This is a new bike drive train that does not rely on gears and chains, instead it uses a funny cam mechanism to move a system of pulleys and steel cables. I more or less understand the cam system, but I can’t figure out exactly how the wheel movement works. As for shifting, it is done by changing the position of the pulleys, which means an almost instant shift with no slippage, sort of a constantly variable transmission (CVT). What is left to see is if the cables are less prone to fall off the pulley system than a conventional chain falling off a normal bike.
Update: A commenter showed me prior art and a patent on a design that is basically identical in principle. I tried looking in the Stringbike website and I can’t find any claim as to the source for the design, but from what I see in the original inventors’ website they are actively licensing the patent.