Thanks for all the food for thought. Luckily I have plenty of time to digest it.
I realize that the two things I love are cycling and the high from getting into the zone at a hard pace. High speed doesn't do anything for me, though. Maybe that's why I like riding into the wind.
Possibly I could get that same cardio zone from an elliptical or stair master and leave the bike for pleasure.
Anyway, no hurry.