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Flume Custom - Aluminum Fat Bike Flume Custom - Aluminum Fat Bike
Flume Custom - Aluminum Fat Bike

With premium frame quality and only the best components, the Borealis Flume offers the best value on the market. This expedition-ready fatty mirrors the Crestone geometry, but does so in lightweight, 6000-series aluminum. Up mountains, down glaciers, and across deserts - the Flume is ready for action. There are all kinds of alloy fat bikes on the market, but none with the Flume’s purebred heritage and durability.

HIGHLIGHTS

  • Standard features include: SRAM Eagle NX 12-Speed drivetrain, SRAM Level T brakes, rigid carbon fork, carbon handlebars, carbon seat post, durable Sun Ringle Mulefüt rims and your choice of tires.
  • Frame geometry provides responsive handling, offering maximum control for varying conditions in snow or sand.
  • Tire clearance up to 26x5” and 27.5x4.5”.
  • Compatibility for 100-120mm of suspension travel for increased comfort and control.
  • Lightweight, 6000-series aluminum frame comes with 2-3 bottle cage mounts, rear rack mounts on seat stays and Lizard Skin protectors on both the down tube and drive-side chain stay.

    COMPATIBILITY

    • Rockshox Bluto Fork tire size limitations: 26x5” or 27.5x4”
    • Mastodon Pro EXT Fork tire size limitations: 26x5” or 27.5x4.5”
    • Borealis Rigid Carbon Fork tire size limitations: 26x5” or 27.5x4.5”
    • Dually 29x45 and 27.5x45 Rims – Max tire width: 3”
    • All rims 65mm to 85mm wide are compatible with tire widths of 3.8” to 5”
    • HED Carbon 100mm Rims – Max tire width of 4.8”

       

      ASSEMBLY

      If you choose "No Assembly" your bike will require complete assembly with an exception of the wheels. 

      If you choose "Assembled by Borealis", there is 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. A multi-tool will be included with your order that has all tools necessary to assemble the bike, with the exception of a torque wrench. If you are not familiar with this level of assembly, we recommend having your local bike shop complete the assembly. Below is a video showing the remaining assembly once you receive the bike. 

      Assembly Video

      WHEELS & TIRES

      • All bikes come standard with tubes.
      • If you order rim tape with your Mulefut rims, we will tape the rims and install the tires with tubes.
      • HED Alloy and HED Carbon rims do not require rim tape for tubeless set up.
      • Tubes must be removed and tubeless valves installed for tubeless set up. We recommended to have this completed by a professional bicycle mechanic.

      BUILD SPECS

      Eagle NX Eagle GX
      Frame Flume (Aluminum) Flume (Aluminum)
      Fork Borealis Carbon Rigid Fork Standard Option
      Bottom Bracket SRAM DUB 100mm
      Crankset SRAM Eagle NX Alloy 175mm w/ SRAM X-SYNC 30T SRAM Eagle GX Alloy 175mm w/ SRAM X-SYNC 30T
      Rear Derailleur SRAM Eagle NX 12 Speed SRAM Eagle GX 12 Speed
      Chain Eagle GX Eagle GX
      Cassette PG 1230 11-50 XG 1275 10-52
      Shifter SRAM Eagle NX SRAM Eagle GX
      Brakes SRAM Level T 2-Piston Hydraulic
      Rotors SRAM Centerline 160mm
      Headset FSA
      Hubs Borealis GEN 4 Black 15x150 Front / 12x197 Rear
      Rims Sun Ringle Mulefut V2 26x80 or 27.5x65
      Spokes Borealis Straight Gauge
      Nipples Borealis Silver Brass
      Tires Your Choice
      Bar Borealis Carbon 35x760mm
      Stem Borealis 50mm
      Post Borealis Carbon 31.6x400mm
      Saddle Borealis
      Grips Ergon GA20
      DT/CS Protector Lizard Skins
      Weight See weight calculator for estimated weight.

