In the late 1800s, bicycles were the major inspiration for all the most mechanically creative minds that had been yearning for an outlet, almost everything was new, nothing was an established standard, and creativity wasn't stifled by the concerns of a mature technology in a modern developed economy. My favorite cars to see at shows are Edwardian and Brass Era because of all the surprising ideas that were tried that we tend to think of as modern and, since the mechanicals are so easy to see, I find it fun to discover these things.
Every 10-20 years (long enough for people to forget the previous attempt) certain concepts are dusted off as amazing new improvements for bicycles. I suspect a number of them are from people that are looking for expired patents they can reintroduce as new concepts to scam money from investors or in crowd funding.