Race Radios are being phased out. These are little two way radios racing cyclists use to speak with each other and the team boss in the car behind. They've been used since the early nineties when the American Motorola team used a system provided by their sponsor, which I believe were actually early GSM handsets and not radios per se.
When racing with a radio, you are generally warned slightly ahead of time of exceptionally dangerous circumstances. Except cyclists do this for themselves. We just avoid a danger without thinking about it. However if your focus is draw to the danger, you can become "fixated" on an obstacle you would have simply cycled past before.
Race Radios kill tactics. There is nothing brilliant about putting a strong team drilling it at the front, just so the team leader can jump of the wheel with 3k's to go. For apologists of this school of racing I suggest an equally intellectually challenging sport: http://www.nhra.com/. Unfortunately that is what race radios lead to. Another thing that becomes evident with he lack of radios is the cohesiveness of a team. Most teams find the situation of not being led from the car unbearable, because each is out for themselves.
Often ignored in cycling coverage is the first hour of a race. It's usually in the first hour that a race is "designed" if you will to take a particular out come. This is where the big teams in a race will try and out fox each other, trying to get the other to expend more energy in protecting it's position. For example this can be done by incessant attacking, or a strict marking. With radios a team will just assume control and let a break go or retrieve it depending on who is in it and how much time they have -as seen from a list in the team car. Without radios riders will generally save energy and and use their own position to manipulate circumstances. They will mark one another or mark a break. An intelligent team will know to always be in a dominant position in a break. This team will be covered against most eventualities. and have more cards to play. The drag racers on the other hand have only one card.