Bunsen Peak Loop - 10mi Strenuous Bike Trail

A person bikes on a trail through a field of sagebrush with mountains in the distance.

This is a ten-mile mountain bike loop through grizzly country with 1,120 feet of elevation gain—strenuous and technical. The first three miles are deceptive: flat dirt road that lulls you into false confidence. Then the northeast face turns vicious, dropping 960 feet in 2.5 miles with sharp curves and cliff-edge exposure demanding full control. Expert riders only, summer and fall. Bring bear spray and arrive before dawn.

Quick facts

Distance Miles: 10
Route Type: Loop
Difficulty Level: Strenuous
Elevation Gain Feet: 1120

Trail profile

Distance Miles: 10
Route Type: Loop
Difficulty Level: Strenuous
Elevation Gain Feet: 1120
Estimated Time: 4–6 hours, depending on fitness and rest at viewpoints
Trail Surface: Mostly dirt road and gravel, with chunky, technical sections on the descent
Trail Features: Bunsen Peak views
Glen Creek drainage
Joffe Lake area
Steep drop-offs with sharp curves
Dirt road/gravel sections
Grizzly bear habitat
Technical descent sections
Trail Highlights: The payoff is the northeast descent: screaming down 960 feet of technical dirt with perfect control through cliff-edge curves. Views of the thermal landscape and Bunsen Peak reward you at multiple points. The final 1,000-foot climb back to the main road is the real battle—grinding fitness and mental grit.

Trailhead & access

Trailhead Location: Bunsen Peak Trailhead, north of Mammoth Hot Springs
Parking Lot Size: Limited—approximately 15–20 spaces
Parking Fill Time: By 7am during peak summer months
Shuttle Required: 0
Shuttle Details: No shuttle service available

Permits & conditions

Permit Details: No permit required; park entrance fee applies
Fees: $35 per private vehicle (7-day pass) or $20 per person on foot/bike
Trail Status: Open (weather dependent)
Seasonal Closures: Winter; park roads typically open mid-April through early November

Facilities & rules

Restrooms At Trailhead: 0
Water Sources: None on trail. Carry all water from the trailhead.
Accessibility: First 3 miles: mostly flat dirt road, potentially rideable by hand-cycle with mountain bike tires. Remaining 7 miles: very steep, technical, with sharp drop-offs and abrupt curves—NOT suitable for casual riders, novices, or those with vertigo. Service dogs permitted but face increased wildlife risk in backcountry.

Safety & strategy

Hazards: Grizzly bears
Black bears
Bison
Elk
Steep drop-offs with sharp curves
High-exposure technical sections
Sustained elevation gain
Hazard Details: Grizzly and black bears are active—bear spray mandatory, and you must know how to deploy it. Stay 100 yards from bears/wolves and 25 yards from bison and elk. Sharp, abrupt drop-offs are common, especially on the northeast descent; cliff-edge curves demand technical control. The 960-foot drop in 2.5 miles and 1,120-foot overall gain test fitness and nerve.
Cell Service: Unreliable; no service guarantee in backcountry
Crowd Level: Moderate to busy during peak summer, limited by scarce parking
Peak Crowd Times: 7am–10am during June through August; weekends year-round (within season)
Best Season: Summer and Fall
Best Time To Visit: Late June through September. Depart by 5:30am—parking fills by 7am. Morning start ensures you finish before dark. Avoid weekends if possible.
Tips Advice: Tighten your boots before the technical sections—ankles take abuse on the drop-offs.
Bear spray on your hip belt, not your pack. Know how to use it.
Carry 3 liters of water minimum—the expose on the return climb is relentless.
Start by 5:30am. Parking is non-existent by mid-morning.
Mountain bikes mandatory; road bikes will wash out and kill you.
Stay 100 yards from bears/wolves, 25 yards from bison and elk.
The descent is technical and fast—full control required on every curve.

More details

Park Area: Mammoth Hot Springs Area, near North Entrance
Trail Markers: Well-worn dirt road, easy to follow the main loop. Some sections less distinct—map recommended.
Dogs Allowed: No, not permitted
Biking Allowed: Yes—required. Mountain bikes essential; road bikes not suitable.
Shade Level: Mostly exposed, especially on the descent and return climb
Emergency Contacts: Mammoth District Ranger Station (nearest emergency contact). Call 911 if within cell range; otherwise, return to trailhead immediately.
Map Recommended: 1
Snow Dates: Late October through April (weather dependent)
Fall Colors Peak: Late September through early October
Insider Tips: The false summit at mile 4 feels like the end—it's not. Push through to the final descent.
The Osprey Falls alternative (6.5 miles round trip from Bunsen Peak trailhead) is much gentler for warm-ups or bailouts.
Descending after 10am risks finishing in fading light—not ideal.
Glen Creek drainage is the steepest, most technical section. Use full braking control, lean back, and respect the exposure.
Family Friendly Notes: NOT family-friendly. The steep descents (950 feet in 2.5 miles) and cliff-edge drop-offs make this unsuitable for children and inexperienced riders. Drop-offs are severe and exposure is real.
Nearby Facilities: Mammoth Hot Springs offers lodging, dining, and ranger services. Nearest campground: Mammoth Campground.
Review Summary: Riders call this a lung-buster with real exposure. The first half on flat dirt is manageable; the second half (960-foot descent plus 1,000-foot climb) separates the fit from the struggling. Most agree: expert technical skill and fitness required. Do not attempt if you're new to mountain biking.

Frequently asked questions

Are there really bears?

Yes—grizzly and black bears are active in this area. Bear spray is mandatory; carry it on your hip belt and know how to deploy it. Stay 100 yards away if you see one.

Can I ride this on a road bike?

No. The dirt road is chunky, the descent is technical with sharp drop-offs, and road bike tires will lose traction. Mountain bikes are essential.

Is the parking really that tight?

Yes—the lot fills by 7am most summer days. Arrive by 5:30am or risk wasting your drive. There are no overflow lots or shuttle alternatives.

How much water do I need?

3 liters minimum. The trail is exposed with zero water sources. Dehydration kills your ride and your judgment around wildlife.

What if I can't finish the full loop?

The Osprey Falls alternative (6.5 miles round trip) is much gentler. Or do an out-and-back from Bunsen Peak trailhead for as long as you want.

Do I need a permit?

No permit required, but the park entrance fee applies ($35 per vehicle, 7-day pass, or $20 per person on foot/bike).

What if I'm alone—is that safe?

Solo travel is possible, but tell someone your plan and expected return time. Carry bear spray, a map, and full water. Know your fitness limits and that emergency response is slow in the backcountry.