USFS National Forest System Trails · Salmon-Challis National Forest · Idaho · Updated June 2026
South Fork Big Creek-Iron Cr. (USFS trail 4078) is a 12.3 mi trail in Salmon-Challis National Forest, Idaho. Mountain-bike use here is accepted but discouraged in USFS data, with Class 1 e-bikes also designated.
Can I bike South Fork Big Creek-Iron Cr.?
| Use | Status | Season on record |
|---|---|---|
| Mountain bike | Accepted but discouraged | — |
| 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 Salmon-Challis National Forest, 26% of rideable trail miles are open to mountain bikes — a Bike Access Grade of C.
Watch Salmon-Challis National Forest for access changes
Email me when USFS mountain-bike or e-bike designations change for trails in Salmon-Challis National Forest. Free, unsubscribe anytime.
About this trail
South Fork Big Creek-Iron Cr. (USFS trail 4078) is a 12.3 mi trail in Salmon-Challis National Forest, Idaho. 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. Underfoot, the trail is recorded 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. For traditional mountain bikes, use is discouraged according to USFS 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 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. 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 South Fork Big Creek-Iron Cr.?
- Mountain-bike use on South Fork Big Creek-Iron Cr. is discouraged in USFS records, though Class 1 e-bike use is designated. Confirm current rules with the managing ranger district.
- Are e-bikes allowed on South Fork Big Creek-Iron Cr.?
- Class 1, Class 2, Class 3 e-bikes are designated on South Fork Big Creek-Iron Cr. in the USFS data.
- How long is South Fork Big Creek-Iron Cr.?
- South Fork Big Creek-Iron Cr. measures about 12.3 mi in total, summed across its mapped National Forest System segments.
- What is the surface of South Fork Big Creek-Iron Cr.?
- USFS data records the tread surface of South Fork Big Creek-Iron Cr. as native material.
- How difficult is South Fork Big Creek-Iron Cr.?
- 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 Salmon-Challis National Forest (USFS trail geometry isn't mapped).
Where to stay near Salmon-Challis National Forest
Find hotels, cabins, and vacation rentals near Salmon-Challis National Forest — plan your ride.
Top-rated places to stay near Salmon-Challis National Forest
Availability and prices from Stay22 partners (Booking.com, Vrbo, Expedia). We may earn a commission from bookings, at no extra cost to you.
Riding Salmon-Challis National Forest?
Trail-access updates and trip ideas by email.
More trails in Salmon-Challis National Forest
80.4 mi · Advanced grade
31.7 mi · Advanced grade
29.8 mi · Advanced grade
20.9 mi · Advanced grade
20.8 mi · Advanced grade
18.7 mi · Advanced grade