The thing is that this gadget has been doing the rounds of trade shows for more than a year with this unfinished detail of having it actually change gear. Ther

The thing is that this gadget has been doing the rounds of trade shows for more than a year with this unfinished detail of having it actually change gear. There is this difference between theory and practice. So even if there was a solution - yours is elegant b.t.w. - then it would take a whole lot of testing and fine tuning to get right. I am actually quite astonished at how bicycle parts evolve, the derailleur took the best part of a century to get indexed gears and those took decades to go from clunky to smooth. What took so long to get right? Scores of refinements were needed, e.g. to the sprocket teeth profiles, to being able to manufacture a decent chain to basics of friction in cables. Then there is the challenge of mass manufacturing these things so they are durable and precise. I am not dismissing the ceramic speed shaft innovation - it gets people thinking - but I doubt my bike will be losing its chain any time soon!