Big Fat Dummy
Off-road Fat Tire Cargo Bike
$3175 USD / $4349 CAD
Surly Bikes
Bikes. Parts. Chaos.
Big Fat Dummy is a fat-tire, long-tail cargo bike that took a few too many doses of growth hormones.
All-Terrain, Fat Tire Trail Bike
Big Fat Dummy is truly a hulking beast of a bike. Maximalist bikepackers, those looking to make bikepacking a family affair, and those that help maintain their local trails will appreciate the Big Fat Dummy hauling abilities.
At first glance, it might just seem like a beefed-up version of Big Dummy, but that’s actually not the case. Specifically designed around fat tires, it has a longer toptube and slacker headtube offering the most stable, stiff, and predictable ride possible while hauling a lot of cargo.
- Single-piece frame increases stiffness and decreases torsional flex
- Human cargo compliant with the use of Dummy Rail Collars
- Three-pack mounts, double water bottle bosses on seattube, internal dropper post routing
- Clearance for 26" x 5.25" tires or 29” x 3.0” tires
Bike Capabilities
- 5/5 with Mixed Terrain Cargo Mixed Terrain Cargo: 5 out of 5
- 5/5 with Off-road Off-road: 5 out of 5
- 4/5 with Passengers Passengers: 4 out of 5
- 5/5 with Trail Building Trail Building: 5 out of 5
- 5/5 with Tire Clearance Tire Clearance: 5 out of 5
NOTE: You can ride your bike wherever the hell you want, but this is what we think this bike is best at.
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Where to Buy
Specifications
Frameset
| Frame |
Surly 4130 Chromoly steel. Main triangle double-butted. TIG-welded cargo specific engineered for stiffness and durability |
|---|---|
| Fork |
Surly Wednesday, Tapered straight blade 4130 Chromoly. 468mm axle to crown, 47mm offset. 51mm I.S. front standard disc mount, 150mm x 15mm thru-axle dropouts (axle included), 100mm suspension fork compatible |
| Seatpost Clamp | 33.1mm (Surly stainless included) |
Components
| Headset | Cane Creek 40 series |
|---|---|
| Brakes | SRAM Level T |
| Brake Levers | SRAM Level T |
| Rotors | SRAM Centerline 180/180mm |
| Shifters | SRAM GX 2x11 |
| Grips | Velo Single lock-on |
| Stem | 31.8mm clamp 4-bolt |
| Handlebar | Salsa Rustler |
| Saddle | WTB Volt |
| Seatpost | 30.9 2-Bolt 400mm |
Drivetrain
| Crankset | Race Face AEffect 34/24T |
|---|---|
| Bottom Bracket | Race Face |
| Front Derailleur | SRAM GX 2x11 high direct mount |
| Rear Derailleur | SRAM GX 2x11 type 2.1 |
| Cog or cogset | Sunrace 11 speed 11-42t |
| Chain | KMX X11 anti rust |
Wheels
| Front Hub | Novatec, 32h, Thru-Axle |
|---|---|
| Rear Hub | Novatec, 32h, Thru-Axle |
| Rims | WTB Scraper i40 ST TCS |
| Tires | Surly Dirt Wizard 29x3 60tpi |
Frameset
| Frame |
Surly 4130 Chromoly steel. Main triangle double-butted. TIG-welded cargo specific engineered for stiffness and durability |
|---|---|
| Fork |
Surly Wednesday, Tapered straight blade 4130 Chromoly. 468mm axle to crown, 47mm offset. 51mm I.S. front standard disc mount, 150mm x 15mm thru-axle dropouts (axle included), 100mm suspension fork compatible |
| Seatpost Clamp | 33.1mm (Surly stainless included) |
Components
| Headset | Cane Creek 40 series |
|---|---|
| Brakes | SRAM Level T |
| Brake levers | SRAM Level T |
| Rotors | SRAM Centerline 180/180mm |
| Shifters | SRAM GX 2x11 |
| Handlebar | Answer ProTaper |
| Grips | Velo Single lock-on |
| Stem | 31.8mm clamp 4-bolt |
| Saddle | WTB Volt |
| Seatpost | 9mm offset, 2-bolt |
Drivetrain
| Crankset | Race Face 36/22 |
|---|---|
| Bottom Bracket | Race Face |
| Front Derailleur | SRAM GX 2x11 high direct mount |
| Rear derailleur | SRAM GX 2x11 long cage type 2.1 |
| Cog or cogset | Sunrace 11s 11/42 |
| Chain | KMX X11 anti rust |
Wheels
| Front hub | Salsa 150x15 32h |
|---|---|
| Rear hub | Salsa 197x12 32h |
| Rims | Surly My Other Brother Darryl |
| Tires | Surly Edna 4.3 (front and rear) |
Complete bike spec subject to change
units:
| SIZE | SM | MD | LG |
|---|---|---|---|
| Reach | 16.1 408 | 17.0 432 | 17.6 448 |
| Stack | 22.8 578 | 23.5 597 | 24.6 625 |
| Head Tube Angle | 69.0° | 69.0° | 69.0° |
| Head Tube Length | 3.9 100 | 4.7 120 | 5.9 150 |
| Seat Tube Length | 14.0 356 | 17.0 432 | 20.0 508 |
| BB Drop | 2.2 55 | 2.2 55 | 2.2 55 |
| Wheelbase | 60.3 1532 | 61.5 1563 | 62.6 1590 |
| Chainstay Length | 34.4 875 | 34.4 875 | 34.4 875 |
| Top Tube Length, Actual | 23 584 | 23.5 598 | 24.3 617.3 |
| Top Tube Length, Effective | 23.2 590 | 24.4 620 | 25.4 645 |
| Seat Tube Angle | 72.5° | 72.5° | 72.5° |
| Standover Height | 29.4 746 | 31.2 792 | 33.1 841 |
| Stem Length | 2.4 60 | 2.8 70 | 3.1 80 |
| Stem Angle | 7° | 7° | 7° |
| Handlebar Width | 29.5 750 | 31.5 800 | 31.5 800 |
