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Independence Day SALE - 20% OFF COMPLETE BIKES & FRAMES ENDS 7/15 - Discount automatically applied in cart!

0% APR up to 24 months with Affirm! Financing Options Available at Checkout.

$5,999.00 USD

Size Chart

bike size chart

Shipping and Returns

PO boxes not accepted.Shipping discounts or exclusions only apply within the lower 48 states of the US. Contact us if damage occurs during shipping. 

Borealis offers a 30-day money-back guarantee. If you are unsatisfied with your purchase for any reason, you can exchange your product or return it for a full refund minus any associated transaction fees and shipping costs. Customer is responsible for return shipping costs. Returned and exchanged items must be in sellable condition.


To the original owner, Borealis offers a limited lifetime warranty on all frames and rigid forks. All other Borealis branded components come with a 1-year limited warranty.

Weight limit for all frames, forks and components is 300 pounds. For more information, please view our Warranty/Return Policy.

Customer Reviews

Based on 7 reviews
Louis Panetta


Shawn Evans
Keystone is a super fun ride

Simple to assemble, this bike- out of the box, exceeds my expectations. From carving downhill tracks while climbing to speeding thru urban trails, the Keystone may become my regular steed of the quiver. The only change I want to make uockly is disabling the governor switch, although it doesn't really need it.

An amazing adventure bike!

As lifelong cyclists, we've owned & ridden mt bikes, gravel bikes, road bikes, fat bikes & tandems (both mtb & road).

A few years ago, we sold our mt bikes & have been loving doing all our year 'round trail riding on our lightweight, rigid fat bikes. Over the past few years, we talked about maybe "someday" looking at purchasing quality E-fat bikes... for when we "get old". There wasn't much out there that appealed to us for the wide range of riding we do, & we didn't think we were "old" enough to warrant E-Bikes yet.

Then, last summer, Borealis announced that they were coming out with the Keystone & we realized that we didn't need to be too "old" to ride our "analog" bikes before adding E-bikes to our lives. What excited us about the Keystone is the potential for greatly expanding our riding to routes that we'd decided to not do anymore. We ride for fun & once a route's work-to-fun ratio skews too far in the work direction, we drop it.

Short story: We are having so. much. fun riding routes that we'd relegated to the past, & have a growing list of routes we are eager to do again, or for the first time.

Long story: For our full demo reviews, check out our November 30 - December 5 reports on . We loved the bikes so much after the demo period, that we bought the Keystones & continue to discover more attributes every day.

Chris G.
No snow yet but my Keystone ⚡️is ready!!

When my pcp told me that I should consider riding pedal assist full time now due to a deteriorated hip I immediately started worrying about what was I going to do during the winter months. I started researching e-fatbike availability and found the Borealis Keystone. Decided to pull the trigger on Black Friday and received it on Dec 12th. Much quicker than I expected. The build quality is great! I have really enjoyed the geometry of the bike. It’s very comfortable. Feels like I could spend all day in the saddle. As I mentioned, no snow here in Southern NH yet but I’ve gotten in a good half dozen rides so far and the bike is just a blast. Finally, there is some snow in the forecast for the weekend so I’m hoping to get some miles in on the snow very soon. Having already owned another eMTB with the Shimano EP8 system, I was familiar with the capabilities of that. Pair that with an amazing Borealis frame design and giant 27.5 x 80mm wheels and you’ve got a year round fun machine. My only complaints are the stock saddle was terrible, there are just some imperfections in alignments of the motor cover which I’m hoping doesn’t cause water ingress long term and because of the down tube mounting battery, it suffers from the same slight battery latch sag that most bikes with the same design have. It’s all cosmetic and can easily be overlooked when you’re hooting and hollering while riding this great bike!

J Glass
Love this bike

This is the E-fat bike I’ve been waiting for, modern geometry and allowance for 5” tires.

Done quite a few rides now in the Tahoe area, this was yesterday on the Famous Flue trail with some lake riding also
Borealis Keystone E-Fat bike test on the Tahoe Flume trail


  • Frame geometry provides responsive handling, offering maximum control for varying conditions in snow or sand.
  • Tire clearance up to 26x5” and 27.5x4.5”.
  • Lightweight, 6000 series aluminum frame comes with internally routed cables, 1-2 bottle cage mounts and lizard skin protection.

    • Color: Gunmetal Grey with Cobalt Blue Graphics

    • Weight: 56 lbs. as shown.

