USFS National Forest System Trails · Custer Gallatin National Forest · Montana · Updated June 2026
Blacktail Lake (USFS trail 105) is a 2.3 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 Blacktail Lake?
| 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
Blacktail Lake (USFS trail 105) is a 2.3 mi trail in Custer Gallatin National Forest, Montana. 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. Underfoot, the trail is recorded 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. The agency lists no Class 1, 2 or 3 e-bike designation here; absent a local order to the contrary, that means e-bikes are not an allowed use on this trail. 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 Blacktail Lake?
- Yes. Mountain bikes are designated as allowed on Blacktail Lake in Custer Gallatin National Forest, year-round, per USFS data.
- Are e-bikes allowed on Blacktail Lake?
- No e-bike class (1, 2 or 3) is designated on Blacktail Lake in the USFS data.
- How long is Blacktail Lake?
- Blacktail Lake measures about 2.3 mi in total, summed across its mapped National Forest System segments.
- What is the surface of Blacktail Lake?
- USFS data records the tread surface of Blacktail Lake as native material.
- How difficult is Blacktail Lake?
- 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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