CUES is a recently released line of components designed for city, e-bike, and utility bikes. Not road, not MTB, not light, not earth shattering. Some say that it replaced Tiagra, but it's better than that. The electronic shifting option of the group is unique, through. It is not standard battery-powered Di2, it's called QAuto. QAuto is a system consisting of an electronic shifting rear derailleur and a rear hub that contains a generator and storage bank, which powers the derailleur. I have yet to see one in person.