Today’s invention is a way to provide relatively simple gearing for a bicycle.
Both front and rear sprocket wheels have arms which are extensible, being driven outwards (or inwards) by eg pressurised hydraulic fluid. Continuous gear changing could be achieved by electrical switching of two hub-mounted pumps.
At the ends of the arms, roller bearings engage with the chain (more arms might be required than shown, for the smoothest possible operation).
A light, springloaded idler wheel is used to keep the chain in tension and avoid slippage.
It might also be possible to have a system tuned so that the arm lengths are individually optimised in realtime for a given rider, on a given gradient and as a function of pedal position.