Since this is IMHO, the idea that you need to be hammering tons and tons of water or other fluids so that you’re peeing every hour is a load of crap, but very popular in the lay fitness press.
As a former Cat. 2 racer, it just takes some time to figure out how much fluid you really need during a given ride, but if you are accustomed to being able to drink when your thirsty and can recognize when you actually are thirsty, just drink when you’re thirsty. On a cool day (60 degrees Fahrenheit), I’ll go through a single 20-ounce bottle in a 60 mile ride. On a hot day, I’ve gone through 20 bottles on the same length of ride.
Furthermore, overwhelmingly, the real health risk in endurance events related to water/electrolyte balance is water intoxication rather than true dehydration. Basically, this is due to too much water consumption relative to sodium intake.
As for food, many of the “performance” foods like gels and Clif bars (or Power bars, or Honey Stinger bars, etc.) are *convenient *and fine, but not necessary. Some professional cyclists live on Clif bars, some eat “real” food. The contents of musette (lunch-packs in the Tour de France) range from all energy-food that comes in foil to tuna-sandwiches on rye bread. What’s your personal preference? I started out with all of the “performance” foods but realized that I prefer and seemed to better GI-wise and otherwise with “real” foods. Unlike running, on a bicycle your insides aren’t constantly getting jostled so most people can tolerate solid or even fatty food, so a cheeseburger isn’t a bad way to go if that’s what you’re hungry for and feel like eating. It’s hard to predict caloric consumption without a power-meter although there are websites that will give you a rough estimate, but it you’re going for a really long ride the important thing is just to eat, eat, eat.
There’s a decent amount of new research indicating that you should mix carbohydrate and protein (about 15-25% of calories) energy sources rather than relying solely on carbohydrate energy sources. If you want to drink it, there are a few drinks including Accelerade that has both protein or carbohydrate, but so does a pastrami sandwich on rye.
Food should be joy, riding your bike should be a joy, now go enjoy both at the same time was my rule.