Carbon Rim Release Photo 2Borealis is one of the newest fatbike companies around, but they’ve already shown they aren’t afraid to push the limits coming right out of the gate with a carbon fatbike, the Yampa. With Yampas only freshly out of the molds, Borealis is already launching their next game changer: tubeless, carbon rims for fat bikes
As far as we know these are certainly among the first tubeless and certainly the first carbon tubeless rims we’ve seen for fatbikes, though we’re guessing they won’t be the last.

Borealis certainly has the jump though, see how much weight the Carbondales will shave off your fatty after the break!

Carbon Rim Release 1

At the heart of the symmetric tubeless compatible rims is a double wall design the makes up the first carbon rims on the market. The rims are made with a pressure molded design for proper compaction and ultimate stiffness out of the double wall design. Measuring in at 85mm wide, the rims feature an aggressive bead hook for locking tires in place and currently use Stan’s rim tape, 60g of sealant, and a Stan’s tubeless valve. Borealis mentions that these are still pre-production and the tubeless system may evolve slightly fr production, but only in the name of making installation as easy ad possible.
Carbon Rim bike release photo 4
In our talks with folks about tubeless fatbike tires in the past, one of the main concerns was how you get this giant floppy tire to seat on a super wide rim. Borealis states that the tire is a tight enough fit that all you need to do is mount the tire with soapy water and inflate to around 25psi and it will seal without any additional work. Once the tire is locked in place it can be ridden at normal fatbike pressures without coming off the rim.
KHS-Fatbike-Vee-Rubber-Tubeless-mission Ready-Tires03
We spotted a pair of Vee Rubber Tubeless ready fatbike tires at Eurobike, so we know they’re coming. The interesting thing is that Borealis has been testing with standard, non tubeless 45nrth tires with success. While there isn’t an official word from them yet on using non tubeless fatbike tires tubeless, the initial outlook is good.
Borealis rim bike release photo 7
At 85 mm wide, the Carbondales are crazy light with early samples weighing 590 g without the internal construction bladder removed. Once the bladders are removed, they will likely reach their 550g target weight. Based on a comparative build with Surly Rolling Darryl rims and super light tubes, Borealis estimates that the entire tubeless system will still shave around 800g from the total rolling weight of the bike. Borealis also mentioned they expect one of their SL Yampa builds with standard parts and Carbondale rims should come in under 23lbs. Wow.
Borealis Bike with carbon rim release photo 6
Carbondale rims will only be offered in 32h drillings which will match up nicely with Borealis’ FH1 hubs, or any other fatbike hub for that matter. Borealis is just finalizing the production specs, with rims available for pre order through your local Borealis dealer or direct for $1599 per pair. Borealis hopes to be shipping by November.
Carbon Rim and bike release photo 3
More from Interbike!


  1. I don’t really get the fatbike craze. I guess i thought it was a cool novel idea back when surly had one, but now it seems like everone is pushing them… and now carbon fatbike rims? Crazy

  2. @Engineer: You will get the craze if you live where there is no other riding for half a year.

    And it is actually great for regular riding too. Try it.

  3. I run tubless all year round, no problems in the winter with stans. I have been out in -15 to -20 a few time. Cold toes and fingers are a bigger problem then the sealant.

  4. I have been riding my Fatback set up tubeless for the last 2 years, down to -30 F with no problems. Tubeless isn’t a new thing for fatties, Fatback bikes pioneered it with the Uma rims which have had a bead lock for tubeless setup for a couple of years now.

    And I agree with Mindless, I have 14 bikes in the garage, 13 of them share the summer and I ride the fat bike exclusively for the other 5 months of the year.

  5. I’m an armchair engineer and I have a bunch of objections about using carbon on rims this wide. I don’t know what they are, but I will do some reading on Wikipedia then come back here and give you all a [deleted] reason for why I’m right and you’re all wrong, including the true engineers who designed this wheel.

  6. Up in AK, people have been running all the Surly Fat Tires ghetto tubeless with much success for the past couple years; you just don’t want to deal with spraying sealant at -20 on the trail..

  7. @Mindless: You don’t have to run these tubeless. In fact, there are no true tubeless fatbike tires on the market yet, so this rim is at best a minor step up from “ghetto” tubeless setups.

  8. I’ve been riding my fatbike for nearly a year now, previously i’d ridden a 160mm travle all mountain bike for around 12 years. i live in the UK and since getting the fatty i’ve ridden nothing else, road, offroad, downhill, hard dry, soft wet, snow, sand, it copes with everything and… love the damn thing. You need to try for a couple of days to get it.
    its a Salsa Mukluk so not light weight but it still out climbs most people. Can’t wait to try the new light weight versions.

  9. Obscene price? Did you notice that they’re CF fatbike rims? If you think the price is obscene, don’t buy them. Note that you’re under no obligation to buy them, and exercising your free will and not buying them won’t hurt anyone’s feelings.

  10. This is the first “high end” fat bike rim. $800 gets you some VERY AVERAGE road bike rims if you’re talking carbon. They’re also close to half the weigth of aluminum rims. Try buying a frame that weighs half the weight of the frame you’re riding now and see how much that will cost you

  11. It was only a matter of time, what with folks like Derby over on mtbr doing wider (40-mm) carbon MTB rims.
    Funny though, as I’m more interested in the KHS fatbike shown in the article. This is the first time I’ve seen it.

  12. Carbon components on a bike with tires that are 4.5″, ha. What’s the point, tires will always be the heaviest part of the wheel. tubeless? who cares, still gonna get smoked by that random guy on a single speed clapped out piece of shit bike.

What do you think?