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First Impression

The Borealis Yampa arrived in two large bike boxes, one for the frame and components, and the other dedicated to the massive wheelset. Lifting the carbon frame out of the box, I was astonished at the lightness of the bike. Wheels are the defining feature of a fat bike and, in this case, they were unadulterated bike porn and mammoth. It really is a refreshing experience giving a fat bike a proper inspection for the first time.

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After the initial excitement, a quick ride around the carpark felt reassuringly bike-like, sturdy and relatively nimble. All concerns about giving this bike a tough test on the mountain were dispelled.

The Bike

I was not familiar with the Borealis bike company before stumbling upon the Fatbike Co website. Borealis is based in Colorado, USA (a fact proudly promoted on the chain stay of the bike) and they focus solely on carbon fat bikes. At present, they make two models the Yampa and the Echo. The Yampa (the model reviewed) is a rigid fat bike, while the Echo is a hardtail that features the RockShox Bluto fat bike fork.

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Our test Yampa was the base XOX9 model. The drivetrain is a 2x10 setup with, as the name would suggest, a mixture of SRAM X9 and X0 parts. The brakes are mechanical, Avid BB7. While this may seem outdated for a modern mountain bike, it’s likely a nod to the tundra or desert adventurer requiring simple maintenance and repairs. That being said, the higher specced models come with modern hydraulic mountain bike brakes. These superior models also drop a chainring and use either a XO1 or XX1 drivetrain.

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The wheels, the stars of the show, feature Borealis’ own huge FH1 hubs, Turnagain FR80 rims and Surly Knard 27TPI tyres. The tyres on our test bike were 3.8” wide which some may consider slim for a fat bike. But don’t despair, the frame is designed to handle tyres with a width of up to 4.8”.

Due to the cavernous volume of the tyres, it took far more effort than usual to pump them up, even though the recommended pressure is only between 0.6 and 1.1 bar. I’d hate to get stuck with a flat on the trail with only a hand pump or a couple of bombs.

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I really appreciated the look of the Borealis carbon frame. Other than the wide stay spacing (to fit the giant wheels) and oversized bottom bracket, the Yampa could pass as an ordinary carbon mountain bike. While the stay width wasn't a concern, the huge BB was the the only aspect of the frame that really worried me. The unfamiliar distance between the crank arms led to a considerable amount of pedal striking when starting out on the Yampa.

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The Ride

I had this bike for two weeks, and I made the most of it, riding nothing but the Borealis. The bike was taken on single track missions, dirt road rides, used to commute to the office and the mandatory beach ride. Unfortunately there was no snow on hand, so I can't comment on the bikes capabilities at the upcoming Snow Epic.

As the controls and gearing are regular mountain bike components, operating the Yampa feels much like a normal bike. The rigid fork, even with the fat tyres, takes a bit of time to get to grips with. But as a fat bike first timer, it's easy to just jump onto the Yampa and start having fun.

I learnt that tyre pressure is the most important factor to the ride and feel of a fat bike. I started riding the Yampa with just under a bar of pressure making the fat bike feel ordinary, like a heavy mountain bike.

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Once I dropped the pressures (I neglected to measure how much), the bike started feeling less like a mountain bike and more like the monster truck I had imagined. The massive grip and sensation of the tyre sidewall flex all making the ride feel unique and resulted in a constant grin.

On the trail

I rode the Yampa down single track with the same mentality I ride my mountain bike. It didn’t disappoint.

Surprisingly, the fat tyres forced me to change many of my regular lines on the trail. For example, the wheels no longer squeezed through narrower gaps or instead of going around an obstacle, it now made more sense to smash right over it. It was like rediscovering my local trails and a hugely enjoyable experience.

Ascending smooth single track was a breeze but the more technical climbs, like the rocky Canary trails at Jonkershoek, were tough on the Yampa (and the rider). Lifting and steering the Yampa up rock gardens is tiring and truthfully more hassle than fun. In fact, with the large tyres, it is easier to ignore the designated trail and simply pick a fat bike friendly route up the mountain.

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Going downhill was a different story, as the Yampa felt right at home on the descents. I really enjoyed directing the fat tyres down smooth and rocky trails alike. I even attempted a few of the smaller jumps and drops, which felt odd as the bikes mass was mostly in the wheels but I do believe that with a bit of practice I'd be getting airborne with confidence.

