In for Testing: The Diamondback El Oso Dos Fat Bike

The Diamondback El Oso Dos is a fat bike made for trail and snow, and we're getting a feel for this bear of a bike this winter.

If you had to go to Google and find the Spanish to English translator, well then, you’re not alone. So did I. It has been far too many years since my college Spanish classes. If you didn’t, then I will save you the trip. El Oso means ‘the bear,’ which is a fitting name for this brawny 26-inch Diamondback fat bike.

Every winter, my rides become vicarious through different forms of the internet while locals take their fat bikes out and continue to get a regular dose of the outdoors. That’s important if you’re not a regular skier or boarder. I’ve actually had the El Oso here for more than a few weeks, but now winter is back in Colorado, and I’ll be able to get some quality time wrestling with the Bear.

Diamondback has had the El Oso in its lineup for a little while, and the build kits are separated by factors other than just price and component spec, although that is still the majority of the separation between the Uno, Dos, and Tres models. The Uno has a steel frame and fork, and is built to last a lifetime. The tires are more of a “cruiser” tread, with smaller knobs for better rolling efficiency off the trail, and the Uno has a 2×9 drivetrain.

Skipping ahead one, the Tres has an aluminum frame and a Manitou Mastadon 100mm fork, a Shimano 1×11 drivetrain, and a dropper post.

The El Oso Dos, pictured above is the middle child in the brand’s offering for the fat bike. Diamondback sells the Uno for $850, a Dos for $1,500, and a Tres for $2,200 and the bikes can be found online at retailers like REI (on sale now),, and others.

The $1,500 El Oso Dos has an aluminum frame and a rigid fork. Shifting is controlled with a 2×10 Shimano Deore M6000 drivetrain. The front chainrings are 36/24t, and the cassette is an 11-42t. The El Oso also has a rigid seatpost (with a quality quick-release, thank goodness) and Kenda Juggernaut 26×4.5″ tires. The Bear gets some quality TRP Slate X2 hydraulic disc brakes on this build as well.

Like the 2×10 drivetrain, another interesting thing to note on El Oso’s build spec is the 70mm stem and the 740mm wide handlebars, which lend some responsive XC traits to this fattie.

I’ve now ridden the Bear a small handful of times and have a decent feel for the fat bike. Considering the massive tires, it still feels quite responsive and the geometry feels akin to an XC/trail bike hybrid. Keep an eye out for the full review soon.

⭐️ Find the Diamondback El Oso online at retailers like REI (on sale now),, and others.