This review comes after about 20 hours and 150 miles of trail riding. A vast majority of that riding took place in fresh snow because Northern Michigan got a heaping helping of December snow this year. I tried to get onto groomed trails as much as possible but even those were still fairly loose due to our snow conditions. You can check out my initial review of this wheelset for some background info.
Since we kept getting dump after dump of fresh, dry powder I spent a lot of time at, or below the recommended minimum pressure listed on the rims (6 psi). At first I was a bit paranoid about this because I wondered if I may burp the tire or screw something up. I didn’t have a single issue even when running about 2-3 psi with both my 45North Husker Du tires as well as Surly Bud and Lous. According to Adam Miller at Borealis this ability to run low pressures is due to the pronounced hook on the bead hook, and bead channel:
“I designed this hook system as something entirely new. The reason it is such a new design is because fat bike tires are not like mountain bike tires. Getting a tire to seal with no bead hook on a rim at 5psi is much different than a mountain bike tire at 20psi. Also, tire burps are more common at low pressures, let alone pressures around 6psi. So, the large hook and lock system provides the best way to fully encase the bead and hold the tire in place. It is nearly impossible to burp tires at low pressures with this design.”
My riding experience affirms the info from Adam. The rims made for the easiest tubeless setup I have ever run into for a fat bike and handled super low pressures without any issue. I started with 2 scoops of Stans sealant but needed to up that to 3 in order to get good sealing of the beads. The rims have a fairly low maximum pressure of 22 psi. If it takes more pressure than that you need to use more soapy water or some Uncle Dick’s Bead Slip. I found about 20 psi and soapy water worked well for seating my tires. I can’t say if it is the big bead hook or the snug fit of the tires on the rims but tires did seal up very quickly when switching between different sets. This could be a significant advantage on race morning if you need to swap out tires based on changing snow conditions.
According to Adam the minimum listed pressure is for summer riding in order to avoid extreme rim hits:
“We’ve gotten some pretty gnarly rim hits with no issues, but in aggressive mountain biking at low pressures rim hits could be an issue for the bigger guys. We designed these rims to be burly and capable of all around mountain biking, so they are not fragile by any means. But, due to the nature of the low tire pressure in fat biking, we wanted to ensure that these rims wouldn’t be getting continuously smacked on rocks.”
I can’t back up the rim hit durability too much because we just had too much powder to hit much hard stuff. I did bottom the tire on the rim from hitting an occasional buried chunk of wood or ice on downhills. Even though I got a muted thud from the impact, I couldn’t find any marks on the rim or tire after the ride.
The overall durability of the wheels was excellent (as would be expected) over my fairly short testing period. The wheels maintained their spoke tension and trueness. The hubs still spun just as smoothly as the day I got them. I ran into zero issues with the freehub or bearing drag even in single digit temperatures. I ran my Gates belt drive for a single ride with only slightly discernible marking on the freehub body. Indications are good that the alloy freehub body will hold up ok when used with cogs that have a reasonably thick base.
In powdery conditions the ability to run extremely low pressures was nice and the rims did seem to build up less snow than “holey” rims that have more texture. Sometimes I got a lot of snow buildup on the rims but as the pics show below, there were other snow conditions where very little built up compared to holey metal rims.
It wasn’t until I was able to ride the wheels after a thaw/freeze cycle that the greatest aspects of the wheel (lightweight) really made a huge difference. I lucked out and on the last day of testing we got the perfect fat biking conditions with hard pack, grippy trails. In these conditions I was looking for any bump, berm or other feature to play on. With wheels this light your bike just feels more playful and it is tough to not have your mindset change such that you are constantly scanning for things to ride up, rail around or hop over. Rides go from tours through a winter wonderland to an amusement park ride. So many times I felt like I was on a pumptrack tossing around a lightweight pizza cutter bike but at the time I was rolling on big meaty 4.8” tires. Wheel stiffness is hard to gauge in the snow with fat tires but all indications are that this is a very stiff wheelset because the bike handled wonderfully when pushed hard.
It is almost impossible to convey how much a two pound drop in rim/tire weight does to the feel and playfulness of a fat bike. The old adages of “a pound saved on the wheels is worth three pounds on the frame” kept coming to mind while I rode this wheelset. I can safely say that switching to a wheelset like this will dramatically improve the ride of almost any fat bike making it feel considerably faster and more fun to ride. This wheelset is a game changer.
If you are interested in getting a set of wheels like this you should talk to your local Borealis dealer. A dealer listing is available at the Borealis site. You can have your dealer send in an existing set of hubs to be built up by one of their two expert wheel builders or you can purchase hubs such as the Industry Nine hubs I used.
More information about the Borealis Carbondale rims is available at Borealisbikes.com.
More information about the Industry Nine hubs is available at Industrynine.net.