      SIZE CHART

      Based on our research, riders at the heights below will usually take the corresponding frame size. If you’re at a transitional height that spans two sizes, look at the geometry chart to get the Stack and Reach you like based on other bikes you are comfortable.

       

       

      GEOMETRY CHART

      Borealis offers four frame designs with unique fit and geometry to suit your every Fat Bike need. Begin by taking a rough size approximation on the chart below that is based on height, then select the corresponding bike with your fit needs by using the geometry chart further below. We recommend a similar fit to you mountain bike, so grab a measuring tape and dial it in.

        S M L XL
      EFFECTIVE TOP TUBE 585 mm 610 mm 630 mm 650 mm
      SEAT TUBE CENTER TO TOP 381 mm 432 mm 484 mm 534 mm
      HEAD TUBE 105 mm 120 mm 135 mm 150 mm
      SEAT TUBE ANGLE 73 deg 73 deg 73 deg 73 deg
      HEAD TUBE ANGLE 70 deg 70 deg 70 deg 70 deg
      STANDOVER HEIGHT Varies based on wheel and tire size
      CHAINSTAY 455 mm 455 mm 455 mm 455 mm
      BB DROP 60 mm 60 mm 60 mm 60 mm
      REACH 407 mm 423 mm 438 mm 451 mm
      STACK 597 mm 611 mm 625 mm 639 mm

      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 cancel, exchange, or return your product 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. Affirm transactions are subject to a 10% non-refundable transaction fee.

       

      $1,699.00
      Quick View
      Compare
      Flume Custom - Aluminum Fat Bike Flume Custom - Aluminum Fat Bike
      Flume Custom - Aluminum Fat Bike

      With premium frame quality and only the best components, the Borealis Flume offers the best value on the market. This expedition-ready fatty mirrors the Crestone geometry, but does so in lightweight, 6000-series aluminum. Up mountains, down glaciers, and across deserts - the Flume is ready for action. There are all kinds of alloy fat bikes on the market, but none with the Flume’s purebred heritage and durability.

      HIGHLIGHTS

      • Standard features include: SRAM Eagle NX 12-Speed drivetrain, SRAM Level T brakes, rigid carbon fork, carbon handlebars, carbon seat post, durable Sun Ringle Mulefüt rims and your choice of tires.
      • Frame geometry provides responsive handling, offering maximum control for varying conditions in snow or sand.
      • Tire clearance up to 26x5” and 27.5x4.5”.
      • Compatibility for 100-120mm of suspension travel for increased comfort and control.
      • Lightweight, 6000-series aluminum frame comes with 2-3 bottle cage mounts, rear rack mounts on seat stays and Lizard Skin protectors on both the down tube and drive-side chain stay.

        COMPATIBILITY

        • Rockshox Bluto Fork tire size limitations: 26x5” or 27.5x4”
        • Mastodon Pro EXT Fork tire size limitations: 26x5” or 27.5x4.5”
        • Borealis Rigid Carbon Fork tire size limitations: 26x5” or 27.5x4.5”
        • Dually 29x45 and 27.5x45 Rims – Max tire width: 3”
        • All rims 65mm to 85mm wide are compatible with tire widths of 3.8” to 5”
        • HED Carbon 100mm Rims – Max tire width of 4.8”

           

          ASSEMBLY

          If you choose "No Assembly" your bike will require complete assembly with an exception of the wheels. 

          If you choose "Assembled by Borealis", there is 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. A multi-tool will be included with your order that has all tools necessary to assemble the bike, with the exception of a torque wrench. If you are not familiar with this level of assembly, we recommend having your local bike shop complete the assembly. Below is a video showing the remaining assembly once you receive the bike. 

          Assembly Video

          WHEELS & TIRES

          • All bikes come standard with tubes.
          • If you order rim tape with your Mulefut rims, we will tape the rims and install the tires with tubes.
          • HED Alloy and HED Carbon rims do not require rim tape for tubeless set up.
          • Tubes must be removed and tubeless valves installed for tubeless set up. We recommended to have this completed by a professional bicycle mechanic.

