What I know is that for me, as I'm susceptable to heat exhaustion, I need some sort of electrolyte solution. My stomach doesn't like gatorade very much. And I'd rather not do the mail order thing (that's just me), or run to a store out of my way for just one thing. So I look for solutions in my grocery store.

I live in hot muggy country, where sweat just stays on your skin if you're sitting still. I always pack a bottle of water and a bottle of sports drink for any ride more than a couple of miles. Pretty much, if it involves my road bike, 2 water bottles are required. If it's my town cruiser, I'm cruising the neighborhood, staying very local and may or may not take a water bottle - but I'm also near civilization, and moving much slower!

I do not like getting heat exhaustion, so do what I can to avoid it.