Been thinking about this now... 1970s

Back in the day we had 10 speeds, that is, a five speed freewheel. In the back a common find was about 13-21 or 14-28 Regina. Up front 52/42 on the chain ring. Friction shifters (non-indexed). Also the bikes were of longer wheel base and more flexible.

Climbing was a real chore but at 6 feet tall and 152 pounds and 22 years old I was climbing out of the saddle pretty easy. I remember my upper chest just being even above the bars and my hands on the hoods pulling up as I mashed as well as pulled on my rat traps.

Today's bikes have a different configuration. More gears, shorter wheel base, different angle on the seat tube and position of the bottom bracket. They are not giant differences but certainly must change the mechanism of action to be sure...