The Borealis Yampa
Beyond An Off-Season Hobby
It used to be that when the snow fell, bikes were simply hung up in the garage to collect dust until spring. That is until the fat bike came to be. Suddenly, winter wasn’t
the off-season anymore but fat-bike season. The new breed
of fat bikes has seen some of the most rapid growth in the
sport over the past few years, and riders are not only riding
them, but they’re racing them too. Borealis knows that there
is a contingent of riders out there who are looking for performance out of the fat bike, because those are the riders the
Borealis team is made up of.
WHO IS IT MADE FOR?
The Yampa is designed for riders who want to take their
fat-bike experience to the next level. Whether you spend
half of your year buried in snow and never stop racing year
round, or simply dig the ride characteristics of a fat bike over
other mountain bikes, the Yampa is helping to usher in a
new breed of high-performance, fat-tired machines.
WHAT IS IT MADE FROM?
The carbon fiber frame features 190-millimeter, rear-wheel
spacing; a 100-millimeter bottom-bracket shell; a tapered
head tube; and internal cable routing. The frame includes
mounting tabs for rear cargo racks, as well as three bot-tle-cage mounts—two on the inside of the front triangle and
one underneath the downtube.
WHICH COMPONENTS STAND OUT?
The XX1 is Borealis’ top-of-the-line offering and, as the
name would suggest, features a SRAM XX1, 1x11 drivetrain
with Race Face’s Turbine crankset and Narrow Wide single
chainring. Along with the carbon frame, the cockpit is primarily carbon fiber, with a Truvativ handlebar, seatpost and
Despite the frame’s racy appearance, it is designed to fit some
of the widest tires available and comes spec’ed with Surly’s 4.8-
inch Lou knobbies mounted on Surley Clown Shoe wheels.
HOW DOES IT PERFORM?
Moving out: The Yampa’s position strikes a balance
between a race-ready cross-country feel and all-day comfort.
Without any suspension to dial in, the big question
is what tire pressure is correct for the given
Finding the right pressure takes a bit
of experience. Running too little or too
much pressure exaggerates the same
issues you’d experience on a stan-
dard mountain bike. Too much air
and pedaling along seated will have
you bouncing out of the saddle; too
little air will simply make pedaling
tougher and increase your chances
Pedaling: For riders who spend
much of their time on fat bikes, the
Yampa will seem as though it is acceler-
ating forward in leaps and bounds. With
most of the fat bikes weighing much more
or featuring more flexible steel frames, the
stiffness and lightness of the Borealis make it feel
like a true high-performance bike by comparison.
Borealis notes that the frame, including the shaped tubing of
the rear triangle, has been designed to increase rider comfort.
While this may be true, it is hard to discern apart from the feel
of the large-volume tires.
Climbing: In most situations where you’ll ride the Yampa,
the ground will likely be covered in snow or sand. This type
of terrain requires keeping enough weight on the rear tire
to maintain traction. Thankfully, the riding position put us
enough over the massive rear tire to make traction almost an
afterthought. When we did need to get out of the saddle on
steep pitches, we found the ergonomic Ergon grips to be a real
Cornering: The Yampa doesn’t exactly look like a nimble
steed, but you’d probably be surprised by how well this big guy
can tiptoe around things, especially at slow speed. The stability
of the extra-wide tires means that navigating tight situations at
nearly a standstill is possible.
Once the speed picks up, the big tires grip loose corners as
if they were on solid ground. The flip side is that on harder
surfaces, the Yampa can feel less connected to the trail because
there is less for the meaty tires to dig into.
Descending: With some of the fat bikes we’ve ridden, the
frame and fork can feel a bit overwhelmed by the inertia of the
big wheels at speed. This is not the case with the Yampa. The
stiff frame and fork help the bike feel more like a cohesive unit
than a mountain bike with a pair of tractor wheels.
Descending through rough terrain will remind you that
while the tires are large and forgiving, they still aren’t a
replacement for the benefits of modern suspension. While the
tires compress and absorb some of the trail’s energy, much of
the energy is transferred right back to the rider, with only the
rubber of the tires and tube acting as a damper. The Yampa