A year or two ago Greg Lemond said on TV that the introduction of lower gears has made it possible to include more of the crazy steep stages we see nowadays which would have been impossible in earlier years. (Possibly during the Dauphine, speaking of the col de something or other that also cropped up in that years Tour de France) Edit: Mont du Chat 2017 I think Edit edit. Although the 1974 TdF went over that, so it clearly wasn't impossible. Maybe my memory is at fault. As usual.