In Car Communication

[24Chromium]

You certainly don't need to hardwire. I can't really see any advantage. I've got mine attached to my helmet. The hard part is getting your speaker and mike in the best and most comfortable spot inside your helmet. And getting that right in a passengers helmet is even tougher.

Since this is mainly for your coach, I would assume your coach is instructing and therefore might already have a chatterbox on their helmet. If that is the case (and you've got your own chatterbox), then you simply need a cable that allows two chatterbox modules to be muxed together.