USFS National Forest System Trails · San Juan National Forest · Colorado · Updated June 2026
Aspen Loop (USFS trail 631) is a 33.8 mi trail in San Juan National Forest, Colorado. Mountain-bike use here is accepted but discouraged in USFS data, with Class 1 e-bikes also designated.
Can I bike Aspen Loop?
| Use | Status | Season on record |
|---|---|---|
| Mountain bike | Accepted but discouraged | — |
| Class 1 e-bike (pedal-assist, 20 mph) | Allowed | Jun–Nov |
| Class 2 e-bike (throttle, 20 mph) | Allowed | Jun–Nov |
| Class 3 e-bike (pedal-assist, 28 mph) | Allowed | Jun–Nov |
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
Aspen Loop (USFS trail 631) is a 33.8 mi trail in San Juan National Forest, Colorado. The figures here are pulled from the official US Forest Service trail data for San Juan National Forest, covering the trail's mileage, tread, grade band, and the bike and e-bike uses the agency lists as designated. USFS records list its surface 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. Note that mountain-bike use here is discouraged in USFS records — confirm with the ranger district before riding. The record additionally permits Class 1, Class 2, Class 3 e-bike use, Jun–Nov; recall that Class 1 is pedal-assist, while Class 2 adds a throttle and Class 3 a higher cutoff 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 Aspen Loop?
- Mountain-bike use on Aspen Loop 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 Aspen Loop?
- Class 1, Class 2, Class 3 e-bikes are designated on Aspen Loop in the USFS data.
- How long is Aspen Loop?
- Aspen Loop measures about 33.8 mi in total, summed across its mapped National Forest System segments.
- What is the surface of Aspen Loop?
- USFS data records the tread surface of Aspen Loop as native material.
- How difficult is Aspen 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 San Juan National Forest (USFS trail geometry isn't mapped).
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