The Jamis Dakar gear hanger is a small, metal piece that is attached to the rear of the Darkar frame. It provides a mounting point for the rear derailleur, which is responsible for shifting gears. If the gear hanger is damaged, it can cause the derailleur to malfunction or even fall off the bike. In some cases, a damaged gear hanger can even make the bike unsafe to ride, ensure you keep yours up to date!