          BUILD SPECS

          Eagle NX Eagle GX
          Frame Flume (Aluminum) Flume (Aluminum)
          Fork Borealis Carbon Rigid Fork Standard Option
          Bottom Bracket SRAM DUB 100mm
          Crankset SRAM Eagle NX Alloy 175mm w/ SRAM X-SYNC 30T SRAM Eagle GX Alloy 175mm w/ SRAM X-SYNC 30T
          Rear Derailleur SRAM Eagle NX 12 Speed SRAM Eagle GX 12 Speed
          Chain Eagle GX Eagle GX
          Cassette PG 1230 11-50 XG 1275 10-52
          Shifter SRAM Eagle NX SRAM Eagle GX
          Brakes SRAM Level T 2-Piston Hydraulic
          Rotors SRAM Centerline 160mm
          Headset FSA
          Hubs Borealis GEN 4 Black 15x150 Front / 12x197 Rear
          Rims Sun Ringle Mulefut V2 26x80 or 27.5x65
          Spokes Borealis Straight Gauge
          Nipples Borealis Silver Brass
          Tires Your Choice
          Bar Borealis Carbon 35x760mm
          Stem Borealis 50mm
          Post Borealis Carbon 31.6x400mm
          Saddle Borealis
          Grips Ergon GA20
          DT/CS Protector Lizard Skins
          Weight See weight calculator for estimated weight.

          SIZE CHART

          Based on our research, riders at the heights below will usually take the corresponding frame size. If you’re at a transitional height that spans two sizes, look at the geometry chart to get the Stack and Reach you like based on other bikes you are comfortable.

           

           

          GEOMETRY CHART

          Borealis offers four frame designs with unique fit and geometry to suit your every Fat Bike need. Begin by taking a rough size approximation on the chart below that is based on height, then select the corresponding bike with your fit needs by using the geometry chart further below. We recommend a similar fit to you mountain bike, so grab a measuring tape and dial it in.

            S M L XL
          EFFECTIVE TOP TUBE 585 mm 610 mm 630 mm 650 mm
          SEAT TUBE CENTER TO TOP 381 mm 432 mm 484 mm 534 mm
          HEAD TUBE 105 mm 120 mm 135 mm 150 mm
          SEAT TUBE ANGLE 73 deg 73 deg 73 deg 73 deg
          HEAD TUBE ANGLE 70 deg 70 deg 70 deg 70 deg
          STANDOVER HEIGHT Varies based on wheel and tire size
          CHAINSTAY 455 mm 455 mm 455 mm 455 mm
          BB DROP 60 mm 60 mm 60 mm 60 mm
          REACH 407 mm 423 mm 438 mm 451 mm
          STACK 597 mm 611 mm 625 mm 639 mm

          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 cancel, exchange, or return your product 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. Affirm transactions are subject to a 10% non-refundable transaction fee.

           

          $1,699.00
          Quick View
          Compare
          Crestone Custom - Carbon Fat Bike Crestone Custom - Carbon Fat Bike
          Crestone Custom - Carbon Fat Bike
          Since 2013, Borealis has specialized in lightweight carbon fiber fat bikes. 

            COMPATIBILITY

            • Rockshox Bluto Fork tire size limitations: 26x5” or 27.5x4”
            • Mastodon Pro EXT Fork tire size limitations: 26x5” or 27.5x4.5”
            • Borealis Rigid Carbon Fork tire size limitations: 26x5” or 27.5x4.5”
            • Dually 29x45 and 27.5x45 Rims – Max tire width: 3”
            • All rims 65mm to 85mm wide are compatible with tire widths of 3.8” to 5”
            • HED Carbon 100mm Rims – Max tire width of 4.6”

              ASSEMBLY

              If you choose "No Assembly" your bike will require complete assembly with an exception of the wheels. 

