официальные источники
вот к примеру выдержка из правил ПАРКА
Sequoia
BICYCLES — Ride only on roads (not trails), single file with traffic, and wear light colors after dark. People under 18 must wear a helmet.
а вот из Yosemite
здесь и
здесь
Biking - Over 12 miles of paved bike paths are available in Yosemite Valley. In addition, bicyclists can ride on regular roads (if they obey traffic laws). Off-trail riding, mountain biking, and use of motorized bicycles or scooters on bike paths are not permitted in Yosemite National Park.
... not allowed to travel off-trail, on unpaved trails, or in wilderness areas. Mountain biking opportunities are available in designated areas outside of Yosemite.
может я зануда и педант, но Tahoe не парк а
лес ( смешно да? ) тем не менее другой статус - другие правила.
и вообще в разных парках правила могут сильно различаться.