I was searching on a site called DVice and I saw a post written on bikes that can run off of a battery and a motor.

These GreenWheel bikes are to be less expensive around a few hundred dollars then most of these kinds of things on market these days. This bike is affordable and you can recharge the battery when it runs out. Running on straight electric power the bike takes you around 20 miles of pedal free riding.  You can double the amount of pedaling along with the bike.

The bike isn’t out yet but it should be out soon and affordable also. I think this GreenWheel bike is a really good idea because it’s not only affordable but you’re still getting exercise when you use this bike. You can recharge the battery whenever it needs to be recharged and you can still ride you’re bike with no cost and its cheap and worth it too. You can also help the environment if you buy this bike.  To get this bike you only need to take off your wheel and put a GreenWheel on. Everything is on the tire except for the throttle. Inside the GreenWheel sits an electric motor, batteries and an electric generator. By this spring The GreenWheel team hopes to have more than a dozen different GreenWheel configurations out for riders. 

All though this bike will be out soon you can keep your bike and just take the back wheel off and just put on shorter spokes and you won’t need a new bike. It’s cheap and it’s easy.