When it came time to design the Yampa, the team at Borealis drew from years of experience at the bleeding edge of fat bike development and a desire to build the best possible tool for the job. You see, these guys have been riding fat bikes since it involved welding together pairs of standard width rims, so they've seen fat bikes develop from their infancy. Borealis adopted new standards for components and construction in hopes that it could deliver a product that improved on the competition in every measurable way, and with builds coming in well under 30 pounds, we'd have to say that they've hit their mark. And it's not just the light weight that makes the Yampa so appealing. With its proven XX1 drivetrain and Surly rims and tires, it's downright bulletproof too. Welcome to the high tech fat bike revolution.
Borealis built the Yampa frame using the most up to date carbon fiber construction methods. Beyond shedding grams, the composite construction has enabled Borealis to finely tune the flex and build a strong frame that will hold up to year 'round use. The profiling of the seatstays in particular enables added vertical compliance, while the oversized chainstays keep the pedaling responsive when you stomp on the gas. Tire clearance was paramount, and accordingly, the Yampa is able to clear massive 4.8 inch tires on a 100mm wide rim. To achieve that degree of clearance without resorting to a weaker offset wheel, the Yampa uses a Borealis 190mm spaced rear hub. The result is a dishless rear wheel, perfect drivetrain alignment with the 100mm threaded bottom bracket shell, and more than enough clearance for the drivetrain regardless of your tire choice. Naturally, there's plenty of extra clearance for mud, snow, or anything else you're likely to find yourself riding through. The head tube is a tapered affair, which yields incredible stiffness when paired with Borealis's thru-axle equipped carbon fiber fork. It's equipped with three bottle cage mounts, to keep you hydrated for long hours in the saddle. And at 1270 grams for a medium frame, this just may be the lightest fat bike frame in existence.
SRAM's XX1 drivetrain got the nod for the Yampa's top-end build. It forgoes the front derailleur in favor of a wide range 11 speed cassette, which offers a nearly identical range to a standard double chainring equipped drivetrain. The crankset is a Raceface Turbine 100mm setup, with a narrow-wide tooth profile that offers all the chain retention you could ask for, even without a guide. SRAM's XX brakes handle stopping duties, and the cockpit is primarily Truvative hardware with a WTB saddle and Ergon grips. The wheels are Borealis's own hubset, featuring a 190mm quick release rear and a 135mm 15 QR thru-axle front hub. They're laced with double butted spokes to Surly Marge Lite rims, wrapped in 3.8 inch Surly Knard tires. It all adds up to a blisteringly fast snow-race bike, that you'll still want to ride long after spring has come around.
The Borealis Yampa XX1 complete bike is available in four sizes, from small to extra-large, and in the colors Black/white, and Black/red.
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I rode the XX1 Yampa last weekend in Moab, and the combination of light weight and unreal traction made for fun times on steep slickrock. Deep sand was no problem either. Those huge tires may be as good in the desert as they are on the snow. A full-suspension trailbike with conventional 27.5 or 29 inch wheels will always be my primary dirt machine. But a quiver is good, and I had always thought a fatbike would make a good third or fourth mountain bike, with a light hardtail and a long-travel playbike ahead of it. After riding the Yampa, I would consider it a strong contender for the 2nd spot. For a lot of riders it could be a good year-round primary bike. I have customers riding fatbikes on Florida beaches, Mississippi river floodplains, Louisiana levees and tidal flats, as well as the expected Northern snowmobile trails. If you can think of somewhere where you ride where regular mountain bike tires tend to spin out or sink in, a fatbike is going to do better. And Borealis has addressed the weight and handling deficiencies of the tanklike steel fatbikes that came before.
had the opportunity to ride this bike at Outerbike in Moab this year and had an absolute blast on it. The bike was so light weight and agile i totally forgot i was riding a rigid fatbike. I was actually hammering alongside guys with regular mtn bikes.The XX1 is a nice addition to this bike. It shaves weight on the bike and you dont throw chains! According to Borealis this bike weighs in at 25 lbs without pedals-crazy for a fatbike. If you are in the market for something to ride over the winter months in the snow or in the sand this is definitely the fatbike to get!
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