              If you choose "Assembled by Borealis", there is 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. A multi-tool will be included with your order that has all tools necessary to assemble the bike, with the exception of a torque wrench. If you are not familiar with this level of assembly, we recommend having your local bike shop complete the assembly. Below is a video showing the remaining assembly once you receive the bike.

              Assembly Video 

               

              WHEELS & TIRES

              • All bikes come standard with tubes.
              • If you order rim tape with your Mulefut rims, we will tape the rims and install the tires with tubes.
              • HED Alloy and HED Carbon rims do not require rim tape for tubeless set up.
              • Tubes must be removed and tubeless valves installed for tubeless set up. We recommended to have this completed by a professional bicycle mechanic.

                 

                SIZE CHART

                Based on our research, riders at the heights below will usually take the corresponding frame size. If you’re at a transitional height that spans two sizes, look at the geometry chart to get the Stack and Reach you like based on other bikes you are comfortable.

                 

                 

                BUILD SPECS

                Frame Flume (Aluminum)
                Fork Borealis Carbon Rigid Fork Standard Option
                Bottom Bracket SRAM DUB 100mm
                Crankset SRAM Eagle NX Alloy 175mm w/ SRAM X-SYNC 30T SRAM Eagle GX Alloy 175mm w/ SRAM X-SYNC 30T SRAM Eagle X0 Carbon 175mm w/ SRAM X-SYNC 30T SRAM Eagle XX Carbon 175mm w/ SRAM X-SYNC 30T
                Rear Derailleur SRAM Eagle NX 12 Speed SRAM Eagle GX 12 Speed SRAM Eagle X0 12 Speed SRAM Eagle XX 12 Speed
                Chain Eagle GX Eagle GX Eagle GX Eagle XX Gold
                Cassette PG 1230 11-50 XG 1275 10-52 XG 1295 10-52 XG 1299 10-52
                Shifter SRAM Eagle NX SRAM Eagle GX SRAM Eagle GX SRAM Eagle GX
                Brakes SRAM Level T 2-piston OR SRAM G2 RS 4-Piston Hydraulic
                Rotors SRAM Centerline 160mm
                Headset FSA
                Hubs Borealis GEN 4 Black 15x150 Front / 12x197 Rear
                Rims Sun Ringle Mulefut V2 26x80 or 27.5x65
                Spokes Borealis Straight Gauge
                Nipples Borealis Silver Brass
                Tires Your Choice
                Bar Borealis Carbon 35x760mm
                Stem Borealis 50mm
                Post Borealis Carbon 31.6x400mm
                Saddle Borealis
                Grips Ergon GP10
                DT/CS Protector Lizard Skins
                Weight See weight calculator for estimated weight.

                GEOMETRY CHART

                Stack and Reach are the fundamental fit elements, they are both measured relative to the bottom bracket. When choosing the Borealis that is right for you, it’s important to find a balance in these measurements to ensure the best performance.

                  S M L XL
                EFFECTIVE TOP TUBE 585 mm 610 mm 630 mm 650 mm
                SEAT TUBE CENTER TO TOP 381 mm 432 mm 484 mm 534 mm
                HEAD TUBE 105 mm 120 mm 135 mm 150 mm
                SEAT TUBE ANGLE 73 deg 73 deg 73 deg 73 deg
                HEAD TUBE ANGLE 70 deg 70 deg 70 deg 70 deg
                STANDOVER HEIGHT Varies based on wheel and tire size
                CHAINSTAY 459 mm 459 mm 459 mm 459 mm
                BB DROP 60 mm 60 mm 60 mm 60 mm
                REACH 407 mm 423 mm 438 mm 451 mm
                STACK 597 mm 611 mm 625 mm 639 mm

                 

                OWNER'S MANUAL

                Download Owner's Manual

                 

                 

                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 cancel, exchange, or return your product 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. Affirm transactions are subject to a 10% non-refundable transaction fee.

                 

                 

                $2,199.00
                Quick View
                Compare
                Crestone Custom - Carbon Fat Bike Crestone Custom - Carbon Fat Bike
                Crestone Custom - Carbon Fat Bike
                Since 2013, Borealis has specialized in lightweight carbon fiber fat bikes. 

