I really enjoy riding since I joined a club in the early spring this year, I have not had a big issue keeping up with the average rider in the club, however since the humidity and heat soared up since last weekend I am a bit concerned if I should only ride on cooler days. I am worried I will not be able to manage the century ride in August since I may not have enough distance riding under my belt.
Last weekend (90km 56m) it was 34c / 93f and the early part of the ride went smoothly, as it got closer to noon it got very hot and humid. Many big hills still to climb.
I may have overlooked some key items for riding in the heat.
Started with a foot cramp, though it was due to new shoes and clips, then lower back pain started which lead to neck and then a pounding headache. Then my calf’s did not cramp but got very painful. I thought I had not drank enough, but I had downed 1-/12 bottles of water, 1 Hammer formulated and the order was Gatorade. I topped up my hammer drink with fresh water as we passed through a town. I slowed down to a crawl, for the rest of the hills and to conserve what I had left.
I was so glad to make it back to the car, got off my bike I was so dizzy I used the car to work my way around on onto my car seat.

This weekend I froze one bottle of water, half froze one Gatorade, and loaded another bottle with Heed drink with ice cubes and some water. For energy I took a Hammer Gel, Fig bars, and saltine crackers for extra salt because I don’t use salt in my diet, a snickers bar for extra sugar and nuts & salt (does not sit well in stomach).
I did a ride with very few hills but the heat and humidity was still there, the early stretch went well I took drinks about every 15-20min, about 45min into the ride I took in a couple fig bars and crackers about 23mils into the ride we took a good rest in the shade and I took in the snickers bar and finished my Heed drink. I switched to my Gatorade bottle for the ride back and noticed the water bottle was still cool but not frozen.
About 10miles into the return trip it got extremely hot, my head felt like it was cooking whenever I put any extra effort in, I quickly doused my head with some water I had, I felt a lot better after that, I was amaze how much better I felt. Soon after that I me up with the rest of the pack in the shade for a re-group.

What can I do to last longer or improve my ride, I noticed others just keep going and hardly touch their drinks.
I am 50, 5’10 and 160lbs. I have lost 80lbs in the last year and a half, if this makes A DIFFERENCE.