I would recommend FRS/GMRS radios for bike-to-bike. I would suggest just running on FRS frequencies where everyone is legal. From a handheld radio, you won't get much more than an extra mile of range from the extra power of typical GMRS handhelds. I have gotten more range and much more pleasing results out of FRS/GMRS than from CB. There is simply too much noise on CB and the antennas that you would want to mount on a motorcycle are not efficient. I would suggest spending time performing a reliable install that will allow solid communications out to a mile or two with radios and using a cell phone for the few times when you get farther separated from the other rider.
I have had CB base stations, mobiles, and the optional CB unit for my GL1800 Gold Wing. I could only turn the modulation up to about 60% on the Gold Wing CB which further limited it's effective range to a little over a mile between two same equipped Wings.
You can expect a consistent 2 miles from FRS/GMRS. Don't expect anywhere near the advertised claims. You would only get the 10 miles or greater range on a good day if two bikes were parked on the peaks of two mountains and had line of sight between them.
The antenna on an FRS radio is relatively efficient especially compared to a rubber duck on a handheld CB but also compared to a loaded CB mobile whip mounted on the bike with it's minimum ground plane.
My riding buddies think of me as the "radio guy" when it comes time to rig up our bikes for a trip. I have an Advanced Class Amateur Radio License, but have not been active for a couple of years. I also have an 180 feet tower with my own business repeater. I have installed Chatterbox, J&M, and a few others I can't think of the name of. I prefer Autocom products over all others that I have experience with. The thing I want is a complete Bluetooth wireless system to do away with the "rat's nest" of wires.
Mount your helmet speakers as close to your ears as possible or comfortable. Mount your microphone as close to the front of your mouth as possible or comfortable. If you have a cell phone and bike-to-bike radio both hooked to an intercom system, mount them on opposite sides of the handlebars. You sometimes have injected noise that is solved by running off the internal batteries of the radio instead of being powered from the bike.
Enforcing the FCC requirement for a license to operate GMRS became overwhelming when GMRS radios became widely available in shrink-wrap packages to the general public.
A Radio Operators Permit was required when I received my pilot's license in 1978. The FAA has since cancelled that requirement for domestic flights. To my surprise though, a Radio Operators Permit was listed as a requirement a few years ago when I flew our Archer to the Bahamas and then again last year when I flew our Maule to the Cayman Islands, panel shown below on our way home.
