borealis yampa carbondale carbon fatbike091613_1059


When we spoke with Adam about the new Borealis Carbondale tubeless fatbike rims just before the show, he told us they would have an SL Yampa build under 23 lbs. The truth? The bike is actually 21 lbs 9 oz, without going to extremes on the build.

Get the scoop on possibly the lightest fatbike around and check out the Carbondale rims first hand, next.

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Borealis conveniently had a stand equipped with a scale to see the lightness first hand. The early samples of the Carbondale rims weigh 570g just like Adam claimed.

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The tubeless carbon rim is actually pretty interesting with tubeless tape not even needed under the bead of the tire. So far Borealis has been using packing tape but plans to have Stan’s tape made in the best size. Their current set ups run tape only as wide as the spoke holes with the tire bead resting on bare carbon. With one scoop of sealant per wheel the tires have stayed inflated nicely.

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While a selection of lightweight components have been assembled, nothing is particularly crazy. An XX1 drivetrain sits next to XX brakes and Truvativ Noir carbon bars and seat post. A 3t stem, ESI grips, a carbon Selle Italia saddle, and Race Face Next carbon crank are also used. Wheels are Borealis’ Carbondale rims laced to their own hubs. 45NRTH Husker Du tires are set up tubeless with Stan’s sealant. Oh and it’s a large frame.

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All that and it’s still rack compatible. Metal threaded inserts bonded into the stays will accommodate a rack.


  1. Yeah, nothing too extreme there, aside from the top of the line carbon everything and XX1 drivetrain. Just your average, run of the mill $10000 carbon fatbike. Nothing to see here, move along.

  2. Innovative? Taking a bicycle component and making it out of carbon fibre is about the least imaginative, least innovative thing you can do these days. The bike looks awesome, but is derivative in nearly every way.
    I really, really want one, anyway.

  3. There is no way that one scoop of sealant will remain liquid. My experience has been that a week later most of the sealant will be absorbed into the casing. If you want flat protection you are looking at 2-4 scoops.

  4. Absolutely awesome. Between this and the Crumpton / FWB 8.88 lb. (4.03 kg!) road bike, I personally love to see the builders pushing of the envelope, tech-wise. (Obviously, as long as it is safe for the intended use. Duh.)

    As for the complaints about the (admittedly ridiculous) cost, hey: you don’t read Car and Driver to drool over the Subaru Outbacks, Toyota 4Runners, and Ford Explorers (=the cars that most of us drive.) You read the magazine to salivate over the Aston Martin Vantages, the Ferrari Californias, and the McClaren 12c’s.

    Lighten up, hombres…

  5. agreed, Eric. how do you forget that you’re in vegas? sit back & enjoy the lap dance, gentlemen. what happens in vegas…you know the rest..

  6. Can you run fatbike rims tubeless down to 7-8psi without burping? My fat bike is mostly for snow riding and tempted, but not going to deal with pumping up a fat with a small pump because of a burp.


  7. Don, I run mine tubeless in the winter at 5 to 5.5 psi. No issues at all. 2 scoops of Stan’s per tire. And the Stan’s lasts all winter due to the colder temps vs in summer where it can dry up after a few months of riding.

  8. don – that is basically the pressure that everyone runs their tires at in the winter tubeless… or in the sand. I ran mine with tubes down to 5psi in the winter… I have my tubeless setup now at 7.5 psi and am riding on dirt. Bud/Lou.

  9. This looks like it would be fun to ride. As much fun as a Surly Pugsley or a Salsa Hogwarts,
    or even a Specialized guadela-who-the-hell-cares.

    If you live in a place that demands a fat bike, you’re not going to care if it’s three lbs lighter.

    The Tubeless feature is of interest, but show me a bead-lock of some kind. I have no interest in risking a burp at 8 psi.

  10. thanks nathan/tad, my mukluk is going on a huge diet this season, it’s around 36 pounds and thinking with carver obeast fork, wheels/tires I can take a huge chunk off. I’d love a 23 pound fat, but will shoot for sub 30 first. 🙂


  11. Fatbikes have become a victim of type casting (which seems predominant in this industry/market) . Take your heads, unwrap them from fatbike being for snow, sand, and mud and realize that the sky is about to break loose with more dry trail oriented fat bikes (full suspension included) because once you try them in the dry dirt, you get it. They are just fun as hell to ride on your normal trail rides, and they will slay a bikepark with FS. and yes you can run above 10 lbs enjoyable, they are not sloggy or slow when you put a reasonable amount of air in them. higher pressure fat tires combinesd with air suspension wil make for superb fun.

  12. I rode it in Vegas and I can tell you that this thing rips. It handles and feels like a mtn bike. Maybe better. I was blowing by people on the demo trails and even passing them in the rough off-track crap.

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