USFS National Forest System Trails · Custer Gallatin National Forest · Montana · Updated June 2026
Brewster Divide (USFS trail 4419) is a 5.4 mi trail in Custer Gallatin National Forest, Montana. Mountain bikes are designated as allowed year-round, with Class 1 e-bikes also designated.
Can I bike Brewster Divide?
| 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 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
Brewster Divide (USFS trail 4419) runs 5.4 mi through Custer Gallatin National Forest in Montana. 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. Underfoot, the trail is recorded as native material. USFS slope data puts it in the Intermediate band (grade band +8-10%), meaning a moderate climb — keep in mind this measures steepness, not trail technicality. Mountain bikes are allowed, open year-round in the data. The record additionally permits Class 1, Class 2, Class 3 e-bike use; recall that Class 1 is pedal-assist, while Class 2 adds a throttle and Class 3 a higher cutoff 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 Brewster Divide?
- Yes. Mountain bikes are designated as allowed on Brewster Divide in Custer Gallatin National Forest, year-round, per USFS data.
- Are e-bikes allowed on Brewster Divide?
- Class 1, Class 2, Class 3 e-bikes are designated on Brewster Divide in the USFS data.
- How long is Brewster Divide?
- Brewster Divide measures about 5.4 mi in total, summed across its mapped National Forest System segments.
- What is the surface of Brewster Divide?
- USFS data records the tread surface of Brewster Divide as native material.
- How difficult is Brewster Divide?
- Its grade-based difficulty is Intermediate (grade band +8-10%), 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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