                  COMPATIBILITY

                  • Rockshox Bluto Fork tire size limitations: 26x5” or 27.5x4”
                  • Mastodon Pro EXT Fork tire size limitations: 26x5” or 27.5x4.5”
                  • Borealis Rigid Carbon Fork tire size limitations: 26x5” or 27.5x4.5”
                  • Dually 29x45 and 27.5x45 Rims – Max tire width: 3”
                  • All rims 65mm to 85mm wide are compatible with tire widths of 3.8” to 5”
                  • HED Carbon 100mm Rims – Max tire width of 4.6”

                    ASSEMBLY

                    If you choose "No Assembly" your bike will require complete assembly with an exception of the wheels. 

                    If you choose "Assembled by Borealis", there is 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. A multi-tool will be included with your order that has all tools necessary to assemble the bike, with the exception of a torque wrench. If you are not familiar with this level of assembly, we recommend having your local bike shop complete the assembly. Below is a video showing the remaining assembly once you receive the bike.

                    Assembly Video 

                     

                    WHEELS & TIRES

                    • All bikes come standard with tubes.
                    • If you order rim tape with your Mulefut rims, we will tape the rims and install the tires with tubes.
                    • HED Alloy and HED Carbon rims do not require rim tape for tubeless set up.
                    • Tubes must be removed and tubeless valves installed for tubeless set up. We recommended to have this completed by a professional bicycle mechanic.

                       

                      SIZE CHART

                      Based on our research, riders at the heights below will usually take the corresponding frame size. If you’re at a transitional height that spans two sizes, look at the geometry chart to get the Stack and Reach you like based on other bikes you are comfortable.

                       

                       

                      BUILD SPECS

                      Frame Flume (Aluminum)
                      Fork Borealis Carbon Rigid Fork Standard Option
                      Bottom Bracket SRAM DUB 100mm
                      Crankset SRAM Eagle NX Alloy 175mm w/ SRAM X-SYNC 30T SRAM Eagle GX Alloy 175mm w/ SRAM X-SYNC 30T SRAM Eagle X0 Carbon 175mm w/ SRAM X-SYNC 30T SRAM Eagle XX Carbon 175mm w/ SRAM X-SYNC 30T
                      Rear Derailleur SRAM Eagle NX 12 Speed SRAM Eagle GX 12 Speed SRAM Eagle X0 12 Speed SRAM Eagle XX 12 Speed
                      Chain Eagle GX Eagle GX Eagle GX Eagle XX Gold
                      Cassette PG 1230 11-50 XG 1275 10-52 XG 1295 10-52 XG 1299 10-52
                      Shifter SRAM Eagle NX SRAM Eagle GX SRAM Eagle GX SRAM Eagle GX
                      Brakes SRAM Level T 2-piston OR SRAM G2 RS 4-Piston Hydraulic
                      Rotors SRAM Centerline 160mm
                      Headset FSA
                      Hubs Borealis GEN 4 Black 15x150 Front / 12x197 Rear
                      Rims Sun Ringle Mulefut V2 26x80 or 27.5x65
                      Spokes Borealis Straight Gauge
                      Nipples Borealis Silver Brass
                      Tires Your Choice
                      Bar Borealis Carbon 35x760mm
                      Stem Borealis 50mm
                      Post Borealis Carbon 31.6x400mm
                      Saddle Borealis
                      Grips Ergon GP10
                      DT/CS Protector Lizard Skins
                      Weight See weight calculator for estimated weight.

                      GEOMETRY CHART

                      Stack and Reach are the fundamental fit elements, they are both measured relative to the bottom bracket. When choosing the Borealis that is right for you, it’s important to find a balance in these measurements to ensure the best performance.

