I am a mechanical engineer, and I'm 50/50 on it. The rear hub contraptions aren't too different from the freewheel that's already in a regular bike hub, it just

I am a mechanical engineer, and I'm 50/50 on it. The rear hub contraptions aren't too different from the freewheel that's already in a regular bike hub, it just has an extra spring to wind it back up. The super funky gearbox contraption though? That's a different story altogether. You have a continuously varying normal force on the lever arm throughout the rotation, and I have no idea how long it would last compared to a traditional derailleur setup. Here's the patent, for those interested: https://patents.google.com/patent/WO2010084363A1/en https://patents.google.com/patent/WO2010084363A1/en