Check out www.hammernutrition.com. They have 2 main sports drinks. One is their HEED which doesn't have protein. It is designed for 2 hours or less. The other one is their PERPETUEM. It is designed with protein at a 3 to 1 ratio. There are several benefits to this in the way that you can consume it. You can mix it in a water bottle with as many servings as you need depending on the length of your ride or you can make a paste for a gel flask in a cocentrated form and then keep straight water in your bottles. This also has a excellent electrolyte supplement in it. Check the other drinks around and see where there carbs come from. Most are straight from sugar and not from long chain complex carbs. Sugars give you a quick buzz but they loose the gitty up and go as fast as they come. The web site has more info on this that you can read for hours.