In reply to Wee Davie:
It's a mistake to look at a highly refined design and assume that there isn't any innovation. Modern bikes, like internal combustion engines, may look similar to original designs but are a world away in terms of sophistication and performance.
In fact derailleurs are incredibly efficient and the latest designs give fast, slick changes. Hub gears, especially large capacity ones, cannot get closer to the efficiency of derailleurs.
Now rim brakes maybe haven't advanced so much but on a road bike they are still the best solution in most cases. The grip levels/mass just cannot justify discs. Of course that's different on a fat tyred mountain bike.
Now on to innovation in bikes in general
- have you looked at a modern ALU frame? Just look at the sophisticated tube profiles and hydro forming
- suspension design
- carbon components
- maxles, hollow BB, tubeless tyres, 10 speed blocks, combined brake/gear levers, dropper posts, disc brakes, etc, etc
- let's not even get into suspension wheels and folding wheels, or electric gear change and adaptive damping, or matrix alloys, clipless pedals,carbon chain rings,etc