The term "recovery" is too vague. There are numerous systems in the body that needs to be rebuilt and replenished. Actual muscle-tissue that's damaged and needing repair is small in volume. Look at the monthly lean-muscle mass gain of pro body-builders and you'll see a slow rate of muscle building. About 100-125gm of protein is the most they need to eat daily. If you just want to rebuild muscle to its original size and weight, then you'll need less than that.
The other more important part of "recovery" is to replenish the glycogen stores in the muscles. This is re-supplied through sucking glucose from the bloodstream. Without sufficient glucose in the bloodstream within 30-minutes of a ride, your body will actually disassemble perfectly good muscle tissue to restore the glycogen supply; it's converting muscle-protein into glucose and using that to build up the glycogen. That's why long-distance riders and pros actually have to do weight-training
during the season, because long-distances completely deplete your glycogen and it's inevitable that some good muscle is catabolized during the ride itself and for enery-replenishment. The weight-training is required just to
maintain a constant muscle-mass. So, it's vitally important to suck down 300-700 calories of carbs immediately after a ride to re-supply your muscles with glycogen, then a normal meal within a couple hours. The 4:1 carb-protein mix appears to have a stronger effect in getting stuff pumped through the cell walls and rebuilding glycogen supplies inside the muscles.
EDIT: Here's an article that goes over history and various components in energy drinks during and after exercise:
Cutting-Edge Muscle Fueling. The cited journal articles are very good sources to follow up as well.
