UDH HangerUDH Explained Engineered to replace thousands of proprietary hanger designs with a single, universal solution, the Universal Derailleur Hanger (UDH) delivers simplicity without compromise. Precision machined from high strength aluminum, this hanger is built for durability while incorporating a smart rotational design that allows it to move backward under impacthelping prevent chain jams and protecting your drivetrain from damage. Standard Mount UDH