USFS National Forest System Trails · Black Hills National Forest · South Dakota · Updated June 2026
Deerfield Lake Loop (USFS trail 40L) is a 11.1 mi trail in Black Hills National Forest, South Dakota. Mountain bikes are designated as allowed year-round, with no Class 1 e-bike designation on record.
Can I bike Deerfield Lake Loop?
| Use | Status | Season on record |
|---|---|---|
| Mountain bike | Allowed | year-round |
| Class 1 e-bike (pedal-assist, 20 mph) | — | |
| Class 2 e-bike (throttle, 20 mph) | — | |
| Class 3 e-bike (pedal-assist, 28 mph) | — |
Zooming out: across Black Hills National Forest, 34% of rideable trail miles are open to mountain bikes — a Bike Access Grade of C.
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About this trail
In Black Hills National Forest, South Dakota, Deerfield Lake Loop (USFS trail 40L) covers 11.1 mi of National Forest System trail. 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. USFS records list its surface as native material. USFS slope data puts it in the Advanced band (grade band 12-20%), meaning a steep climb — keep in mind this measures steepness, not trail technicality. Bike use is designated as allowed year-round. No e-bike class (1, 2 or 3) is designated on this trail in the USFS data, so treat it as a non-motorized route unless a posted order says otherwise. 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. 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 Deerfield Lake Loop?
- Yes. Mountain bikes are designated as allowed on Deerfield Lake Loop in Black Hills National Forest, year-round, per USFS data.
- Are e-bikes allowed on Deerfield Lake Loop?
- No e-bike class (1, 2 or 3) is designated on Deerfield Lake Loop in the USFS data.
- How long is Deerfield Lake Loop?
- Deerfield Lake Loop measures about 11.1 mi in total, summed across its mapped National Forest System segments.
- What is the surface of Deerfield Lake Loop?
- USFS data records the tread surface of Deerfield Lake Loop as native material.
- How difficult is Deerfield Lake Loop?
- 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 Black Hills National Forest (USFS trail geometry isn't mapped).
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