Borealis Yampa Carbon Fatbike: Short term review

So, a couple weeks ago i got my hands on a new winter toy: A carbon fiber fatbike! I've been anticipating the delivery of the new steed since earlier this summer when i first learned of the Borealis Yampa frames, and that Freewheeler Bike Shop would be carrying them (i think Curt ordered a dozen or more right off the bat). The frame showed up a while before iceman, and the components were slowly trickling in and teasing me with visions of ripping down the lakeshore and carving snowed in singletrack. After the excitement and post-iceman depression i was in desperate need of a cycling pick-me-up. In the nick of time, Curt got the components in stock and Logger did a fine job of assembling this glorious mode of transport.

As you can tell, i no sooner that got it outside of the shop than started photographing the glory!

Of course, the first thing i did when i got it home was to fine tune the fit to a more aggressive stance and prep it for it's inaugural voyage. It looks a little more like this now:

Stem slammed, seat jacked... that's more like it

Once i had the bike fitted to my specifications i burst out the door in full cold weather regalia and set about seeing just what this machine could handle! First i noted how responsive it was for such a large wheeled beast. Although the acceleration is slower due to the greater rotational weight, i didn't notice it feeling too sluggish. I would compare it to a turbo-diesel automobile; takes a minute to spool up that turbo, but once you hit the right RPM it's all systems go! I headed directly to the nearest park with anything resembling singletrack and set about tackling the steepest hills i could find. I had the bike built with SRAM 1x11 with a 34T ring upfront. For reference, i'm used to my Niner which is geared 1x10 (11-32 cassette and 38T ring upfront). This fatbike with the new drivetrain climbs hills like a tank, you just drop it into a creeper gear and scale grades up and above 30 percent. The drivetrain was expertly tuned by Freewheeler's very own Logger so naturally it snapped into gear immediately and produced literally no noise. I'm very happy with the 1x11 setup and am seriously thinking about making the leap on my Niner now...

That cassette is a marvel of engineering!

Solid Raceface Turbine cranks to put down some meager power at best...

Look at that bottom bracket girth!

When i left my house, i had measured the tires at around 18 psi, which i realize is firm for a fatbike. I could tell right away on the trails that i was giving up ride comfort and traction as a result. Curt was forward thinking when he built this rig, and set me up with the matching Borealis hubs laced expertly by the Wheel Department over at Velocity to their awesome new Dually rims. He also selected some fine rubber in the form of 45NRTHs Dillinger 4" model, and set them up tubeless. I have to say, comparing the tubeless Dually's to some of the wider tire/rim combos with tubes that the difference is staggering. I soon stopped and aired those bad boys down to 10 psi and instantly noticed a smoother ride. The traction also went up ten-fold as it made little effort to overtake roots and stones that would normally jar my teeth half loose. I tackled another hill at a nearby park which although only 25 feet in height, packs a near 35% grade of loose grass and leaves. I'm pleased to report that with the largest cog on the cassette i was able to climb without blowing out a hammy!

These tires also happen to accept metal studs for when winter really picks up. I haven't had any issue with burping the tires from the Dually rims. The whole package is stout!

The rigid fork and thru axle are robust pieces. Borealis did a nice job with the fitment of the hub/axle/fork.

The rear hub has a great sound and feel to it. It engages quickly and after over 100 miles of punishment i haven't noticed a change.

So, what conditions have i put the fatbike through exactly? Well i'm glad you asked... Here's a rundown of the flogging:

1. First trip out was brief, i hit Manhattan park to check the confidence on leaf covered, steep trails. I rode through the sand pit several times, and hit some greasy trails to check mud-shedding. Tooled on over to Fuller park and tested out some really steep stuff and more tight trails.
2. Second trip was a pro-longed urban MTB course. Threw in some mulch, railroad tracks, railroad bridge, long and steep descents and stair descents. Long story short, the bike is confident riding off and down stuff.
3. Threw in a few more urban MTB rides with a lot of mud, sand and tall grass. Rode through a dried up swamp which was interesting. It's amazing how much grass you can wrap into the drivetrain and still be able to ride...
4. Three loops at Luton. One loop with fast segments and waiting at the end of each mini-loop. One loop of recovery and one full loop without stops. This bike can really soak up the roots and rocks that otherwise pose a threat on normal MTB tires. Also, i was able to hammer corners without worry in the leaves. This thing has a ton of traction and good handling.
5. Went out this past Sunday in the epic rainstorm. The bike does awesome with foot deep or less puddles and creeks...

I've got 110 miles in so far, and a pretty good cross-section of terrain to report on. The rest of the build is pretty standard:

Brakes: SRAM XO hydraulic w/Ashima Ai2 ultralight 160mm rotors

Cockpit: Carbon Niner flat bar, carbon Niner seat-post, alloy Niner stem

Seat: Fizik Ardena

Pedals: Shimano SPD

Grips: Lizard Skins rubber w/custom Freewheeler Lock-on clamps!

Robust!

 I like the feel of these grips, and the latest version of SRAM XO hydraulic brakes.

I chose a smattering of tried and true durable goods. The pedals are M525 which weight half a metric ton, but are indestructible. The cockpit is not boutique by any means, but built to handle thrashing down Belknap hill at 40+ MPH. The seat is built for comfort and also is near one metric ton. Even with a non-uberlight build this bike tips the scale at 24lbs in full riding decor (pedals, two bottle cages, and tail-light). If one were so inclined to drop an extra couple hundred bucks you could easily slide into the 21-22 pound range.

I plan to partake in several fatbike races throughout the winter months as well as continue training sessions once or twice a week on this beast. Overall, i'm very pleased with this build. The bike can tackle the worst of it with ease, but still carve up some singletrack and post top 10s on serious segments. It's light enough that it feels nimble when pushed to the limit, but not so light that i'm afraid to bomb drop-offs and curbs. I'd like to give a big shoutout to Freewheeler Bike Shop for the sweet build and great timing! I'll report back after I've got to logs some serious training/racing miles on it with an update on how it's holding up!