The sensation of speed on the Yampa was somewhat muted. My guess is that the added stability and grip gives the rider an enhanced sense of control that you don’t usually feel on the skinnies. Despite the clear impression that it felt slower, the Yampa was no slouch. I even scored a few Strava PRs.

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The highlight on the trails for me was the bikes cornering. The grip from the tyres is unnatural, giving you the impression that there is no chance of sliding out. Berms felt amazing, giving me the confidence to actually turn in hard enough to go horizontal (at least it felt that way).

As you may expect, the biggest disappointment out on the trails were the Avid BB7 mechanical brakes. While most of my time on the Yampa the brakes were adequate, there were a few occasions where I could have done with a bit more power. Especially considering that the tyres have enough grip on hand to shift a continent. A further complaint is the fatigue caused by the mechanical braking, activating a cable is not as pampering on the hands as hydraulics. By the end of the longer trails, my hands were screaming for the flats.

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Yes, I commuted on the Borealis and it was great fun. In fact, I got so sidetracked by enjoying the ride that my commute took double the usual time. My slower more peaceful route meanders through greenbelts and side roads, here the Yampa excelled at enjoying the scenery. The bike turned out to be a very soothing pre- and post-work companion.

On the black stuff, the Borealis can gain up a fair amount of speed. I even shocked a few roadies, until they realised the drafting potential. It would be a stretch to claim that fat bikes are good on the tar but what they do seem to be well-suited for is riding on the roadside verge (which can often be a more pleasant place than inside the yellow line). The fat tyres of the Yampa did differentiate the tar from the verge and were happy to maintain the same momentum while switching between the two.

The Beach

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As expected, the Yampa felt at home on the beach. It could ride over soft sand that a conventional sized tyre could not. Speeding along the hard sand in the shallow water was surprisingly exhilarating. While I’m not an experienced beach cyclist, I don’t see there being a better suited bicycle style than a fat bike. If you’re wanting to ride on the beach, a fat bike is the tool for the job.


The Yampa had an amazing affect on people. They all had an instant attraction to the bike, and not just cyclists. I had excited statements, questions, and stares from most people that saw the bike. It was astonishing. I've never felt like more of a rockstar.

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I once overheard fat biking evangelist Mannie Heymans explaining that you get more attention riding a fat bike down the main road of Windhoek than in a Ferrari. I can’t speak for the Windhoek locals but I wouldn't be surprised if this were true. So if your rigid single speed or your brightly coloured Santa Cruz with matching Enve rims (I’m just jealous) aren’t getting you as much attention as you would like, look no further than a shiny fat bike.

In the end

I had immense fun riding trails on the Borealis Yampa. Riding a fat bike like a mountain bike goes against convention, and therein lies the appeal. It removes you from everyday riding and forces you to enjoy the fat bike for what it is, riding a (ridiculous) bicycle.

The base model Borealis Yampa is a solid and well-equipped bike, the brakes being the only shortcoming. With the padding of the big tyres the rigid fork wasn't an issue but I'm very intrigued to see what fat biking is like with the Bluto fork.

The Yampa was my go-to bike for the full length on the loan and I was sad to see it go. I don't see a fat bike ever be my primary bike but if I had some spare cash, I wouldn’t be too hard pressed to add a fat bike to my stable. Having the option to instantly change the riding experience of your local trail is well worth it.

Specifications: Borealis Yampa X0X9

  • FrameBorealis Yampa

  • ForkBorealis FF1
  • HeadsetBorealis Sealed Bearing
  • HubsBorealis FH1
  • RimsTurnagain FR80
  • SpokesWheelsmith Black Straight
  • NipplesWheelsmith Silver Brass
  • Rims StripsTurnagain RS80
  • TyresSurly Knard 27TPI
  • TubesTurnagain MagnumFAT
  • HandlebarTruvativ Stylo T30
  • StemTruvativ Stylo T20 100mm
  • SeatpostTruvativ Stylo T20
  • SaddleWTB Pure V Comp
  • GripsLizard Skins 496s
  • CranksetRaceFace Ride 22-36t
  • Front DerailleurSRAM X9
  • FD MountWolftooth FD Mount
  • Rear DerailleurSRAM X0 Type2
  • ChainSRAM 1031
  • CassetteSRAM 1070 11-36
  • ShiftersSRAM X9 Trigger
  • BrakesAvid BB7 w/ 160mm rotors
  • DT/CS ProtectorLizard Skins
  • RRPR46 000