The Borealis Flume offers the best fat bike 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 carbon 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.
- Available in two colorways
- Reduced stand over height
SPECS
- Chainstay and seatstay protectors
- Seatpost collar
- Rear axle and derailleur hanger
Frameset includes all of the above as well as:
- Complete headset and compression plug/ star nut
- Front axle
- Fork of your choice
All frames are covered by a 5 year warranty and crash replacement program.
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 | |
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 |
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