With heat index over 105 I just rode my normal 30 mile route to town from 1100 to 1510 with a 40 min lunch break. I pedaled the portion I normally pedal unpowered, about 2/3 of it on the flatter portions. I drank 20 oz water in route and 40 oz of cold diet soda 2.5 miles from the end. You have to get used to the heat; I don't air condition my summer camp at all. I do have trees and a fan. After 45 minutes in the hot sun spraying weeds, I spend 10 minutes in the shade in front of the fan. Usually 7 gallons of weed killer a day. Oh, btw, I'm using the type of weed killer that a jury in California says causes cancer. I have been using that for 25 years. You have to take all these warnings about the terrors of life with a grain of salt. Preferably lite salt, to replace the potassium I sweat off. I cover all my skin with dark cloth to prevent sunburn, and wear a hardhat to protect my forehead ears & neck, and allow the wind to blow underneath the suspension. The bike helmet is ventilated nicely, no sweat in the eyes today.