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.
- 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
- 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.
|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|