This specification covers performance requirements for helmets used by downhill mountain bicycle riders. Studies have shown higher risk to the head and face for this sport as compared to recreational street riding; hence, this specification requires greater impact protection and provides performance criteria for chin bars on full-face helmets, but does not require full-face helmets. Retention system tests shall be performed before impact testing. The helmet can be impacted anywhere on or above the test line with the curbstone anvil in any horizontal orientation. The ambient test helmet shall be subjected to the chin bar impact test.

1.1 This specification covers performance requirements for helmets used by down hill mountain bicycle riders. Studies have shown higher risk to the head and face for this sport as compared to recreational street riding; hence, this specification requires greater impact protection and provides performance criteria for chin bars on full face helmets, but does not require full face helmets. This specification recognizes the desirability of light weight construction and ventilation; however, it is a performance specification and is not intended to restrict design.

1.2 All testing and requirements of this specification shall be in accordance with Test Methods F1466, except where noted herein.