Charlie Bell (Cabeza Prieta National Wildlife Refuge)

5 Star Route

Note: This is a 5 Star Route, meaning that it is a highly curated, premier riding route.

Cabeza Prieta, Spanish for “dark (or dirty) head,” refers to a lava-topped, granite peak in a remote mountain range in the western corner of the refuge.[US Fish & Wildlife Service]

This is one of the more unique routes we have published. It includes a 5-mile out-and-back hike at the end of the bikeable section, to an area with petroglyphs dating back to 8000 BC-AD 500. The ride features a dichotomy of the desert: beautiful rolling desert terrain with giant Saguaro cactus and harsh, barren desertscrub where little grows. The hike takes you up and over Charlie Bell Pass and down the Growler Mountains west side to Charlie Bell Well and the petroglyphs.

The route is mostly within the Cabeza Prieta National Wildlife Refuge (NWR). The refuge “was established in 1939 for conservation of the wildlife resources of the Sonoran desert, primarily the desert bighorn sheep. Today, special care is also given to the endangered Sonoran pronghorn, endangered Lesser Long-nosed bat, and other desert wildlife and plants. In 1990 over 90% of the refuge was designated Wilderness, creating one of the largest wilderness areas in the lower 48 states.”[Cabeza Prieta NWR Kiosk]

(Photo Credit: NPS)
(Photo Credit: Critter Science)
(Photo Credit: US Forest Service)

Adventure / Gravel Route

Out & Back: 30 miles / 1000 ft gain (plus 5 miles, 500 feet of optional hiking, highly recommended!)
– Surface: ~ 100% gravel
eBike Friendly: Yes
– Location: ~ 2 hours, 10 minutes west of Tucson, Arizona
– Published: February 2021

Technical Difficulty & Risk[what this means]

Advanced- (Overall)

  • Technical Riding Difficulty: Moderate-
    Most of the riding is on relatively flat terrain. There are several wash crossings and some short sandy sections.
  • Navigation Challenge & Risk: Low
    The route is a straightforward out & back.
  • Remote Risk: Advanced-
    The likelihood of seeing someone else in the Cabeza Prieta NWR is low. The only vehicle we saw on a January weekend was a US Fish & Wildlife service vehicle.

When we like to ride this ..

Fall through early spring. We love this route from late February to April, when the flowers are in bloom. Ideally, we like to do this route in the early morning when the sun begins to rise. The lighting is magical, and the opportunity to see wildlife is greatly enhanced.

Note, some years have a season fawning closure for Sonoran Pronghorn (antelope). This is usually from early spring (mid-March) through early summer (mid-June); please see the Cabeza Prieta NWR website for more details.

The Start

Cabeza Prieta National Wildlife Refuge Headquarters. Parking, water, and flush toilets.
Lat / Long: 32.386088, -112.872833

Go Local!

After your ride, drop some coin at one of the restaurants in the Ajo Town Plaza, or better, come to Ajo and make a long weekend of it. Arts, culture, and riding! What could be better? You can find more information on where to eat, where to stay, and what to do at Ajo – Local First Foundation, Visit Arizona, and the Ajo Chamber of Commerce. Also, a great Instagram feed to follow is VisitAjo.

For help with Ride, GPS files, etc see the “Help with …” page. To learn how to download the routes for free, see “Using Our Routes …” page.


Red = paved road
Brown = gravel / dirt road
Purple = sidewalk
Green = hiking track

Ride Details

Seeing a Sonoran pronghorn in the wild is a rare and thrilling experience. The Sonoran pronghorn is smaller and lighter colored than its North American relatives. An adult Sonoran pronghorn stands about 3 1/2 feet high at the shoulders, weighs 90 – 125 pounds, can run at speeds of 60 miles per hour, and has a 270-degree field of vision for up to four miles. When startled, they often show their white tail and rump patch before fleeing. Sonoran pronghorn are superbly adapted to their desert environment, being able to tolerate high temperatures and go without water for extended periods of time.

The Sonoran pronghorn was federally enlisted as an endangered species in 1967. Following a severe drought, only 21 Sonoran pronghorn remained alive in the United States in 2002. In cooperation with the Arizona Game and Fish Department and many other partners in the U.S. and Mexico, the U.S. Fish and Wildlife Service started a captive breeding program to increase Sonoran pronghorn numbers and ensure their survival. [Kiosk at Cabeza Prieta]

(Photo Credit: US Fish and Wildlife Service)
Miles 0 to 4.5 / Rasmussen Road / Hard-packed Gravel (mostly)

From the Cabeza Prieta Headquarters, take the sidewalk north a short distance until intersecting a paved road. This is Rasmussen Road; go left. Initially, the road is paved but quickly transitions to a double-wide gravel road. The surface is hard pack, embedded with rock to make for a cobblestone-like texture. And there is some washboard.(Play micro-video) After being jostled around for 5 minutes or so, we stopped and reduced pressure in our tires. We went low, below 16 psi in a 2.1″ 29er wheel configuration.

At ~ mile 2.3, the main road continues straight, but the route goes directly west on a much smaller BLM road. Take it! The scenery is better and the riding more fun; albeit, a bit more rugged.

