I try to drink a lot of water before I start riding. I carry 1 or 2 water bottles, but I don't feel comfortable enough with my riding skills yet to drink and drive...particularly when I am trying to maintain at least an 18 mph pace. Half way through my ride, usually 25-40 miles I will drink a bottle of water. In our heat (just now dropping below 90 degrees), when I weigh myself before and after, I lose 5-7 pounds per ride. I then try to drink about a gallon of water over the course of the evening to rehydrate. Hopefully within the next few months I'll be comfortable drinking while riding.