Trail News / The Inyo National Forest Announces New Over Snow Fat-Biking Opportunities

The Inyo National Forest Announces New Over Snow Fat-Biking Opportunities

These trail opportunities are pending adequate snow fall. The grooming operation requires at least 18 inches of snow. The following is a policy change announcement. We will be mobilizing grooming operations as soon as there is enough snow.

The Inyo National Forest announces that new over snow fat biking opportunities are available for the 2018 winter season.  The following areas are now open to over snow fat bike use:

Groomed motorized OSV trails identified on the Eastern Sierra Winter Recreation Map as “Snowmobile Routes.” Click here for information.

Obsidian Dome and Shady Rest Park Trails Nordic Recreation Areas identified as “Nordic Routes” on the Eastern Sierra Winter Recreation Map. Click here for information. 

Here is the USFS Interactive Map

The Inyo National Forest over snow vehicle (OSV) trail grooming program has been ongoing within portions of the Mammoth and Mono Lake Ranger Districts since 1993.  The forest grooms approximately 85 miles of OSV trails annually using funding from the California Department of Parks and Recreation.  These groomed trails are open to motorized vehicles specifically designed for over snow use, such as snowmobiles, and to non-motorized uses such as walking, cross-country skiing and snowshoeing.  The 1992 Forest Order prohibiting the use of non-motorized bikes on groomed trails is not reflective of new, appropriate recreation activities and did not contemplate changes in biking technology when originally drafted, therefore the forest is opening up the opportunity for over snow fat bike use on these groomed trails. 

The Inyo National Forest is working collaboratively with the Town of Mammoth Lakes, Mammoth Lakes Recreation, Mammoth Lakes Trails and Public Access (MLTPA), Sierra Eastside Mountain Bike Association (SEMBA), Mammoth Mountain Ski Area, and Mono County to provide consistent information for users on the over snow fat biking opportunities now available, on proper trail etiquette, and on signage and wayfinding. 

Winter sports enthusiasts are encouraged to have a copy of the Eastern Sierra Winter Recreation Map, found at or available at the Mammoth Lakes Welcome Center, so that they can responsibly plan their activities.   

Here are some handy maps with information for Spring 2018:

81/2 X 11

11 X 17

The Mammoth Lakes Basin (including all snow-covered areas above the road closures on Lake Mary Road and Twin Lakes Road) is closed to over snow fat bike use during the period of operation of the Tamarack Cross Country Ski Center. Bikes are prohibited on groomed Nordic trails, on the Public Access Corridor, and everywhere else in the Mammoth Lakes Basin. Bikes will be permitted in the Mammoth Lakes Basin after April 17, 2018, subject to posted rules and regulations. Mammoth Mountain Ski Area will, however, partner with SEMBA, the Inyo National Forest, and other groups to carry out organized fat bike special events. 

To ensure the enjoyment of the trail system for all users, the Inyo National Forest and collaborative partners encourage proper trail etiquette for over snow fat bike users.  Fat bike users should yield to all other users, leave room for others to pass (don’t ride side-by-side blocking the trail), don’t ride in cross country ski tracks or in such a manner as to disturb cross country ski tracks or skating lanes, and don’t ride in soft conditions (if you leave a rut deeper than 2 inches, it’s too soft).  

The Inyo National Forest provides a wide spectrum of winter recreational activities. Visitors and residents can vastly improve these recreational opportunities, reduce conflict, and protect the forest resources by practicing common courtesy and respecting others’ experiences.


• Respect other trail users. Be courteous and yield right of way. All users yield to grooming machines.
• All multi-use trails are two-way traffic.
• Always stay on the right-hand side of the trail. Pass on the left.
• Beware of blind turns! Slow down for oncoming traffic. Speed limit in congested areas is 15 mph.
• Please avoid all roads or areas posted with closures or restrictions, or as shown as closed on map.
• Keep your dog leashed at all times. Pick up and dispose of any dog waste on and off trails.

Winter Recreation Guidelines

• Purpose-built fat bikes only:
3.8” wide tires or wider with a recommended tire pressure = 6-10 PSI

• Fat bikes yield to all other users.

• If you leave a rut deeper than 2 inches or can’t ride in a straight’s too soft to ride!

• FIRM SNOW is the BEST SNOW. Conditions may deteriorate over the course of the day. Beware of icy patches.

• Winter travel in the backcountry requires proper gear and appropriate clothing. Be self-sufficient!

• Use extreme caution when recreating at night. Be visible and use the brightest lights you can find.

• Be friendly! Have fun! Share the trail!

Dan Holler, Town Manager