I was actually going to bump this thread up with a comment ... although I do use the pills I mentioned above on particularly long, hot rides, I use something else in addition to them.
I drink 100% pure orange juice, and eat beef jerky.
100% pure orange juice has a lot of potassium in it (and Vitamin C, etc.) so it provides one of the main electrolytes. It also provides calories and helps to replenish your liquid.
Beef jerky provides sodium ... and also calories and protein - both very important for long distance riding. I'll also use things like potato chips or corn chips for the sodium.
I did a century yesterday in 30°+ temps and blazing sunshine. I forgot to take my electrolyte pills, so I made a point of drinking orange juice at every place I stopped, and eating something salty. I was fine all the way through the ride.