There have been an unimaginable number of "improvements" to the bicycle over the last hundred years. And all of them have one thing in common: trading off a reduction in efficiency for "insert something else". But that "insert something else" is literally only a problem to people who don't ride bikes, so it ends up being entirely pointless. The modern geared bicycle is up there with things like the paper clip or the can opener as "perfect" designs which can never be fundamentally improved upon again short of advances in basic material science.