The Flume Ultimate is specifically configured for riders looking for a capable, single-track-ready fat bike. This bike has all the features and capability for steep climbs and descents anywhere, anytime. Standard features include Manitou Mastodon Pro EXT 120mm Suspension Fork, SRAM Eagle GX 12-speed drivetrain, G2 RS 4-piston brakes, SunRingle Mulefut 27.5" wheels, Maxxis Minion FBF/FBR 3.8" Tires.
Frame | Flume (Aluminum) |
Fork | Manitou Mastodon Pro EXT 120mm or RockShox Bluto RL 100mm (based on supply) |
Bottom Bracket | SRAM DUB Threaded 100mm |
Crankset | SRAM Eagle GX Alloy 175mm w/ SRAM X-SYNC 30T |
Rear Derailleur | SRAM Eagle GX 12-Speed |
Chain | SRAM EAGLE GX |
Cassette | SRAM XG-1275 10-52T |
Shifter | SRAM Eagle GX 12-Speed |
Brakes | SRAM G2 RS 4-Piston Hyrdraulic 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 | KS Lev Integra w/ Southpaw Lever 125mm (SM, MD) or 150mm (LG, XL) travel |
Saddle | Borealis |
Grips | Borealis |
DT/CS Protector | Lizard Skins |
Estimated Weight | Size Large 33 pounds |
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 |
GEOMETRY CHART
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 |
ASSEMBLY
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.
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Customer Reviews
AWESOME RIDE. Easy to assemble. Great support staff.