Great fitness is optional; Reasonable fitness is essential.

I originally planned to ride an epic bike tour. I set out to ride the whole route, no exceptions, including the distance between stages when the rider's were transferred. Toward that goal, I arranged a rigorous training regimen, which I continually modified until there was nothing left but a handful of weekend rides. Arriving in France, I struggled the first couple of days (especially getting used to the loaded bike). My first ride over a climb (Cormet de Roseland) was far harder than I expected and took me about four or five hours, including about a dozen stops. That night I slept for 15 hours and woke up feeling like I had gone ten rounds with Mohammed Ali. However, by the third and forth days, riding up harder climbs was 10 times easier. By the end of the trip, I had little trouble riding 120 miles, over fourteen hours, with about 15,000 feet of climbing. My conclusion is that there is no real need to show up for the tour super-fit because the fitness will come by touring. However, landing in front of the Alpes without pedaling at all for the season could make for an unpleasant experience.