Hammer Nutrition Endurolytes Fizz - 12-Tubes $59.40
If you read the ingredients of most "sports" drinks you'll notice that they're full of refined sugars, and if you're lucky you get some sodium. You need the sodium, because it helps your body actually absorb the water, and you sweat it out during exercise. That said, Hammer Endurolytes Fizz is so much more than just a sodium re-supply. First, it's not sugary, which is important because simple sugars will catapult you into the boom/bust energy cycle that leads to irregular performance. Rather, it's sweetened with natural stevia.
Second, Endurolytes Fizz contains two key ingredients athletes need when they work out for two hours or more -- or whenever they work out and sweat even moderately. Those two ingredients are Potassium and Calcium. Potassium you likely know because most cyclists will carry a banana for a longer ride. While a banana is a great source of carbs, the thing that likely makes you feel re-energized is the potassium, since it helps regulate your heart, so that beats are both consistent and smooth. Remember that the heart is a muscle too. As an athlete you need potassium to keep your heart, and other muscles, working efficiently. For potassium to do its job it has to work with a regular supply of sodium, which is in Endurolytes Fizz.
As for calcium, if you've ever been on a ride and experienced urgency, or muscle spasms (and heaven forbid, both!) it's possibly due to low calcium levels. It's easy to sweat out a great deal of calcium on hot days, which in the long term can lead to bone density loss, but in the short term will sometimes lead to a nervous bowel or muscle spasms, and you don't want either. By the way, Endurolytes Fizz also contains magnesium, which is also needed to prevent muscle spasms (a.k.a., the dreaded calf cramp).
Hammer Endurolytes Fizz is a critical ride supplement to prevent cramping, inefficient muscle contraction, and lower GI issues. It comes in tubes of 13 tablets and is available in three flavors -- Grapefruit, Lemon-lime and Mango. Take one tab, broken in half, dissolved in two water bottles for a 2-3 hour ride. Double that if you sweat more or if it's hot out. Bring an extra tab along in a plastic envelope in your jersey, just in case.