USFS National Forest System Trails · San Juan National Forest · Colorado · Updated June 2026
Lower Rim (USFS trail 309) is a 2.4 mi trail in San Juan National Forest, Colorado. Mountain bikes are designated as allowed, May–Nov, with no Class 1 e-bike designation on record.
Can I bike Lower Rim?
| Use | Status | Season on record |
|---|---|---|
| Mountain bike | Allowed | May–Nov |
| 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 San Juan National Forest, 29% of rideable trail miles are open to mountain bikes — a Bike Access Grade of C.
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About this trail
Lower Rim (USFS trail 309) is a 2.4 mi trail in San Juan National Forest, Colorado. 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. The tread is mapped as native material. Based on slope, this is a Easy trail (grade band +5-8%); that reflects gentle gradient and is not the same as a technical MTB difficulty rating. Bike use is designated as allowed, typically May–Nov. 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. 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 Lower Rim?
- Yes. Mountain bikes are designated as allowed on Lower Rim in San Juan National Forest, typically May–Nov, per USFS data.
- Are e-bikes allowed on Lower Rim?
- No e-bike class (1, 2 or 3) is designated on Lower Rim in the USFS data.
- How long is Lower Rim?
- Lower Rim measures about 2.4 mi in total, summed across its mapped National Forest System segments.
- What is the surface of Lower Rim?
- USFS data records the tread surface of Lower Rim as native material.
- How difficult is Lower Rim?
- Its grade-based difficulty is Easy (grade band +5-8%), 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 San Juan National Forest (USFS trail geometry isn't mapped).
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