A perfect compliment to their forthcoming Yampa carbon fatbike, Borealis has just revealed their new fatbike FH1 hubs which include a number of firsts. We’ve heard the new standard for fatbikes may increase in the rear to 190mm, which is exactly what Borealis is using. Combine that with one of the first front specific, 135mm symmetrical, 15mm thru axle hubs and you have the recipe for an extremely stiff bike with room for the biggest tires around.

Details on the new hubs after the break.


In order to keep the hubs as versatile as possible, not only is the front hub convertible between QR15 and standard quick release, but the free hub is convertible between a standard 9/10 and XX1 compatible XD driver. The conversion can be done on the rear hub with only 2, 5mm allen wrenches while the front hub conversion needs no tools at all.

Borealis_Freehub_Body Borealis_Rear_Hub_Internals

The freehub on FH1 hubs includes a 6 pawl mechanism with a 24t drive ring for an impressive 144 engagement points.


The front hub uses front disc tab spacing, meaning a front disc brake adapter will be needed if it’s not used on the post mount Yampa fork. FH1 hubs roll on high quality sealed bearings front and rear, with the rear a standard 4 bearing design – two in the body, two in the freehub. Even with how wide the hubs are, they are still impressively light at 193g for the front and 359g for the rear. FH1 hubs will be available in both black and red anodized finish with laser etched Borealis graphics, both only in 32 hole drillings. The hubs will retail for a surprisingly low $349 per set.


  1. Aha – 190mm – way cool


    why should I use 15mm axle on the front with 135 mm


    QR in the back – where all the weight is – with 190mm


    Come on guys do it once and do it right



  2. Martin,

    Lots of reasons.

    1) 15mm is the thru axel standard in thru axels
    2) 135mm front’s are the standard for fat bikes
    3)QR in back….still a standard. and QR’s are available.
    4) Custom thru axel on the rear is spendy with 190mm being a new standard it’s yet to be seen if needed….especially on a hard tail. FYI-silly on most any hardtail but only reason you’re starting to see it on normal hardtails is the standard (and parts) are already in place it makes it easy.

  3. Badass! Well said Sevo. Can’t argue with logic!

    Also, 144 points of engagement is kick ass for a fat bike, no slamming into engagement! Right on!

  4. @Sevo
    The are no fixed fatbike standards – it’s an evolving process. How many 190mm production frames exist? How many 135 TA forks exist? 190 already requires custom hubs – why would a custom axle be much more work? A Hope ProII setup is in this price range anyways, and they have every axle configuration under the sun available, so cost isn’t an issue. QR/TA – who cares – it doesn’t matter for fatbikes anyways. How much better would my moonlander ride with 190QR rear /135 TA front? Not an amount I would be able to detect.

  5. Makes sense to me for Fat bikes to go thru axle. You are leveraging a wider wheel, hub and bigger tire. I know I noticed a huge difference going from a Niner QR carbon fork to thier TA RDO version (fits on Krampus!). The Moonlander isn’t setting any records for handling or weight but when this applies to a 23 lbs carbon Borealis you have a whole different story.

  6. Probably the reason for a stiffer axle up front is because fork legs are flexy in comparison to the rear of a bike. Fork legs can twist pretty easily. On the other hand the combination of chainstay and seatstay on the rear of the bike means that the rear axle mounting location is torsionally stiff.

    Also, with fat suspension forks coming out soon, the need for a stiff front axle will increase and 15×135 will likely be the standard. If greater stiffness is needed in the rear, it is likely that a solid 9mm conversion axle will appear on the market.

  7. Nice looking hub. It looks durable. I’d like to make a correction to the article. This hub does not have 144 points of engagement. I see that the drive ring has 24 teeth. If the 6 pawls all engaged at the same time you would have 24 points of engagement. If the 24 teeth were matched with 6 pawls that were all clocked at an angle in which they did not engage at the same time then you could get 144 engagement points. But that would also mean that only one pawl engages at a time, which would likely lead to early failure. I can see that the 6 pawls are clocked in sets of 3 so only 3 pawls engage at a time. Each set of 3 pawls engages at 1/2 the distance between drive ring teeth, which in effect doubles the engagement from 24 to 48. 48 is pretty good, but far from 144. Another way to look at is 360 degrees divided by 48 = 7.5 degrees between engagement. For comparison a Chris King hub has an engagement of 360/72 = 5 deg.

What do you think?