I commute to work by bike, sometimes I share the journey with a co-worker. The problem is because of the wind and distance between the bikes, it's very hard to hear what the other person says.
It would be great to have some kind of hands-free radio headset to communicate while riding. For example, one solution might be a bluetooth headset, like the ones used with mobile phones, coupled with some kind of mobile phone or radio.
The best I could find were wired units meant for two people sharing one motorbike. The radio based units I found were again for motorbikes and also seemed very expensive.
Do units like this exist for cyclists?