USFS National Forest System Trails · Custer Gallatin National Forest · Montana · Updated June 2026
Fly Creek (USFS trail 4450) 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 Fly Creek?
| 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, Fly Creek (USFS trail 4450) covers 2.4 mi of National Forest System trail. 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. 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. Bike use is designated as allowed year-round. 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. 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 Fly Creek?
- Yes. Mountain bikes are designated as allowed on Fly Creek in Custer Gallatin National Forest, year-round, per USFS data.
- Are e-bikes allowed on Fly Creek?
- Class 1, Class 2, Class 3 e-bikes are designated on Fly Creek in the USFS data.
- How long is Fly Creek?
- Fly Creek measures about 2.4 mi in total, summed across its mapped National Forest System segments.
- What is the surface of Fly Creek?
- USFS data records the tread surface of Fly Creek as native material.
- How difficult is Fly Creek?
- 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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