USFS National Forest System Trails · Custer Gallatin National Forest · Montana · Updated June 2026
Chestnut Mountain (USFS trail 458) is a 7.3 mi trail in Custer Gallatin National Forest, Montana. Mountain bikes are designated as allowed year-round, with no Class 1 e-bike designation on record.
Can I bike Chestnut Mountain?
| Use | Status | Season on record |
|---|---|---|
| Mountain bike | Allowed | year-round |
| Class 1 e-bike (pedal-assist, 20 mph) | Restricted | — |
| Class 2 e-bike (throttle, 20 mph) | Restricted | — |
| Class 3 e-bike (pedal-assist, 28 mph) | Restricted | — |
Zooming out: across Custer Gallatin National Forest, 98% of rideable trail miles are open to mountain bikes — a Bike Access Grade of A.
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About this trail
In Custer Gallatin National Forest, Montana, Chestnut Mountain (USFS trail 458) covers 7.3 mi of National Forest System trail. Everything below comes straight from the US Forest Service National Forest System Trails dataset — length, surface, slope-derived difficulty, and the specific bike and e-bike designations on record — so you can check legality before you load up. 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. No e-bike class (1, 2 or 3) is designated on this trail in the USFS data, so treat it as a non-motorized route unless a posted order says otherwise. The route is mapped as USFS Trail Class 3 on the agency's 1-to-5 development scale, where 1 is the most primitive, minimally maintained tread and 5 is the most developed. Treat this as a planning reference rather than a live conditions report, and verify any time-sensitive closure or order with the ranger district that manages Custer Gallatin National Forest.
Frequently asked questions
- Can you mountain bike on Chestnut Mountain?
- Yes. Mountain bikes are designated as allowed on Chestnut Mountain in Custer Gallatin National Forest, year-round, per USFS data.
- Are e-bikes allowed on Chestnut Mountain?
- No e-bike class (1, 2 or 3) is designated on Chestnut Mountain in the USFS data.
- How long is Chestnut Mountain?
- Chestnut Mountain measures about 7.3 mi in total, summed across its mapped National Forest System segments.
- What is the surface of Chestnut Mountain?
- USFS data records the tread surface of Chestnut Mountain as native material.
- How difficult is Chestnut Mountain?
- 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 Custer Gallatin National Forest (USFS trail geometry isn't mapped).
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