I just did a solo century yesterday to get used to some more warm temps over PNW - yesterday was on high 70 and cloud with some sunny spots.
Since I was riding on mostly cloud and colder temps, my body is not used to but taking a lower pace at the start helps for me to keep going later.
Other main issue I see for longer rides is the butt pain, so standing, cream and giving a break is essential.
Hydration is the other factor - if you are not peeing, you should drink more liquid.
I'll be trying the double century in a week, and feels good so far
