Rode 54 miles on Sunday. Started at 7:15am when it was around 80F and finished about 11:30 when it was nearly 100F. I stayed back with my wife for most of the ride and kept cool and relaxed. I did cut loose for a couple of 5-7 mile stretches and ramped it up to 18-20 mph. It felt great to ride that fast, and I stayed within my aerobic zone, but the heat my body generated was cooking me from the inside out no matter how much I drank. It was amazing how fast I started to overheat even though I was keeping my heart rate under control.