USFS National Forest System Trails · Custer Gallatin National Forest · Montana · Updated June 2026
Boundary Reservoir (USFS trail 4032) is a 2.6 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 Boundary Reservoir?
| 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
In Custer Gallatin National Forest, Montana, Boundary Reservoir (USFS trail 4032) covers 2.6 mi of National Forest System trail. The figures here are pulled from the official US Forest Service trail data for Custer Gallatin National Forest, covering the trail's mileage, tread, grade band, and the bike and e-bike uses the agency lists as designated. The tread is mapped as native material. Based on slope, this is a Easy trail (grade band +0-5%); that reflects gentle 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. For day-of certainty on closures or seasonal orders, check directly with the ranger district, since this reflects the USFS data as of the latest refresh.
Frequently asked questions
- Can you mountain bike on Boundary Reservoir?
- Yes. Mountain bikes are designated as allowed on Boundary Reservoir in Custer Gallatin National Forest, year-round, per USFS data.
- Are e-bikes allowed on Boundary Reservoir?
- Class 1, Class 2, Class 3 e-bikes are designated on Boundary Reservoir in the USFS data.
- How long is Boundary Reservoir?
- Boundary Reservoir measures about 2.6 mi in total, summed across its mapped National Forest System segments.
- What is the surface of Boundary Reservoir?
- USFS data records the tread surface of Boundary Reservoir as native material.
- How difficult is Boundary Reservoir?
- Its grade-based difficulty is Easy (grade band +0-5%), 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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