Several times, actually.
Once, I started off on a 200k, and was just getting overheated and felt so bad, I called in. I was riding into a headwind and hot and had a flat and missed the first control at 60 miles or so.
Then the next 200k, it was also hot, but I was dealing with it better, until I got leg cramps so bad I couldn't ride, at about the 86 mile mark.
Then once, I started off on a New Year's Day ride. I was going to ride to the ride, but got about 20 miles from the house, was cold and getting colder, sun wasn't up yet, and it was pretty miserable, so I called in.
All three of those were on my Worksman cruiser.
Since then, I've gotten better, have a better bike, better tires, and have learned how to deal with heat a bit better.
__________________
"be careful this rando stuff is addictive and dan's the 'pusher'."