Originally Posted by jock

FWIW, my thoughts on sport drinks

The keys to hydration are getting an appropriate amount of fluid into the body prior to the event, and learning how much and when to consume more fluid during and after the event. You do this through training, learning how to adapt to different weather conditions, effort levels, states of health/mind, etc. along the way.

Your primary sources of energy are glycogen stores (found in the blood, muscles and liver) and fat stores. Fat stores are difficult to convert into usable energy, so glycogen gets consumed first. Once you run out of glycogen you bonk. The best way to avoid bonking is to load your glycogen stores properly prior to the event, and tune/optimise your body's consumption of glycogen through training that is appropriate for the event that you will be competing in.

Water is useful for hydration. It is also good for helping food down on a big ride, washing lenses on rainy days, cleaning wounds, washing hands, finding punctures, getting even with the plick in front of you in the peleton, getting dust out of the eye, fending off fido, and hydration.

Sport drink is useful for hydration because it contains water. The small amounts of raw carbs and salts may have some fluid uptake benefit for some of the population. The quantities of carbs involved are too small to delay the onset of glycogen depletion, so sport drinks are not an energy source. There is a place for sport drink on the bike alongside the water bidon. There is no real place for sport drink off the bike (unless you're a triathlete, but there's no real place in sport for triathletes! Keep training).

Energy rich foods, sports bars, and gels won't stop you from bonking, they only delay the inevitable. However, they could make the difference between winning a 3 hour event and coming home with your tail between your legs. The best timing and quantities for consumption are learnt during training.

You don't get any benefit from exertion without recovery. SO eat well, keep the fluids up, and get to bed on time. Trust me, you won't miss the Simpsons after the second night.