I have been using bike-to-bike communications for years. I started with citizen's band radio (CB). This has worked fairly well, and has decent range, provided your antenna is properly trimmed. But this year, after some research, I decided to try a blue tooth headset.
Historically BT headsets, such as the Cardo Scala Rider, have worked on a "chain" of pairings for a group of people. That is headset 1 pairs to headset 2, headset 2 pairs to headset 3, and so on. It is important for bikes to ride in line in order of pairing. Then the chain is complete from front to back. But the drawback has been that if a bike in the middle drops out, then the chain is broken, and the front of the line is no longer in communication with the back of the line.
Cardo, among others, have introduced what they call "dynamic mesh communication", or DMC. With DMC a group is established by a creator. Members can be added to the DMC group. And each headset is capable of connecting with multiple DMC groups. Each group can have up to 15 members joined in. The wonderful thing about DMC is that it does not matter the order riders appear in the line, all connect to each other through a mesh network. This provides for up to 1600 meters (1 mile) under ideal conditions, and about 1000 meters in more typical conditions. As long as ANY two distant riders are within this range, they serve to relay the traffic of the entire group. This means the entire group may be spread apart as far as 5 miles, and keep in range. Unfortunately, cross-brand mesh is not supported. Each day, when units are powered on, they remember, and as the headsets are turned on, people join in, and no additional setup is needed.
A group of us have the Cardo Packtalk Bold with JBL sound. In our recent trip to Sturgis it was invaluable for safety and convenience. Anyone in the group can speak, and it is heard by everyone. Also, much different than CB is that multiple people can talk at the same time. In a situation like someone in the back admiring a roadside view and describing it can be interrupted by someone in the front warning of a road hazard that everyone should know about.
But when the rubber hits the pavement, what are the downsides? For the most part these all worked fairly well together. We find at times a very few headsets seem to have a constant rush of air over the microphone, and the one person kindly dropped off so the rest in the group could continue to communicate. But most have no issue with this. We are still trying to figure this out. Also, in a truly torrential downpour one of the headsets mic went dead, but was still operating otherwise, even though the maker advertises these are relatively rain proof. That headset came back to life after a bit.
The other wonderful thing about these is that many of the functions of the unit can be controlled by voice command; "Hey Cardo, Music On", "Hey Cardo, Volume Up", "Hey Cardo, Radio On". That's right, besides being able to pair to a blue tooth music player, Cardo has a built in FM radio receiver. "Hey Cardo, Next Station". "Hey Cardo, Next Track" (for MP3 player).
But besides the DMC network, when in that mode, Cardo can ALSO pair with up to two blue tooth devices. For me I have my phone on one, and my MP3 player on the other. But if you have a free blue tooth channel, you can pair in another older blue tooth headset, and bring that person into the group, provided you stay in range with that blue tooth headset.
Cardo has really thought this out. The software is upgrade-able via the Android style USB plug, which is normally used for charging. And by the way, power draw is minimal, and may last you a few full days of riding between charges (13 hours).
The JBL speaker option is great.Unlike CB, you can hear so very plainly, that you can always tell who you are talking to.
When paired with a phone, you can hear your phone ring, and have the option to "Ignore" or "Answer" the incoming call. Plus, you can add a speed dial, to place calls via voice commands. Additionally, for rider and passenger, if set up in advance, you can even establish a private communication mode, and switch between it, and the group.
How about, "OK Siri, Nearest Gas", or "OK Google, Food Nearby", (depending upon your pair phone type) and by voice you can ask for information you may need while going down the road.
The Automatic Volume feature works great. It is almost never too loud, nor too soft. A roller on the side of the unit makes it simple and easy to adjust volume while going down the road.
Audio sharing is another feature we did not use, but it allows any rider to share their music, whether from the pair MP3, or the built in FM radio, or even a phone call.
Charge while you ride, if you have a USB port anywhere nearby. And their is a phone app to allow you to very simply control all of the options and features of the device.
Installation was fairly quick and simple, with no tools required.
Blue tooth has come a very long way. Good communication in a group ride can save a LOT of frustration, and add safety to your travel. These units are not cheap, but they can be purchased as one, or two headset units. It is my personal opinion they are well worth the price of admission, and helped keep us all a bit safer on our recent trip to South Dakota.