Buenos Aires (Rancho de la Osa Start)

5 Star (Premiere) Route / ~ Tucson, Arizona / Published: Dec 2022 / Updated: Oct 2026 / Directions

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Notice: The late-summer monsoons of 2026 have made this winter’s riding more rugged. Many routes now ride a full category harder. Get the latest conditions and tire advice →

By riding this route, you will have an impact on wildlife. Please limit group size to 4.

Riding gravel road leading away from Rancho de la Osa.

Leading out! / December 2022

One of the old adobe homes in Sasabe.

Wide open flats of Buenos Aires National Wildlife Refuge.

The wide flats, ~ mile 5.

Bicyclists on dirt road in Altar Valley.

Cyclist riding towards Pajarita Mountains.

~ mile 9.

Expect some wash riding.

Rolling hills in Buenos Aires National Wildlife Refuge.

Riding though small canyon with oak tree.

Baboquivari, ~ mile 27.

The Visitor Center, go!!

Prickly Pear cactus with gravel cyclist.

Drop some coin at the Sasabe Store.

Back to the ranch.

Pink headquarters building at Ranch de la Osa.

Route:

Lollipop | 44 mi

Gain:

2,500 ft

Surface:

~ 100% gravel

Technical Difficulty:

Demanding

Navigation:

Attention Required

Locale:

Remote

Tire Suggestion:

45 mm+

Options:

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This route is a version of the classic Buenos Aires route but starts from Rancho de la Osa, a working dude ranch near the US-Mexico border just outside of the town of Sasabe. The ranch offers lodging and activities like horseback riding and target shooting; it has a full meal service and a great outdoor pool.

From the ranch, there are two Dirty Freehub rides you can do directly; this one and the Sasabe route. For the complete details of this route, please review the original route guide; this guide is an abbreviated version of the original with the start from the ranch.

Map

Brown = gravel / dirt road

Blue = single track

Red = paved road

Purple = paved bike path

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Ride Details

When We Like to Ride This

A really special time to ride Buenos Aires is just after the summer monsoons end when everything is super green. But … you need to find a day that is not too hot, as the route is very exposed route to the sun and wind. Overall, the route rides well fall through spring.

The Start

Lat / Long: 31.49524, -111.56340

Rancho de la Osa. Note – do not use this as a start unless you are staying at the ranch or have made previous arrangements.

Food & Water

~ mile 32 / Visitor Center

Notes & Options

Comments

Have you ridden this route? Got a question? Join the discussion!

Love Where You Ride! Learn More

Buenos Aires - sign Remote, rugged natural beauty. Emptiness. Big views. That’s the Buenos Aires National Wildlife Refuge which has 200+ miles of dirt roads, which just screams, “awesome gravel route.” Mule deer and pronghorn roam the flat plains and rolling hills. Coyotes, foxes, bobcats, javelina, four types of skunks and two kinds of jackrabbits, and a diverse array of reptiles, including rattlesnakes, desert tortoises and occasional Gila monsters, can be found on the Refuge.

Be Informed!

Wildlife Impact

Learn about the impact we have as gravel cyclists on wildlife. And yes, we have an impact, more than we think or see.

Riding in the Desert Southwest

Gravel riding in the desert southwest is unlike anywhere else in the US! It is rugged and demanding with ever changing conditions. You should expect sandy washes, sometimes for miles; you should expect washed-out trail from the heavy summer monsoon rains, and you should expect rocky and gnarly. One year, the riding is great; the next, it is not.

Cows!

This route crosses through open grazing lands where you may encounter cows and cattle. Learn how to handle this situation the right way. Whooping and hollering are not it!!

Ranch de la Osa

A great way to get a deeper experience of the desert southwest is to stay at Rancho de la Osa for a few days and make it your base camp for riding. They have great accommodations, a swimming pool, and numerous activities like horseback riding.

Ridden and Reviewed by:

LindaE (aka 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.

KevinE / 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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