Most important bicycle improvements of the past twenty years.
So like how important was the jump from 7 speeds up through 12 speeds? When I ride an older 8 speed system I like how it seems to feel a little more solid with the thicker chain. But also the thinner chains of ten speed and up seem to be able to go at more extreme angles.
it seems that triple front derailleurs are gone now.
through axels do feel more solid though I’m not sure how much they really matter unless you’re putting a lot of weight on it.
Cheap carbon seems to have won out in frame design.
disc brakes are better at stopping but with some rubbing issues and slightly more complicated maintenance.
maybe my favorite advancement has been suspension seatposts and improved saddles like vulcanized rubber and new leather designs.