1. It doesn't take much time riding in the rain to get to the point where you cannot get any wetter, and seeking shelter becomes irrelevant. Then you just go with it.
2. Heavy rain is very loud when it hits a cornfield. I could have sworn a few rows back from the road, out of sight beyond the corn, there was a gravel plant, grinding big rocks into little ones.
3. An office supply store clear sheet protector does a serviceable job keeping a map and cue sheet dry and usable, regardless of rain or sweat.
4. Heavy rain 20 miles from home doesn't necessarily mean you're going to get a single drop of much-needed moisture back at the house.
5. It's entirely possible to overstress the base of a tube's valve stem by cranking down the little retaining nut to get enough stem exposed through an aero rim for a pump to actually work.
6. It's entirely possible for that stressed valve stem to not give up the ghost until you're 35 miles into the next morning's ride.
All of this "learning" aside, I still had a great ride. I took a route almost completely new to me, so I saw unfamiliar sights, found some great little-traveled roads, discovered a new breakfast ride destination a manageable 21 miles from home, and ended up with the longest solo ride I've had in over 25 years. Total was 53, at an average speed of 15.6. I had one stop for a cinnamon roll and iced tea at said breakfast place, while I waited out the last 15 minutes or so of the rain. And I had that previously mentioned unintended "rest" stop at mile 35.