I believe the introduction of the flip-flop hub into the tour was about 1911/1912? . There are different strategies, but what I have found is that on the flats, they would ride fixed. Prior to a climb, they flip the wheel to the freewheel side. Lower gearing ratio but more importantly, it allowed coasting for descents. Fixed up a hill isn’t so bad. Spinning out on the downhill side sucks.
Also, walking was quite common back in the day. The domestique was also known to literally push their captain up the climb.
