USFS National Forest System Trails · Custer Gallatin National Forest · Montana · Updated June 2026
Derby Gulch (USFS trail 373) is a 2.4 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 Derby Gulch?
| Use | Status | Season on record |
|---|---|---|
| Mountain bike | Allowed | year-round |
| Class 1 e-bike (pedal-assist, 20 mph) | Allowed | Jan–Mar, May–Dec |
| Class 2 e-bike (throttle, 20 mph) | Allowed | Jan–Mar, May–Dec |
| Class 3 e-bike (pedal-assist, 28 mph) | Allowed | Jan–Mar, May–Dec |
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
Derby Gulch (USFS trail 373) runs 2.4 mi through Custer Gallatin National Forest in Montana. 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. Underfoot, the trail is recorded as native material. No grade band is recorded, so a steepness-based difficulty isn't available for this trail. 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 (Jan–Mar, May–Dec) — 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 4 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 Derby Gulch?
- Yes. Mountain bikes are designated as allowed on Derby Gulch in Custer Gallatin National Forest, year-round, per USFS data.
- Are e-bikes allowed on Derby Gulch?
- Class 1, Class 2, Class 3 e-bikes are designated on Derby Gulch in the USFS data.
- How long is Derby Gulch?
- Derby Gulch measures about 2.4 mi in total, summed across its mapped National Forest System segments.
- What is the surface of Derby Gulch?
- USFS data records the tread surface of Derby Gulch as native material.
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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