Surly Big Fat Dummy

Name: Surly Big Fat Dummy
Brand: Surly

2017 UrbanUtilityLong-tail cargo

Suspension: Rigid
Wheels: 26″
Drivetrain: 2 × 11 22–36t / 11–42t
Gear range: 625%
Frame: Steel
Brakes: Hydraulic disc

Rider height by size (cm)

Size guide

SM 158–170
MD 168–179
LG 176–187

Components

16 of 20 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

Surly 4130 CroMoly steel. Main triangle double-butted. TIG-welded cargo specific engineered for stiffness and durability Not identified

Suspension

1 part

Fork
- Surly

Drivetrain

7 parts

Bottom bracket

100mm wide, threaded English (1.37˝ x 24t) Not identified
Cassette
- SunRace
Chain
- KMC X11 11 speeds
Crankset
- Race Face Aeffect 36/22t
Front derailleur
- SRAM GX
Rear derailleur
- SRAM GX 2x11 11 speeds
Shifters
- SRAM GX

Brakes

2 parts

Wheels and tires

4 parts

Cockpit and contact points

5 parts

Handlebar
- Answer
Headset
- Cane Creek Forty
Saddle
- WTB Volt
Seatpost

H.L. 9mm offset 2 bolt Not identified
Stem

H.L. 31.8mm clamp 4-bolt Not identified

Sizes and geometry

3 sizes Open in the geometry plotter

Enter your height to highlight matching ranges.

Size MD

Table

Reach 432mm

Stack 597mm

Wheelbase 1563mm

Head angle 69.0°

Seat angle 72.5°

Every size is drawn to the same scale, in millimeters. Explanatory schematic on an assumed 26″ wheel; exact published values are in the table below.

Size Reported by the manufacturer

Complete manufacturer geometry table 3 published sizes

Complete manufacturer geometry by size
Measurement
Reachmm	411	432	448
Stackmm	569	597	625
Top tube lengthmm	590	620	645
Seat tube lengthmm	356	432	508
Head tube lengthmm	90	120	150
Head tube angle	69°	69°	69°
Seat tube angle	72.5°	72.5°	72.5°
Chainstay lengthmm	875	875	875
Wheelbasemm	1532	1563	1590
Front centermm	661	692	719
Bottom bracket dropmm	55	55	55
Standover heightmm	740	790	840
Fork rakemm	47	47	47
Trailmm	72	73	72
Stack/reach ratio	1.38	1.38	1.40

Not published by the manufacturer: Bottom bracket height, 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: Steel
Fork material: Steel

Suspension

Suspension configuration: Rigid

Drivetrain

Derived by Bikelake

Front chainrings: 2
Smallest chainring: 22
Largest chainring: 36
Rear sprockets: 11
Smallest sprocket: 11
Largest sprocket: 42
Lowest gear: 13.6 in
Highest gear: 85.1 in

Wheels and brakes

Wheel configuration: Same size
Brake type: Hydraulic disc

Fit and controls

Seatpost: Rigid seatpost
Shifting: Mechanical

Additional specifications

Bottom bracket standard: BSA
Travel: Front: Additional specification: Not available: Yes
Rear: Additional specification: Not available: Yes
Wheel material: Aluminum
Wheel size: 26″

Gearing

Estimated speeds at 80 rpm

Lowest gear: 5.2 km/h
Highest gear: 32.6 km/h

Total gear range 625%

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.