I’ve never written a review before, but lets give this a shot.
My journey started with a my buddy buying an analog fatty and encouraging me into following him. I’m 63 years old, live at 8,400ft elevation in Eastern Sierra, been riding eMTN bike several times a week for just over a year, and it seams like everything I ride is uphill. I tried my buddy’s bike and I could not climb my normal route (1,000ft/7miles). I began researching fatty eMTN bike and quickly found Borealis Keystone. I lamented for several weeks and pulled the trigger early November 2024.
I had questions on choosing the right tires/wheels. The staff was very helpful discussing my riding style/needs and helping me select the right combination (26”, 4.8”).
The bike arrived 3 weeks later (delayed at my request d/t travel). It was meticulously packed and I assembled it on my workbench/clamp. It took about 4 hours (I’m kind of slow and it was the first time. I had not changed my own tire in 50 years). I called the shop for assistance in assembling/sequencing the rings at the head tube. They were quite helpful and got me back on track. I was surprised to learn the bike did not include pedals and it took me several days to acquire some. [Recommendation to Borealis, give options to choose pedals/opt out during the purchase process, just like tires and wheels].
This bike has exceeded every expectation. It handles soundly. Shifting and breaking were flawless without any user adjustments. I can travel uphill/downhill with confidence.
Regarding the battery/range. My ride last week (1hr:43min, 2,746ft elevation gain, and 14 miles) left me using 40% of the battery. I failed to charge that night. I followed this with a longer/steeper ride/climb (3 hrs, 3,865ft, 25 miles) and ran my battery dry in the last 1/2 mile. I mostly ride in ECO mode and occasionally use TRAIL and seldom use BOOST. I can conclude that if you need more than 5 hrs and 6,600 elevation gain, and 40 miles, on 3-5 psi, then you might consider carrying an additional battery.
Regarding versatility, during these two rides above, I traveled on snow, ice, sand, rock garden, slush, hard pack road base, gravel, asphalt, and 12” deep creek. During these two rides, I only lost control when crossing the creek and found an unexpectedly deep rut. This caused me to step off my bike. On other rides, I went down when hitting ice as I did not opt to put studs in the tires (live and learn).
There is truly no terrain this bike cannot handle (however, I recommend considering studs for ice, I have not tried this option).
Today, I noticed my rear brake was soft and the lever pulled back to the bar. I had to stop my ride. I’ll take it locally for a bleed tomorrow morning and hope to ride in the afternoon.
If you want to HAVE A BLAST on the mountain or just want to expand your riding season to 12 months a year, this bike is for you!
Customer Reviews
These might not be able to handle the rigors of bikepacking and/or rough terrain, especially the rear wheelset on a wide (fat) hub. I bought them to adapt a Kona fat bike to 27.5 x 3” tires to bikepack the Iceland Divide. It’s about 350 miles across the Iceland highlands. ( https://bikepacking.com/routes/iceland-divide/) . Granted, it’s not an easy trip, but the total weight of bike and gear was probably about 120-140 kg. Prior to Iceland, I tested the set up with two multiday trips in Oregon, the Central Oregon Backcountry Explorer, and the Anaxshat Passage – each about 120-200 miles on gravel, carrying about 4 days of gear and food. They did great on those shakedown rides.
The first two spokes broke on Day-2 in Iceland, on a basic gravel road, after having about 400 miles total on the rear wheel. I managed to taxi back to Akureyri and get those fixed. After about 7 more days riding two more spokes broke (after going over lava, sand, wind, rain, thousands of feet elevation, etc). That would be about 650 miles into the total wheel mileage. I finished the last two days hoping I wouldn’t break more.
In total, it broke three on the non drive side and one on the drive side over about 400-650 miles of bikepacking.
I think more spokes would have failed except for some changes in terrain and technique. I moved most weight toward the front. The front rim didn't break any spokes. On the big uphills, i pushed the bike, and slowed down in the really bumpy downhills to keep the stress down. The terrain at the beginning of the divide was much rougher than the last half. The southern half was more like typical gravel roads with washboards and embedded rocks (plus about 30+ river crossings)
The rear hub on a fat bike is much wider than the front. The spokes might be stressed between a 45mm rim and a wide hub. The rear hub where the spokes connect is 110mm while the front is 100. I theorize that some spoke flexing caused them to fail. They all failed at the nipple.
I'll look into re-spoking, maybe with stronger spokes. There is a slight wobble in the rear wheel now, but i think a full re-spoke can bring it into alignment. The rim seemed strong, even handling extra mileage, terrain, and weight after losing two more spokes with over a hundred more miles to go. I'm still worried about the nipple alignment with the wider fat bike hub and whether I should every trust them in the backcountry again.
This was a special situation for me, and probably for these wheels -- adapting a 45mm rim to a fat bike so I could run 3" tires in Iceland. The lava, river crossings, deep gravel and sand really needed the fatter tires ( >2.4), but didn’t call for 4" - 5" tires typical of fat bikes. So I adapted my fat bike to narrower rims and tires to do this kind of trip. My wife rode a salsa timberjack with 27.5 x 3". But her hubs were "boost”, not fat. The spokes are not under that “wide angle” stressing like mine seem to be.
A couple photoes show the angle of the spokes and the breakage at the nipple.
Fair price, good quality.
Picked up two sets of these and both sets were built fast and already prepped for tubeless tires (w/valves and taped). Tires seated easily and wheels have been perfect so far. Customer service was top notch as well. Highly recommended.
I bought the 29er version. They're everything a great wheelset should be - strong, stiff, true, and quiet. And my tubeless tires mounted fine with no leaks. The Borealis hubs are great too! Quiet and smooth. Thanks!
Everything is great