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Flume Select

Independence Day SALE - 20% OFF COMPLETE BIKES & FRAMES ENDS 7/15 - Discount automatically applied in cart!

0% APR up to 24 months with Affirm! Financing Options Available at Checkout.

$1,699.00 USD

Size Chart

bike size chart

Shipping and Returns

PO boxes not accepted.Shipping discounts or exclusions only apply within the lower 48 states of the US. Contact us if damage occurs during shipping. 

Borealis offers a 30-day money-back guarantee. If you are unsatisfied with your purchase for any reason, you can exchange your product or return it for a full refund minus any associated transaction fees and shipping costs. Customer is responsible for return shipping costs. Returned and exchanged items must be in sellable condition.




Original Owner
BOREALIS offers a LIMITED LIFETIME warranty to the original owner of each new BOREALIS bicycle, fork or frameset that the bicycle frame, fork or frameset when new is free of defective materials and workmanship.

Normal Conditions
The limited warranty is conditioned upon the bicycle being operated under normal conditions and use, and properly maintained.

This limited warranty does not apply to paint/finish or components attached to the bicycle/fork/frameset such as rims, drive train, brakes, seat post, handlebar and stem, or any suspension related parts or components.

Paint/finish, components attached to the bicycle/frameset such as rims, drive train, brakes, seat post, handlebar and stem, or any suspension-related parts or components are covered under the limited one (1) year warranty.

Load Weight
The total cargo load for BOREALIS frames and forks is 300 pounds. The total cargo load includes the rider and any associated gear warn by the rider or attached to the frame or fork.


Subject to the following limitations, terms and conditions, BOREALIS warrants to the original owner of each new BOREALIS bicycle that this bicycle, when new, is free of defective materials and workmanship. This warranty shall expire one (1) year from the date of the original purchase from an authorized BOREALIS dealer and is conditioned upon the bicycle being operated under normal conditions and use, and properly maintained. This warranty is void if the bicycle was not purchased new or not properly assembled by an authorized BOREALIS dealer.
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Customer Reviews

Based on 3 reviews
Dwight Sills

What an amazing bike! I love the feel, the handling, the look, and the light weight. I’m looking forward to hitting some trails (easy ones, because I’m 67 years old😉).

Robert Duzoglou
Beach Borealis

The order cam by quickly, as you know never quick enough but it was barely a week. Assembly from a non mechanic was actually fun and a learning education. Any adjustments that I now make are easily understood. The Quality of the product is WOW!!!!! Truly a beautiful piece of engineering. The ride has been incredibly enjoyable. The Beach riding is incredible, trails and road, great work out. Smooth and comfortable. Great investment, thank you!

Tony D.
Flume Select - Best bang for my buck

I wanted a fat bike primarily to ride the beach. I did quite a bit of research and decided on the Flume because of its quality components, light weight, and great price.

Living on the coast of Maine, we get our share of snow and ice. Continuing to ride my trail bike has become too dangerous at over 70 y/o. Because the tide cleans the beach of snow and ice twice a day, and of course no cars to deal with, riding conditions are very safe. The sand is pretty well packed at low tide so there aren't any issues riding atop the sand with the 3.8" maxis minions.

Last Sunday I wanted to see if I could ride the full length of the beach and back, 14 miles. It was the best ride of my biking life and the Flume preformed flawlessly.

Thanks for providing a great bike at an equally great price. The addition of the Flume adds variety to my biking. Now my hardest decision is whether to ride the fat or the trail bike.

The Flume Select provides unparalleled value for a fat tire bike. Perfect for riding in snow, sand, gravel, and everything in between. This fat bike combines our durable Aluminum Frame with our basic component build. Standard features include, Borealis Rigid Carbon Fork, SRAM Eagle NX 12-speed drivetrain, SRAM Level T Hydraulic Disc Brakes, SunRingle Mulefut 27.5" wheels and Maxxis Minion FBF/FBR 3.8" tires.

Frame Flume (Aluminum)
Fork Borealis Rigid Carbon 51mm Offset
Bottom Bracket SRAM DUB Threaded 100mm
Crankset SRAM Eagle NX Alloy 175mm w/ SRAM X-SYNC 30T
Rear Derailleur SRAM Eagle NX 12-Speed
Cassette SRAM PG-1230 11-50T
Shifter SRAM Eagle NX 12-Speed
Brakes SRAM Level T 2-Piston Hydraulic with SRAM Centerline 160mm Rotors
Headset FSA
Hubs Borealis GEN 4 Black 15x150 Front / 12x197 Rear
Rims Sun Ringle Mulefut V2 27.5x65
Spokes Borealis Straight Gauge
Nipples Borealis Silver Brass
Tires Maxxis Minion FBF/FBR 27.5x3.8
Bar RaceFace NEXT SL 740x10mm OR Borealis Carbon (based on supply)
Stem Borealis 50mm x 35mm
Post Borealis Carbon 31.6x400
Saddle Borealis
Grips Borealis
DT/CS Protector Lizard Skins
Estimated Weight Size Medium 30lb




Wheel / Tire Size 26 x 3.8–5.0" on up to a 100mm rim / 27.5 x 2.8-4.5 on up to an 82mm rim / 29 x 2.25–3.0
Max Fork Travel 120mm
Fork Offset 51mm
Headset-Upper IS41
Headset-Lower IS52
Seatpost ø31.6mm
Seat Collar ø34.9mm
Dropper Compatible Internal - 125mm for SM & MD / 150mm for LG & XL
Front Derailleur  Yes
Bottom Bracket 100mm Threaded BSA
Crankset (Max Ring) Chainline 76.5mm / 1x (34t)
Rear Brake (Rotor) 74mm post (160mm)
Rear Spacing 197 x 12mm thru-axle
Rear Axle ø12 x 229L, TP= 1.5, TL = 20
Derailleur Hanger Borealis Flume
Bottle Mount  Small & Medium: 1 (downtube) / Large & XL: 2 (downtube & seatube)
Rear Rack Reccomendation Old Man Mountain Divide Fat 
Rear Rack Mounts, Upper Yes
Axle to Crown 487mm
Steerer Tube Size 28.6mm
Steerer Style Tapered
Crown Seat Diameter 40mm





Stack and Reach are the fundamental fit elements, they are both measured relative to the bottom bracket. When choosing the Borealis that is right for you, it’s important to find a balance in these measurements to ensure the best performance.

  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
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



There is some assembly required upon receipt. Your bike will be completely assembled and tuned by Borealis, then partially disassembled for shipment. The remaining assembly will require installation of the rear derailleur, chain, fork, seat post, wheels, and handlebars. A multi-tool will be included with your order that has all tools necessary to assemble the bike, with the exception of a torque wrench. If you are not familiar with this level of assembly, we recommend having your local bike shop complete the assembly. Below is a video showing the remaining assembly once you receive the bike. Tires will be set up with tubes. Tubeless rim tape and valves are included on the side.

Assembly Video 

Download Owner's Manual

Check out our FAQ page for more information.


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