At mile 3.4, you reconnect with the main road (Rasmussen road), and at mile 4.3, cross a cattle guard and enter the Refuge.

Miles 4.5 to 15 / Charlie Bell Road / Gravel

As you enter the Refuge, the road narrows to a single lane, and the desert squeezes in with beautiful Giant Saguaro cactus, Ocotillo cactus, and Palo Verde trees.(Play micro-video) Over the next several miles, the route splits Childs Mountain to the north and Cardigan Peak to the south. The brilliant white dome atop Childs Mountain is a radar installation.

Childs Mountain was taken over by the military back in the 1950s, and radar systems designed to warn against Soviet attacks were built, but never used. The military maintained a working force of about 100 to 200 men at any one time on Childs Mountain during most of the 1960s, as part of the ongoing military operations in the area. Some radar installations were used for other means, the mountain being part of the Barry Goldwater Air Force Range. By the early 1970s, the military abandoned the whole place, leaving the buildings behind. In 2000, a newer FAA “ARSR-4” (Air Route Surveillance Radar) radar dome was built on the southernmost summit. This dome is controlled remotely so there is no need for there to be anyone up there except for the occasional service worker. [The Mountains of Arizona]

At mile 7.5, North Ajo Peak comes into view at the 11 o’clock position. Here you will also find a windmill at Little Thule Well, a desert water station for those in trouble, and the turn to Copper Canyon. Continue straight.

The remaining portion of the outbound leg of the ride is slightly downhill. The landscape slowly transitions from lush Sonoran desert to dry, barren desertscrub. At mile 11, to the left, is Pack Rat Hill, and atop it a structure. This marks “an ongoing Sonoran Pronghorn wildlife management operation and a one-square-mile semi-captive breeding enclosure to help re-establish the Sonoran Pronghorn population. The 2002 drought wiped out 80% of the Sonoran Pronghorn population leaving only 21 animals within the refuge.”[Hike Arizona]

Beyond this are the Growler Mountains. The low point in the range is Charlie Bell pass, the high point of the hike. The ride continues through the desertscrub, and through Daniels Arroyo.(Play micro-video) Just beyond the wash, find a place here to lock your bikes and put on your hiking boots.

Miles 15 to 17.5 / Charlie Bell Road / Hike

The road continues from here but is almost unrideable. It is strewn with baseball to basketball-sized boulders. It almost looks like the rock was trucked in and dumped. From here to Charlie Bell pass is a bit over a mile with 150 feet in gain.

Continue west from Charlie Bell Pass, descending, following the double track into Growler Valley. In about 0.8 miles, the trail begins to follow a wash with large boulders. Continue westward for another 0.7 miles, and the Charlie Bell windmill and well appears. To the right of the windmill, look for boulders with a black desert varnish; many will have carved petroglyphs, most of the petroglyphs are to the north of the well.

In the Cabeza Prieta National Wildlife Refuge, there are more than 3,400 documented petroglyphs, with 2,700 within 700 feet of the Charlie Bell well; most of them date to the Archaic period circa 8000 BC-AD 500. [Old Pueblo Archeology Center]

(Photo Credit: Old Pueblo Archeology Center)
Miles 17.5 to Finish / The Return / Hike and Gravel Roads

Turn around and repeat! Hike then bike. Note, the return leg is the more difficult adventure, as it is more uphill than downhill; 1000 feet of gain, 400 feet of loss.

Food / Water


Ride Notes

Our choice for tires would be 50+ mm with reduced pressure. There is nothing along the route that would preclude 40 mm tires; however, the ride quality will be harsher.

Bring a lock for the hike portion. A cable lock that can go around a tree will work as you will find a number of trees at the wash, Daniel’s Arroyo. Bring hiking shoes.

To access the Cabeza Prieta NWR you need to obtain a permit.

If you do this route, we could use your help with a few pictures of:

  • the cattle guard entering Cabeza Prieta
  • locking up bikes
  • the hike
  • petroglyphs
  • Charlie Bell Well
  • some of the mural art from the town of Ajo
Ride Options

This route is perfect for an ebike! The hike is 5 miles, which is ~ 2 hours. Exploring for petroglyphs is another 1 to 2 hours. The 30-mile bike out and back is an additional 3 to 4 hours. Thus, by standard bike, the adventure is 6 to 8 hours. An ebike could make the time much more manageable.

People travel from near and far to see some of the refuge’s native species, including the Greater roadrunner, the Sonoran desert toad, the Sonoran desert tortoise, the Gila monster, and chuckwalla lizard. [Cabeza Prieta NWR Kiosk]”

(Photo Credit:
Desert Toad
(Photo Credit:
Pima Co. Library)
Desert Tortoise
(Photo Credit:
Gila Monster
(Photo Credit:
Sonoran Desert Explorers)
Chuckwalla Lizard
(Photo Credit:
California Herps)

Ridden and Reviewed by …

Gravel Girl / Team Dirty Freehub

She loves a good day of gravel like most people like a good book. She’s always amused by the outdoors and the wild adventures. Gravel Girl is a Co-Founder of Dirty Freehub.

Captain O / Team Dirty Freehub

He should have “Never Stop Exploring” tattooed on his chest! He loves adventures on bikes and is a Co-Founder of Dirty Freehub.

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