2021/2022 Borealis Flume Fat Tire Bicycle

Borealis Bikes

  • $ 2,900.00
    Unit price per 
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Only 1 left!

Current Stock: (08/21):

We received a light batch of Borealis Flumes! Kits may vary depending on what's available. Please give us a call today!

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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

  • Traditional fat bike geometry is both responsive and nimble for variable conditions in snow or sand.
  • Standard features include: Eagle NX 12-Speed drivetrain, rigid alloy fork, carbon handlebars, carbon seat post and durable Sun-Ringle Mulefut rims.
  • 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 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”

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SPECS

Eagle 12 speed Flume Specs (1×12)

 

Eagle NX Eagle GX Eagle XO Eagle XX
Crankset SRAM Eagle NX SRAM Eagle GX SRAM Eagle XO SRAM Eagle XX
Crank Arms 175mm Alloy 175 Alloy 175mm Carbon 175 Carbon
Rear Derailleur RD ENX 1 x 12 RD EGX 1 x 12 RD EXO 1 x 12 RD EXX 1 x 12
Chain KMC X12 KMC X12 KMC X12 SRAM X12 Gold
Cassette PG 1230 11-50 XG 1275 10-50 XG 1295 10-50 XG 1299 10-50 Gold
Shifters SRAM ENX SRAM EGX SRAM EXO SRAM EXX
Brakes SRAM - Select SRAM - Select SRAM - Select SRAM - Select
Chain Ring 30 Tooth
Frame Borealis Alloy
Fork Borealis Rigid Fork or RL Bluto, Mastodon Pro Ext.
Headset Borealis
Hubs Borealis: Front 15×150 Rear 12×197
Rims Your Choice
Spokes Wheelsmith Black
Nipples Wheelsmith Silver Brass
Tires Your Choice
Bar Borealis Carbon Bar (35mm)
Stem Borealis 50mm or 70mm
Post Borealis Carbon Seatpost (31.6mm)
Saddle Borealis
Grips Borealis
Bottom Bracket SRAM DUB 100mm
DT/CS Protector Lizard Skins
Weight See weight calculator for exact weight.


RIDER HEIGHT RECOMMENDATIONS

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 & SIZING

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 S M L XL
EFFECTIVE TOP TUBE 23.02 in 24.02 in 24.8 in 25.59 in 585 mm 610 mm 630 mm 650 mm
SEAT TUBE CENTER TO TOP 15 in 17.01 in 19.06 in 21.02 in 381 mm 432 mm 484 mm 534 mm
HEAD TUBE 4.13 in 4.72 in 5.31 in 5.91 in 105 mm 120 mm 135 mm 150 mm
SEAT TUBE ANGLE 73 deg 73 deg 73 deg 73 deg 73 deg 73 deg 73 deg 73 deg
HEAD TUBE ANGLE 70 deg 70 deg 70 deg 70 deg 70 deg 70 deg 70 deg 70 deg
STANDOVER HEIGHT Due to various rim and tire options stand over is not identified.
CHAINSTAY 17.91 in 17.91 in 17.91 in 17.91 in 455 mm 455 mm 455 mm 455 mm
BB DROP 2.36 in 2.36 in 2.36 in 2.36 in 60 mm 60 mm 60 mm 60 mm
REACH 16.04 in 16.65 in 17.22 in 17.76 in 407.3 mm 423 mm 437.5 mm 451.2 mm
STACK 23.50 in 24.05 in 24.61 in 25.16 in 597 mm 610.9 mm 625 mm 639.1 mm