I too am struggling with the heat and humidity on my rides. Not a morning person, hard to get riding before about 9:00. Today I rode 15 miles at a 16 mph pace, hydrated with water (probably not enough), and after the ride I was whipped. I know I need to set the alarm and start my rides earlier, but I'm prepping for a September 50 mile ride, so the training and the ride itself will take me 3 hours and it'll be low-90s by the time I'm wrapping up. I have to adapt to the heat, and so far it hasn't happened.


One thing I do is use water as my primary hydration, but the night before a ride I freeze a Polar water bottle full of Gatorade. As I ride, the frozen Gatorade begins to melt, so I have ultra-cold Gatorade to drink for the duration of my ride. That helps. I still need to get a handle on why the fatigue and loss of performance is occurring in the last parts of my ride.