It should be possible to use some of the 'free' momentum you get whilst rolling down a hill. It should even be possible to rig up a generator that will operate as a brake would - the effort required to turn the generator being used to slow the bike down. That could be an interesting project, but it would require pretty complicated voltage and current regulation, and my knowledge of electronics is not up to that.