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:

Please view our SUPPORT page to see the remaining assembly that is involved if you choose "Assembled by Borealis" in the build & price tool.

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.
• 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.

SPECS

Eagle 12 speed Flume Specs (1×12)

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.