    • Standard features include:
        Shimano EP8 Drive Unit
        Shimano 630Wh Battery
        SRAM G2 RS brakes
        Mastodon Pro EXT 120mm suspension fork
        Carbon handlebars
        Dropper seat post
        Durable Sun Ringle Mulefüt Rims
        Your choice of tires.

    Frame Borealis Keystone Aluminum 15", 17", 19", 21"
    Drive Unit Shimano DU-EP800
    Battery Shimano BT-E8036 (630Wh)
    Display Shimano SC-EM800
    Assist Switch Shimano SW-EM800L
    Speed Sensor Shimano EWSS300L540A
    Fork Manitou Mastodon PRO EXT 120mm, 51mm offset
    Headset FSA w/ Star Nut
    Stem Borealis 50mm or 70mm (Based on Supply)
    Handlebar Borealis Carbon 
    Grips Ergon GP1
    Saddle WTB Volt Medium Steel
    Seat Collar Borealis Bolt-On
    Seatpost KS Lev Integra 125mm (SM, MD) / 150mm (LG, XL)
    Brakes SRAM G2 RS
    Rotors SRAM HS2 200mm front / 180mm rear
    Shifter SRAM AXS Pod Contoller Right Bridge w/ MMX Clamp for GX Eagle Transmission
    Derailleur SRAM GX Eagle Transmission Derailleur
    Cassette SRAM GX Eagle Transmission Cassette 10-52T
    Chain SRAM GX Eagle Transmission Flattop Chain
    Crank Arms Samox 170mm
    Chainring Mount Samox 104 BCD for 75mm chainline 
    Chainring SRAM Eagle Transmission E-Bike MTB Chainring 104 BCD 36T Steel 
    Rims Your choice of SunRingle Mulefüt SL - 26x80, 27.5x80, or 27.5x65
    Spokes Straight Gauge 2.0 Black
    Hubs Borealis Gen 4 15x150 / 12x197
    Tires  Your choice. All tire options are listed online.
    Included Shimano ECE80042 Battery Charger, AXS Power Pack, Kickstand, UDH Hanger, Key for battery release, Borealis Rear Thru Axle, Remote Battery Charging Adapter
    Weight Size Medium w/ Mulefut 27.5x80 & Terrene Yippee Ki Yay 4.3" Tires: 56 lbs.

    Wheel / Tire Size 26 x 3.8–5.0" on up to a 100mm rim / 27.5 x 2.8-4.5 on up to a 82mm rim / 29 x 2.25–3.0
    Susp Fork Travel 120mm
    Fork Offset 51mm
    Headset-Upper IS41
    Headset-Lower IS52
    Seatpost ø31.6mm
    Seat Collar ø34.9mm
    Dropper Compatible Internal - 125mm for SM & MD / 150mm for LG & XL
    Front Derailleur Type Not Compatible
    Bottom Bracket Shimano EP8
    Crankset (Max Ring) Chainline 75mm / 1x (38t)
    Rear Brake (Rotor) 74mm post (160–180mm)
    Rear Spacing 197 x 12mm thru-axle
    Rear Axle ø12 x 222L, TP= 1.0, TL = 16
    Derailleur Hanger SRAM UDH
    Bottle Mount  Small & Medium: 1 (downtube) / Large & XL: 2 (downtube & seatube)
    Rear Rack Reccomendation Old Man Mountain Divide Fat 
    Rear Rack Mounts, Upper Yes
    Axle to Crown 531mm
    Steerer Tube Size 28.6mm
    Steerer Style Tapered
    Crown Seat Diameter 40mm

    Small 15" Medium 17" Large 19" X-Large 21"
    Effective Top Tube 630 645 660 665
    Seat Tube Center to Top 381 432 482 533
    Head Tube Length 160 160 175 190
    Head Tube Angle 69° 69° 69° 69°
    Seat Tube Angle 73° 73° 73° 73°
    Chainstay Length 480 480 480 480
    BB Drop 60 60 60 60
    Reach 420 435 445 446
    Stack 688 688 702 716
    Standover Height varies based on wheel and tire size
    Wheelbase 1187 1207 1223 1229
    Fork Offset 51 51 51 51

    Assembly Video

    Some assembly required upon receipt. Your bike will be completely assembled and tuned by Borealis, then partially disassembled for shipment. The remaining assembly will require installation of the rear derailleur, chain, fork, seat post, wheels, and handlebars.  If you are not familiar with this level of assembly, we recommend having your local bike shop complete the assembly. 


