The Dahon BioLogic ReeCharge is the green way to go when charging your iPhone. Using a lithium polymer battery that can charge by wall outlet, USB, but in the case of the ReeCharge, a bicycle that contains a hub dynamo.
You start off by attaching your BioLogic ReeCharge to your bike, which captures and stores the green energy created by magnets in your hub, which in turn powers your iPhone. This is great when using certain iPhone apps that drain your battery. If your caught in bad weather, the ReeCharge comes with a splash proof silicone case and sealed connectors for protection.
Once charging your phone is complete, you can simply detach the BioLogic ReeCharge and you have power on reserve.
One of the best factors, you can use the ReeCharge with any chargeable gadgets, since it comes with a USB cable and five of the most common interchangeable tips for devices. Retail price is $119.95.