The mountain bike remains - for the time being - out of the picture, Shimao has devised the new technology for urban and trekking bikes, as well as for gravel bikes: The CUES FH-U6060 rear hub not only keeps the rear wheel turning, but is also home to a dynamo. This provides the power for the Di2 system. The Q'Auto components work together to enable automatic shifting. 

In addition to the energy supplier in the center of the wheel, the system is based on sensors in the rear hub for speed, cadence and incline. This means that Q'Auto users do not have to worry about shifting gears - the system selects the gears itself. So-called adaptive learning is designed to adapt to the riding style, recognize the rider's preferences and shift the gears accordingly. 

bike.shimano.com