    Can I use the Keystone in cold temperatures?  It is okay to use your Keystone in the operating temperature range, suggest by Shimano: -10 - 50°C
    How do I remove the battery? Each Keystone will come with a set of keys. Make sure to save your spare key and safe location. Insert the key fully into the lock cylinder on the non drive side of the downtube until it stops.  Rotate the key clockwise until the battery drops from the downtube providing access to the latch release mechanism. Use your index finger to gently depress the spring which will fully release the battery. Use caution to support the battery when removing it so it does not fall to the ground. 
    How can I file a warranty claim for the drive unit and other electronic components?  Contact an authorized Shimano STEPS dealer.
    Can I change my motor/power settings?  Yes, you can customize your motor settings via the app as well as update the firmware. You'll need to download the Shimano E-tube mobile app.
    Can I change the max speed?  No. Depending on where you've purchased your Keystone it will either have a max assist speed of 20mph or 25km/h. This setting cannot be modified by the user or a dealer.
    Can I purchase an extra battery? Yes, you can purchase a spare battery kit with a spare downtube cover directly from Borealis. Spare battery kits may not be available in all markets. You can also purchase a spare battery from Shimano, but it will not include a battery cover.
    Can I ride the Keystone without the battery? No. This will void your warranty with Shimano and cause damage to the motor system.
    Do I need to update the firmware / software?  Firmware can be updated via the Shimano E-tube mobile app.
    How do I use walk mode?  Hold the upper button (down assistance level) for 1 second until the display turns blue and displays WALK mode. Press and hold the same button to power the rear wheel. 
    How long does it take to charge the Shimano 630Wh Battery?  With the included EC-E8004 charger, the battery can fully charge in 6 hours.
    How long will my battery last? The remaining battery capacity is affected by temperature and cycle count. Generally, it decreases approximately 5% a year. This means roughly 95% capacity remains after 1 year, and 90% after 2 years.
    How should I store my bike and or battery?  Charge your battery to approximately 70% before storing for long periods of time. Store in a cool, indoor location with a stable temperature between approximately 10 - 20 C / 50 - 70 F. No direct exposure to sunlight or rain.
    Are the electronic components waterproof?  Yes, the STEPS system is waterproof as long as all components of the system, including the battery and battery cover, are installed correctly. We recommend not using a high-pressure washer to clean your Repeater, but riding in the rain and regular cleaning are okay.
    My bike won't turn on, what do I do?  First, make sure all cables are plugged in, if they are then try removing and reinstalling the battery. If it still won't turn on try charging your bike for a few hours. If your bike is too hot or too cold, it might not turn on. If your bike still does not turn on, contact a Transition or Shimano dealer for support.
    Should I only charge my battery when it's completely drained?  No, simply charge the battery any time you need it, frequent charges actually help battery longevity. Avoid letting the battery discharge completely. Charge to 70% before storing for long periods.
    What are the different error codes and what do they mean?  Whenever you encounter an error code, first cycle the power off and then back on. If the code persists, remove the battery and then reinstall, which will hard reset the system. If neither of these steps resolves the issue, please reference the Shimano error code list. If you cannot resolve your error code via your Etube mobile app please visit your nearest Shimano STEPS dealer or contact Shimano STEPS customer support.
    What is the range and how can I maximize it?  There are many factors that affect battery range, such as, how much effort the rider is providing, the gradient of terrain, ambient temperature, and rider weight. The best way to maximize your range it to spend more time in Eco and Trail modes, and minimize the amount of time spent in Boost mode.
    What is the widest tire the Keystone can fit?  26x5.0" or 27.5x4.5"
    What kind of maintenance is needed on the drive unit and how often?  The drive unit is sealed and cannot be serviced. If there are any issues with the drive unit, it will need to be removed and sent back to Shimano for service or replacement. The drive unit along with the battery is designed to last over 1000 charge cycles. Assuming you're getting 30 miles (48Km) per charge, the drive unit should last 30,000 miles, or much longer than pretty much any other part on your bike.
    Why does my bike stop giving assistance over a certain speed?  Depending on where you've purchased your Keystone it will either have a max assist speed of 20mph or 25km/h. This setting cannot be modified by the user or a dealer.
    Will environmental temperature affect battery life?  The battery life will be shorter during cold temperatures, this is not a sign of a problem.
    Will my bike be delivered with a charged battery?  Your Keystone was shipped in a "sleep" mode with the battery at approximately 30% charge. It is recommended to fully charge your battery before the first ride.


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