Recommendations forDIN adaptors to USB connectors; also wired versions:  

It is not easy to find these; especially for good reliable ones with plugs that do not release from vibration, etc….and at a reasonable price. I tested the following products for temperature, output, regulation, ETC.  Price is reasonable.  These connect to your motorcycles electrical system, either to the battery, or to the system after the ignition switch, or simply plug into an existing DIN jack (or, one you add) on your motorcycle.  These adaptors I recommend are NOT cheap cigarette lighter socket plugs but quality Hella-DIN types, that grip well into your socket.  All have 5 volt USB type outputs. Single and dual versions, either with 2.1 or 3.3 ampere ratings for output.