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.

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.

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.

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.

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.

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