I gave up the office about 2PM after skipping lunch (good breakfast though) It was 94 with a heat index above 100 when I left out on a 28 mile ride. Plenty of sunscreen, Shimano sandals, and a loose fitting jersey. I ate a powerbar and drank 16 ozs of water before leaving. I took a 48 oz Camelback that was half filled / frozen in the freezer, then filled it completely with water before leaving. I drank the last of it while pulling up to the house, and it was still cold. I took three large bottles on the bike (its a touring bike), two with water and one with grape Gatorade. I took two GU's. I drank the bottle of Gatorade on the ride, pacing myself on sports drink consumption along the way. I drank all the water in the Camelback, and used the other two bottles to keep jersey and shorts wet. It works for me.

I also kept my heartbeat below a predetermined level of what I would call sem-comfortable.

At 15 miles I had to take a whiz, so I knew I wasn't dehydrated. At 24 miles I stopped in a sprinkler system at a school and got doused for ten minutes, bike and all.

The last ten miles were into a 20 mph headwind, so that helped, but they were also slow. It was 98 when I got back home.

The above is a good summary of my midday summer ride routine in Texas. Don't bonk. Take plenty of water. Get well hydrated before you leave. Its worth it. If you quit sweating...watch out.