USFS National Forest System Trails · Grand Mesa, Uncompahgre and Gunnison National Forests · Colorado · Updated June 2026
Fossil Bypass (USFS trail 9478.1A) is a 1.1 mi trail in Grand Mesa, Uncompahgre and Gunnison National Forests, Colorado. Mountain bikes are designated as allowed year-round, with Class 1 e-bikes also designated.
Can I bike Fossil Bypass?
| Use | Status | Season on record |
|---|---|---|
| Mountain bike | Allowed | year-round |
| Class 1 e-bike (pedal-assist, 20 mph) | Allowed | year-round |
| Class 2 e-bike (throttle, 20 mph) | Allowed | year-round |
| Class 3 e-bike (pedal-assist, 28 mph) | Allowed | year-round |
Zooming out: across Grand Mesa, Uncompahgre and Gunnison National Forests, 96% of rideable trail miles are open to mountain bikes — a Bike Access Grade of A.
Watch Grand Mesa, Uncompahgre and Gunnison National Forests for access changes
Email me when USFS mountain-bike or e-bike designations change for trails in Grand Mesa, Uncompahgre and Gunnison National Forests. Free, unsubscribe anytime.
About this trail
Fossil Bypass (USFS trail 9478.1A) runs 1.1 mi through Grand Mesa, Uncompahgre and Gunnison National Forests in Colorado. This profile summarizes what the official US Forest Service trail record says about riding it: how long the trail is, what it's built on, how steep the route grades out, and which forms of bike use the agency has designated. USFS records list its surface as native material. Based on slope, this is a Advanced trail (grade band 12-20%); that reflects steep gradient and is not the same as a technical MTB difficulty rating. Mountain bikes are allowed, open year-round in the data. On the electric side, Class 1, Class 2, Class 3 e-bikes are also designated — Class 1 being pedal-assist only, Classes 2 and 3 adding a throttle and higher assisted speed. The route is mapped as USFS Trail Class 2 on the agency's 1-to-5 development scale, where 1 is the most primitive, minimally maintained tread and 5 is the most developed. Because conditions, closures, and local orders change between data refreshes, confirm the current status with the managing ranger district before you ride.
Frequently asked questions
- Can you mountain bike on Fossil Bypass?
- Yes. Mountain bikes are designated as allowed on Fossil Bypass in Grand Mesa, Uncompahgre and Gunnison National Forests, year-round, per USFS data.
- Are e-bikes allowed on Fossil Bypass?
- Class 1, Class 2, Class 3 e-bikes are designated on Fossil Bypass in the USFS data.
- How long is Fossil Bypass?
- Fossil Bypass measures about 1.1 mi in total, summed across its mapped National Forest System segments.
- What is the surface of Fossil Bypass?
- USFS data records the tread surface of Fossil Bypass as native material.
- How difficult is Fossil Bypass?
- Its grade-based difficulty is Advanced (grade band 12-20%), derived from USFS slope data. This reflects steepness, not technical mountain-bike difficulty.
How we read this data
Grade-based difficulty above is the USFS grade (route steepness), not a technical mountain-bike rating — a gentle-grade trail can still be rocky or technical, and vice versa. Bike and e-bike status come verbatim from the USFS managed-use fields for this trail; we never infer access we can't cite. See our methodology for how the dataset is built and what each field means.
Where it is
Approximate location of Grand Mesa, Uncompahgre and Gunnison National Forests (USFS trail geometry isn't mapped).
Where to stay near Grand Mesa, Uncompahgre and Gunnison National Forests
Find hotels, cabins, and vacation rentals near Grand Mesa, Uncompahgre and Gunnison National Forests — plan your ride.
Top-rated places to stay near Grand Mesa, Uncompahgre and Gunnison National Forests
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Riding Grand Mesa, Uncompahgre and Gunnison National Forests?
Trail-access updates and trip ideas by email.