Originally Posted by
UniChris
This is definitely a valid concern. However, I know I wasn't eating enough to do the ride on an other than fat-burning basis, which given what I have available to burn might work for a survival trek but not for the ready energy demands of cycling even at my slow pace. And the reason I wasn't eating was that under the conditions the food I'd packed made me feel sick.
In terms of heat exhaustion, for the troublesome hours I was mostly threading through tree-screened corridors within a hundred yards of quite built-up areas so wasn't really concerned; would have been a while before I could get collected by family, but plenty of opportunities to seek or get help. And at refills I probably dumped out almost as much water to replace it with fresh as I had consumed, so was never really low on that despite drinking about as much as I felt I could. Nor was there any shortage of other people riding, and it being a weekday many were a decade or two older than I, though in most cases not going as far. I think I might have at times been in danger of abandoning the ride, but never really in danger danger - avoiding the parts when I might have been getting close to that was why there were a few cases where I walked into the shade rather than riding there.
I had heat exhaustion once in my teens, and the lead up to it sounds almost exactly like what you are describing. The problem is that you can feel like you're keeping just ahead of it, and then it's like a switch gets flipped, and even getting yourself to the shade becomes too difficult. Fortunately, the one time I had it, I wasn't alone, and the friend I was with was able to talk me through getting out of the heat. I don't know whether I would have been able to if I had been alone. The loss of ability to think clearly is really hard to describe, but it isn't anything I want to experience again.
I do a lot of hot weather riding, and I've never had a recurrence, but I gear down on long rides and take frequent air conditioning breaks with lots of fluids.