An early drivetrain concept for the safety bike was the shaft drive. Not a weird idea, really, but just not practical for bikes. Most used bevel gears at the end of the drive shaft. One novel technology was the Victor Spinroller. Instead of bevel gear teeth sliding past each other, the friction was reduced by using rollers for gear teeth. Not sure how practical this was, considering the many small rotating parts. It couldn't have been too bad, because CeramicSpeed adapted the idea for use in a multi-speed shaft drive bike a year or two ago.
https://www.ceramicspeed.com/en/cycl...nounces-driven




Steve in Peoria