Sounds like a bad idea to me. Far too likely to get tangled up in the steering. I'd more likely route a perm cable from a cig lighter under the seat and make a cap for the usb/microusb either from an old female socket or some Sugru. A guy did this a little while ago though, I'll find his post.
Opinions are like A**holes, Everyone has one. Some people seem to have more than one though which is a bit odd.