Get this Kinesis K3 Wind & Solar 3-in-1 mobile device charger on Tanga for $29.99  plus $2.99 shipping (list is $100).  So if you were riding your bike on a cloudy day, you’d still have charging capability!

The Kinesis K3 features three charging capabilities in its multi-functional design: wind, solar or AC wall plug. An ideal charging component that works for iPods, iPhones, music players, smartphones or PDAs, portable gaming devices, GPS units, cameras, Bluetooth devices and more; the USB port is built into the device for adapter tips to charge various gadgets.