| Crank Length | 6.7 170 | 6.9 175 | 6.9 175 |
| Fork Length | 18.4 468 | 18.4 468 | 18.4 468 |
| Fork Rake | 1.9 47 | 1.9 47 | 1.9 47 |
| Frame Construction | 4130 Chromoly, Natch tubing, double-butted main triangle, trumpet flaired tubes, TIG welded |
|---|---|
| Fork Construction | 4130 Chromoly, Natch tubing, double-butted tapered fork blades, TIG welded, ED coated |
| Rear Dropout Configuration | Vertical |
| Rear Hub Spacing | 12 x 197mm (Surly axle included) 10 x 190mm with Surly 10/12 Adapter Washers (not included) |
| Front Hub Spacing | 15 x 150mm (Surly axle included) |
| Rear Brake | Disc - 51mm I.S. (203mm max rotor) |
| Front Brake | Disc - 51mm I.S. (203mm max rotor) |
| Head Tube | Ø44mm |
| Steerer Tube | Ø28.6mm (1-1/8") |
| Crown Race | Ø30mm (1-1/8") |
| Stock Headset Upper (S.H.I.S.) | ZS44/28.6 |
| Stock Headset Lower (S.H.I.S.) | EC44/30 |
| Seat Collar | Ø33.1mm |
| Seatpost | Ø30.9mm |
| Front Derailleur (Clamp) | High direct mount top-pull (Ø34.9mm) 55mm offset adapter (included) |
| Max Chainring (CL)[3] | No frame limitations |
| Bottom Bracket | 100mm threaded (1.37" x 24TPI) |
| Tire Clearance Frame [1]/[2] | 26 x 5.25" 29 x 3.0" |
| Tire Clearance Fork [1] | 26 x 5.25" 29 x 3.0" |
| Rigid Fork Spec | 468 x 47mm |
| Max Suspension Fork Length [4] | 511 x 51mm (Fatbike 100mm) |
| Bottle Mounts Frame | 2 Three-Pack (S) 2 Standard + 2 Three-Pack (M - L) |
| Bottle Mounts Fork | 2 Three-Pack |
| Rack Mounts Frame | Yes (Surly Dummy Rails) |
| Rack Mounts Fork | Yes (upper, lower, and mid-blade threaded) |
| Fender Mounts Frame | N/A |
| Fender Mounts Fork | N/A |
| Other Features | Kickstand plate Internal dropper post routing compatible |
[1] Different tire and rim combinations will result in different clearances.
[2] Depending on drivetrain configuration, tire clearance may be limited by the chain and not frame.
[3] Listed chainring clearance is worst case scenario. Clearances vary widely depending on components and configurations.
[4] Suspension fork length listed at full extension (not at sag)
FAQ & Reviews
Support
Downloads
- Surly Bike Sizing Chart
[pdf] - 308KB - Big Fat Dummy Framesheet
[pdf] - 863KB - Big Fat Dummy Fork Instructions (Wednesday Fork)
[pdf] - 164KB - Dummy Rail Collar Instructions
[pdf] - 555KB - Dummy Deck Instructions
[pdf] - 695KB - Dummy Rail Instructions
[pdf] - 672KB - Big Dummy/Big Fat Dummy Frame Insert Instructions
[pdf] - 122KB - Dummy Bag Instructions
[pdf] - 2.4MB - Universal Thru-Axle Instructions
[pdf] - 269KB - Wheel, Rim & Tire Instructions
[pdf] - 279KB - Bicycle Owner’s Manual (English)
[pdf] - 1.2MB
Frame Warranty
LIMITED WARRANTY
This Surly product is warranted against defects in materials and workmanship for three years from the date of retail purchase of the product, subject to the limitations detailed below. Save your dated receipt for proof of purchase.
This warranty does NOT cover the following:
- Damage due to improper assembly or follow-up maintenance or lack of skill, competence or experience of the user or assembler
- Products that have been modified, neglected, used in competition or for commercial purposes, misused or abused, involved in accidents or anything other than normal use
- Installation of components, parts or accessories not originally intended for or compatible with bicycle as sold
- Damage or deterioration to the paint, surface finish, aesthetics or appearance of the product
- Normal wear and tear
- Labor required to remove and/or refit and re-adjust the product within the bicycle assembly
This limited warranty is expressly limited to the repair or replacement of a defective product, at the option of Surly, and is the sole remedy of the warranty. This limited warranty applies only to the original purchaser of the Surly product and is not transferrable. This warranty applies only to products purchased through an authorized dealer or distributor. In no event shall Surly be liable for any loss, inconvenience or damage, whether direct, incidental, consequential, or otherwise resulting from breach of any express or implied warranty or condition, of merchantability, fitness for a particular purpose, or otherwise with respect to our products except as set forth herein.
This limited warranty gives the consumer specific legal rights, and those rights and other rights may vary from place to place. This limited warranty does not affect your statutory rights.
TO THE EXTENT NOT PROHIBITED BY LAW, THESE WARRANTIES ARE EXCLUSIVE AND THERE ARE NO OTHER EXPRESS OR IMPLIED WARRANTIES OR CONDITIONS INCLUDING WARRANTIES OR CONDITIONS OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.