Starting today, Mon November 23rd, White River National Forest guidelines kick in for winter travel. Certain roads are open to motorized winter travel, like snowmobiles.
On plowed roads, cars and other vehicles with wheels are allowed, including mountain bikes. Such modes of travel are not allowed on winter trails, again, including bicycles. Mechanized use is restricted on those trails to create the best wildlife habitat, reduce soil erosion during muddier times, and prevent confrontations between people using trails in different ways.