if im on my dh bike i will always wear my full face, neckbrace, and knee pads. if the course is rocky i will wear a chest vest too. have had knee surgery 5 times from a serious accident which i broke both legs and both ankles so i pretty much never risk it not to wear the head gear. really should get some elbow pads too as joints like knees and elbows can stuff u up later in life. im 21 and have a constant limp that will never go away so best be safe than sorry