Why would anyone start a bike trip not being in the best condition possible? Riding into shape while on a tour uses the same priciples as training before the ride; exertion followed by recovery. You either do it before the ride or during the ride. My preference is training/conditioning before the ride in controlled situations so I can handle most situations on the tour and still have some reserve left at the end of a hard day.
My wife and I started a long tour in good condition, and averaged over 50 miles a day for 74 consecutive days. I was 64 years old at the time. We've also started long tours with less conditioning, and it made a significant difference. At my age it takes longer to recover from hard days, and if I don't follow up with a short day or a rest day, I just keep going deeper in the hole. Being in good cycling shape before the tour starts increases endurance and facilitates quicker recovery; and you dont have to take as many rest days while on the tour.
Last edited by Doug64; 11-07-19 at 02:27 PM.