2021/2022 Borealis Flume Fat Tire Bicycle
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!
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.
- 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.
- 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”
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|
|Fork||Borealis Rigid Fork or RL Bluto, Mastodon Pro Ext.|
|Hubs||Borealis: Front 15×150 Rear 12×197|
|Nipples||Wheelsmith Silver Brass|
|Bar||Borealis Carbon Bar (35mm)|
|Stem||Borealis 50mm or 70mm|
|Post||Borealis Carbon Seatpost (31.6mm)|
|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.
|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|