Oh, and as for finding the strength the next day: I think the trick also was that we don't go terribly fast. We don't really tire ourselves out much, that way!

And we try to pick routes that are reasonably flat. Serious hills truly kill one's endurance. We're comfortable doing 3,000 feet of elevation in a day's ride, but only if it's gradual. I've done rides that were only 25 miles long and only had about 1,000 feet of elevation, but those moments of elevation were very sharp, steep hills. I felt more burned out after 25 miles of that than after a 130-mile day I once did with about 3,200 feet of elevation ... because most of that elevation was pretty gradual ...