With the BikeCharge Dynamo Bicycle USB Charger you have an ultimate solution, by converting your pedaling into electric power to juice up your devices. he BikeCharge Dynamo is powerful, efficient, light weight, compact, and easy to install. It fits most spoked wheels, it can charge any USB powered devices and it is waterproof. It has built-in 1000mAh Li-ion battery to power lights and provide steady power for charging smartphones and other devices. The BikeCharge Dynamo fully charges most mobile phones with 2-3 hours ride.