How it charges is via a dynamo that is attached to the front or rear fork of your bicycle, which is then connected to the charging unit, which is then linked to a mobile device holder than can be mounted on your bicycle’s handle bar. Basically as you pedal, power is generated which is then sent to the charging unit and charges your device. The only downside is that you would need to provide your own charging cable to hook up to the charging unit, such as a micro USB charger or Apple’s 30-pin dock connector.
As to how much it can charge, well according to Thanko, this contraption is capable of producing a maximum of 500mA, but since its power output is entirely dependent on how fast you pedal, it has been calculated that you would need to be going about 20kmph or more to achieve 500mA. If this sounds like something you’d be interested in as a way of keeping your battery topped up, or keeping your device alive until you reach home, Thanko is selling it for ¥1,980 which is about $26.