Good idea - I think helmet communications between road caption and tail gunner (and others, if possible) makes a big impact on the safety and organization of a group ride.
I've used the
(Cardo Systems) Scala Rider Q2, G4 and G9 units and I think they all work great. They all use Bluetooth for clear communication. (There are other brands that also use Bluetooth but I don't believe any are compatible with any competing brand.)
The
Q2 works best for rider to passenger, or for small groups over a half mile distance. The G4 and
G9 offer a longer distance and can connect up to four people simultaneously. You can check out a
comparison chart here.