                        S M L XL
                      EFFECTIVE TOP TUBE 585 mm 610 mm 630 mm 650 mm
                      SEAT TUBE CENTER TO TOP 381 mm 432 mm 484 mm 534 mm
                      HEAD TUBE 105 mm 120 mm 135 mm 150 mm
                      SEAT TUBE ANGLE 73 deg 73 deg 73 deg 73 deg
                      HEAD TUBE ANGLE 70 deg 70 deg 70 deg 70 deg
                      STANDOVER HEIGHT Varies based on wheel and tire size
                      CHAINSTAY 459 mm 459 mm 459 mm 459 mm
                      BB DROP 60 mm 60 mm 60 mm 60 mm
                      REACH 407 mm 423 mm 438 mm 451 mm
                      STACK 597 mm 611 mm 625 mm 639 mm

                       

                      OWNER'S MANUAL

                      Download Owner's Manual

                       

                       

                      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 cancel, exchange, or return your product 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. Affirm transactions are subject to a 10% non-refundable transaction fee.

                       

                       

                      $2,199.00
                      Quick View
                      Compare
                      Keystone - Electric Fat Bike⚡ Keystone - Electric Fat Bike⚡
                      Keystone - Electric Fat Bike⚡

                        Introducing the all-new Keystone Electric Fat Tire Bike. Since 2013, Borealis has specialized in lightweight, high end fat bikes. The Keystone is our first ever Class I electric bike. The frame geometry is optimized for riding just about anything with clearance for up to 5” wide tires. Paired with the most technically advanced components in the industry, the Keystone sets the standard for premium quality Electric fat bikes. 

                      HIGHLIGHTS

                      • 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 and your choice of tires.
                      • 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.
                      • Keystone Frames are backed by our LIMITED LIFETIME WARRANTY.

                      ASSEMBLY

                      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. A kit will be included with your order that has all the necessary tools assemble your bike, including a multi-tool, torque wrench, and shock pump. If you are not familiar with this level of assembly, we recommend having your local bike shop complete the assembly. 

                      Stay tuned for our step-by-step assembly video. 

                      WHEELS AND TIRES

                      • All bikes come standard with tubes.
                      • If you order rim tape with your Mulefut rims, we will tape the rims and install the tires with tubes.
                      • Tubes must be removed and tubeless valves installed for tubeless set up. We recommended to have this completed by a professional bicycle mechanic.

                      SIZE CHART

                      BUILD SPECS

                      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
                      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.

                      FRAME SPECS

                      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

                       

                      GEOMETRY CHART

                      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

                       FAQ:

                      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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                      Keystone - Electric Fat Bike⚡ Keystone - Electric Fat Bike⚡
                      Keystone - Electric Fat Bike⚡

                        Introducing the all-new Keystone Electric Fat Tire Bike. Since 2013, Borealis has specialized in lightweight, high end fat bikes. The Keystone is our first ever Class I electric bike. The frame geometry is optimized for riding just about anything with clearance for up to 5” wide tires. Paired with the most technically advanced components in the industry, the Keystone sets the standard for premium quality Electric fat bikes. 

                      HIGHLIGHTS

                      • 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 and your choice of tires.
                      • 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.
                      • Keystone Frames are backed by our LIMITED LIFETIME WARRANTY.

                      ASSEMBLY

                      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. A kit will be included with your order that has all the necessary tools assemble your bike, including a multi-tool, torque wrench, and shock pump. If you are not familiar with this level of assembly, we recommend having your local bike shop complete the assembly. 

                      Stay tuned for our step-by-step assembly video. 

                      WHEELS AND TIRES

                      • All bikes come standard with tubes.
                      • If you order rim tape with your Mulefut rims, we will tape the rims and install the tires with tubes.
                      • Tubes must be removed and tubeless valves installed for tubeless set up. We recommended to have this completed by a professional bicycle mechanic.

                      SIZE CHART

                      BUILD SPECS

                      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
                      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.

                      FRAME SPECS

                      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

                       

                      GEOMETRY CHART

                      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

                       FAQ:

                      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.


                       


                      $5,999.00
                      Quick View
                      Compare