I read that Bafang, the huge e-bike motor manufacturer in China, has come out with a 3 speed automatic shifting bicycle hub for pedal bikes and e-bikes both that can handle 90n-m of torque, comes with different shift points to compensate for different sizes of wheel rims and uses either a chain or gates carbon belt drive. It said that the automatic removes the clutter of a gear shifter on the handlebars and a cable running to the rear hub. This drive train component should work good with a shift kit.