Borealis Flume Custom Build

Name: Borealis Flume Custom Build
Brand: Borealis

2023 MountainFat bike Manufacturer page

Last known price: $1,699

Prices shown first for United States
Suspension: Rigid
Wheels: 26″
Drivetrain: 1 × 12 30t / 11–50t
Gear range: 455%
Frame: Aluminum
Brakes: Hydraulic disc

Rider height by size (cm)

Size guide

SM 157.5–167.6
MD 165.1–177.8
LG 175.3–188
XL 185.4–195.6

Components

18 of 21 identified

Parts found in a manufacturer catalog show their brand, model and key numbers, and the steps show how precisely they are identified: brand, series, model, or the exact product. The info button has every detail and the text the manufacturer published.

Frame and fork

1 part

Frame

Flume (Aluminum) Not identified

Suspension

1 part

Fork
- Borealis

Drivetrain

6 parts

Brakes

2 parts

Wheels and tires

5 parts

Front hub
- Borealis
Rear hub
- Borealis
Rims

Sun Ringle Mulefut V2 26x80 or 27.5x65 Not identified
Spokes
- Borealis
Tires

Your Choice Not identified

Cockpit and contact points

6 parts

Sizes and geometry

4 sizes Open in the geometry plotter

Enter your height to highlight matching ranges.

Size MD

Table

Geometry diagram unavailable

The drawing needs wheelbase, which the manufacturer did not publish. Available facts remain in the table.

Size Reported by the manufacturer

Complete manufacturer geometry table 4 published sizes

Complete manufacturer geometry by size
Measurement
Reachmm	407	423	438	451
Stackmm	597	611	625	639
Top tube lengthmm	585	610	630	650
Seat tube lengthmm	381	432	484	534
Head tube lengthmm	105	120	135	150
Head tube angle	70°	70°	70°	70°
Seat tube angle	73°	73°	73°	73°
Chainstay lengthmm	455	455	455	455
Bottom bracket dropmm	60	60	60	60
Bottom bracket heightmm	283	283	283	283
Stack/reach ratio	1.47	1.44	1.43	1.42

Not published by the manufacturer: Wheelbase, Front center, Standover height, Fork rake, Trail, Front travel, Rear travel, Crank length, Handlebar width, Stem length, Stem angle, Seatpost length and Dropper post travel.

Specifications

Frame and fork

Intended fit: Unisex
Frame material: Aluminum
Fork material: Carbon

Suspension

Suspension configuration: Rigid

Drivetrain

Derived by Bikelake

Front chainrings: 1
Smallest chainring: 30
Largest chainring: 30
Rear sprockets: 12
Smallest sprocket: 11
Largest sprocket: 50
Lowest gear: 15.6 in
Highest gear: 70.9 in

Wheels and brakes

Wheel configuration: Same size
Brake type: Hydraulic disc

Fit and controls

Seatpost: Rigid seatpost
Shifting: Mechanical

Additional specifications

Travel: Front: Additional specification: Not available: Yes
Wheel material: Aluminum
Wheel size: 26″

Gearing

Estimated speeds at 80 rpm

Lowest gear: 6.0 km/h
Highest gear: 27.2 km/h

Total gear range 455%

Technical details and class reference

These speeds describe the gearing at the selected cadence, not how fast you can ride.
Calculated from published gear-inch values and their wheel-size assumptions.
These gearing values describe the bicycle, not a selected frame size.
A 100% range means one ratio; 500% means the highest ratio is five times the lowest.
For e-bikes, motor assistance cutoff is not represented.

Gear-inch range

Lower gear-inch values travel less distance per pedal revolution; higher values travel farther.

This bicycle: 15.6–70.9 gear inches

Lineup changes

The published facts that differ across this family's builds and from the same model a year earlier. Missing information never counts as zero.

Differences across 2023 builds

Differences across 2023 builds
Specification	This bicycle Borealis Flume Custom Build	Borealis Flume Custom Build Eagle	Borealis Flume Elite	Borealis Flume Select	Borealis Flume Ultimate
Frame
Fork material	Carbon	Carbon	Carbon	Carbon	Not informed
Bicycle weight	Not informed	Not informed	12.7 kg	13.61 kg	14.97 kg
Suspension
Suspension configuration	Rigid	Rigid	Rigid	Rigid	Hardtail
Front travel	Not informed	Not informed	Not informed	Not informed	120 mm
Drivetrain
Front chainrings	1	Not informed	1	1	1
Smallest chainring	30	Not informed	30	30	30
Largest chainring	30	Not informed	30	30	30
Smallest sprocket	11	11	10	11	10
Largest sprocket	50	50	50	50	52
Lowest gear	15.6 in	Not informed	15.6 in	15.6 in	15.0 in
Highest gear	70.9 in	Not informed	78.0 in	70.9 in	78.0 in
Brakes
Brake type	Hydraulic disc	Mechanical disc	Hydraulic disc	Hydraulic disc	Hydraulic disc
Cockpit
Seatpost	Rigid seatpost	Rigid seatpost	Rigid seatpost	Rigid seatpost	Dropper seatpost
Other specifications
Suspension	Rigid	Rigid	Rigid	Rigid	Hardtail
Bottom bracket standard	Not informed	Not informed	BSA	BSA	BSA
Tire width	Not informed	Not informed	4″	3.8″	3.8″