Rear Derailleur
Full ceramic bearings are standard on AITA ceramic jockey wheel/pulley of the rear derailleur. It spins freely in your fingers and doesn't waste energy in the real system. ZrO2 full ceramic races build the strength and Si3N4 grade 3 ceramic balls deliver the results. It only consumes 9.7% of the power compared with Shimano Dura Ace and Ultegra wheels in average, and 25% of SRAM Force/Rival's. No lubrication is required hence it can bring the service as simple as rinsing under the tap water.