For each hour of cycling, aim to drink one large water bottle of about 750 mL. For hard rides of more than about two hours, you will burn out or "bonk" when your body runs out of glycogen (what carbs are turned into) unless you consume at least 250 calories per hour. Factor these two tidbits, and what you expect to eat, into your choice of drink.
Sugars can be useful to quickly recover from low blood sugar and bonks, but carbohydrates are much preferable. The key is diversity: don't try to get all of your calories from the sugars and carbohydrates found in soft drinks. You need a balanced intake of fats, protein, and carbohydrates.
- 750 mL lightly sweetened lemonade: 240 calories
- 750 mL ginger ale: 240 calories
- 750 mL (24 oz) sweetened carbonated drink: 330 calories
- 750 mL 50% water, 50% soft drink: 115 calories
- 750 mL fruit juice: 267 calories
- 750 mL 50% water, 50% fruit juice: 133 calories
- 750 mL tomato juice: 67 calories
- 750 mL beer: 310 calories
- 750 mL whole milk: 400 calories
- 750 mL skim milk: 237 calories
- 100 mL eggnog: 268 calories
Needless to say, soft drinks and anything carbonated in general will cause significant stomach complaints unless you get out about a half-dozen quality burps before you start riding again. In general, never drink pop on the road, just like you should never have meat when riding.
Instant tea and unsweetened or artificially sweetened "diet" soft drinks contain virtually no calories, so you're better off with water. The carbonation can cause stomach upset unless drunk slowly and regularly, especially when mixed with hot weather and hard exercise.
Similarly, mineral water is generally a waste of money. Unless you know the water to be unsafe (which is not the case in common European destinations such as France), stick with tap water, as it is uncarbonated and more readily available, meaning you have to carry less at any one time.
The amount of minerals dissolved in Perrier and other mineral waters are essentially trivial. For potassium look no farther than peanut butter, and salt or fig newtons are a good source of sodium. Replacing these electrolyte components as they are lost from sweat is essential.
See also information on the fat-burning effects of caffeine. While coffee is also nearly calorie-free and acts as a diuretic (increasing your water requirements), some suggest that the caffeine aids in processing fat thereby extending your energy supply, and provides an mild but instant energy boost.