36 C.F.R. § 7.11
(a) Bicycling.
(1) The following trails are designated as routes for bicycle use:
(2) The Superintendent may open or close designated routes, or portions thereof, or impose conditions or restrictions for bicycle use after taking into consideration public health and safety, natural and cultural resource protection, and other management activities and objectives.
[68 FR 50077, Aug. 20, 2003, as amended at 77 FR 60053, Oct. 2, 2012]