Obviously, what one eats and drinks has a big effect on how you handle the heat. It would be ideal if, like the Tour de France, there were a car with ice-cold bottles following behind and a domestique to bring them to you. Rank does have its privileges!
For those of us who aren't so lucky, there are a few things you can do to get a cool drink when you need it. Try these seven tips to keep you and your fluids cool on a hot ride.
More: Cycling Hydration Myths
Before the ride, fill your bottles with a combination of water and ice. Wide-mouth bottles make it easier to get the cubes into the bottle. I would not recommend freezing your water bottles. Water expands as it freezes so unless you leave the bottles only about 3/4 full you might end up ruining a nice water bottle.
Make an Insulated Bottle
There are a number of insulated water bottles on the market. Some work. Others, not so much. If you have a brand that works for you, great. For others it is a question of trial and error. The technology is there for bottle manufacturers to put a foam liner between the inner and outer skin. That would be a huge improvement over the current offerings that feature air space or reflective foil.
One old-school trick is to cover your bottle with an old, preferably clean, sock. By keeping the sock wet, the evaporative cooling on the outside of the bottle does not necessarily chill the contents, but it does keep them from heating up.
Use the Cage on the Seat Tube
This might be a bit of an urban myth, but in hot conditions, I have found that the bottle on the seat tube stays a bit cooler that the bottle on the down tube. My guess is that the bottle on the down tube shields the warm air from the bottle on the seat tube. Hey, if it works, it works.