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ORDER NOW! Current lead time is 3-4 weeks for complete bikes.

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

$6,500.00 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 1 review
Awesome fat tire e-bike.

I am extremely happy with my Keystone purchase. The bike fits me perfectly and it is so well balanced. Manuverability is great on mountain bike trails. I am 65 & overweight. The Keystone has enabled my to be able to ride with younger riders in better shape. I rode in the Bike Across SC in Rock Hill,SC. The first days route was 55 miles. I put the bike in eco to keep up with the pack & used boast mode to make it up some big hills. I finished the ride still with 2 bars out of 5. (Battery life is outstanding). The adaptive trail mode is awesome for a great ride on mountain bike trails. The bike is lightweight enough that it is easy to ride without using any battery assist, unlike my first e-bike which you had to use battery assist all the time as the bike was so heavy & I had to use 2 batteries to make a 60 mile ride. I have sold my other 2 bikes & the Keystone is the only bike I will ride on all terrains. So happy with my purchase.


  • 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

    Asssembly 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. 

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