The last four days the east coast was hit by a heat wave. We didn't realize the actual temp the first day traveling 56 miles followed by days of 74, 63 and 53. A Canadian said it was 44 C. Lots of water and whatever aid to stay hydrated. Started mixing 3 teaspoons of sugar and a 1/4 teaspoon of salt in 28 oz. bottles. Rosie describes the taste as dishwater like. Only a woman could appreciate the taste of such given their normal domestic obligations. ;) I'll continue to work on my formula.
We switched from our normal bike jerseys to a long sleeve wicking shirt, mine purchased at Walmart and Rosie's at LL Beam. Try it, you'll feel much cooler. BTW, my Walmart brand was less expensive and works just as well, just in case we have shirt snobs out there.
Time in the shade is important. We find a break every ten miles works.
Rosie made an observation the other day. She said it's better that we ride when it's cooler because tensions rise with the temperature. Yes, she gets mean. On several occasions I had to forfeit a bottle of water to check her heated attitude.