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2021 Big Fat Dummy - 29"-Surly-Thorfrost White-Small-Uptown Bicycles
2021 Big Fat Dummy - 29"-Surly-Uptown Bicycles
2021 Big Fat Dummy - 29"-Surly-Uptown Bicycles
2021 Big Fat Dummy - 29"-Surly-Uptown Bicycles
2021 Big Fat Dummy - 29"-Surly-Uptown Bicycles


2021 Big Fat Dummy - 29"

The Big Fat Dummy is a long tail cargo bike designed around big tires to create the most stable, stiff, and traction-laden ride possible, while riding fully-loaded on a varied terrain. All Big Fat Dummy bikes ship with a Dummy deck, rails, bags, and Dummy Rail Collars.

  • 100% Surly 4130 Chromoly steel frame and suspension corrected fork; double-butted main triangle and 44mm headtube
  • Featuring Surly Dirt Wizard 29 x 3.0" tire spec
  • Clearance for 26 x 5.25" tires
  • 190/197mm rear spacing
  • Internal dropper seatpost routing


  • Frameset
Frame Surly 4130 Chromoly steel.
Fork Surly Wednesday, Tapered straight blade 4130 Chromoly.
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



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


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


Steerer Tube

Ø28.6mm (1-1/8")

Crown Race

Ø30mm (1-1/8")

Stock Headset Upper (S.H.I.S.)


Stock Headset Lower (S.H.I.S.)


Seat Collar




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


Fender Mounts Fork


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) 


Big Dummy Fat Geometry
Reach 408 432 448
Stack 578 597 625
Head Tube Angle 69.0° 69.0° 69.0°
Head Tube Length 100 120 150
Seat Tube Length 356 432 508
BB Drop 55 55 55
Wheelbase 1532 1563 1590
Chainstay Length 875 875 875
Top Tube Length, Actual 584 598 617.3
Top Tube Length, Effective 590 620 645
Seat Tube Angle 72.5° 72.5° 72.5°
Standover Height 746 792 841
Stem Length 60 70 80
Stem Angle
Handlebar Width 750 800 800
Crank Length 170 175 175
Fork Length 468 468 468
Fork Rake 47 47 47

NOTE: The Big Fat Dummy is only available in three sizes, which is a departure from our normal way. Here’s the thing, its sizing and fit is a little different than other bikes. By using shorter seat tubes with a longer seatpost, two people of different heights can ride the same size frame. We found it works pretty well.



We offer Free Shipping on all orders in the Continental US.

Orders typically ship within 1-2 business days.  

Orders ship from our stores in San Diego, California or from our suppliers located throughout the continental US.  Our network of warehouses allows us to deliver your orders faster so Uptown customers have access to a larger variety and better stock 

Shipping method and ship-times depend on ship-to address and size & dimensions of shipment. Our goal is to get your order to you quickly (typically 1-3 day shipping). Expedited shipping is also available.

We'll send your Order Tracking once your shipment is on its way.  We will also contact you once we hear your package has arrived to make sure it's been received and to offer our assistance.  For questions, changes or inquires on shipments please contact us.

Free Returns Button

We also offer Free Returns on most products (Click above to create your free pre-paid return label)

Accessories and Parts
We offer Free Returns for all accessories & parts returned within 30 days of purchase. That is a no-questions-asked full refund for items that unused/unworn & in original packaging. 

Accessory exceptions: Special orders and closeout deal purchases are final. Shoes may not have had cleats mounted nor show scuff marks. Helmets, shorts, jerseys, socks, gloves or other clothing may not have been worn. 

You may return a bicycle for the full purchase price within 14 days of purchase if the bicycle is in showroom condition as determined by us. When a bicycle was purchased as a special order or a closeout deal, the sale is final unless there was a problem with the order caused by Uptown Bicycles. Customer is responsible for return shipping on Bicycle orders unless there was a problem with the order caused by Uptown Bicycles

Bicycle Warranties
New bicycles typically come with manufacturer warranties. We will help you understand the warranty and coordinate any claims, but in the end, it is your responsibility to understand the warranty. Keep in mind, we hope that your bike experiences wear and tear, racing and maybe abuse, but hopefully not accidents. Warranties don't cover the result of those events.

Labor charges are not refundable. Unless, of course, there is a problem with the work performed, in which case, please contact us and we will immediately correct it.

If you have any questions about the above, let us know...we want you to buy with confidence.

The policies below applies to all in store purchase or online orders. If you are purchasing online and are unsure about a purchase, please give us a call...we can help a lot in your decision. (619)795-7222

Free Curbside Pickup

We offer Curbside Pickup / In-Store Pickup for all orders. 

Please select the the store location and the date you would like to pickup your order.  For Curbside Pickup, select In-Store Pickup at checkout.  You will receive details on how to pickup your order.  We have a dedicated loading/unloading zone directly in-front of each location.  Same-day curbside / in-store pickup is available on a case-by-case basis, as we may need a little time to put your order together. 

If selecting a bike for in-store purchase; availability for pickup reflects an estimate of when the bike will be ready.  Please note that this is an estimate, if you would like to pick an item up before the website shows it is available please contact us for special requests.  When we receive an in-store pickup order we will contact you by your preferred method entered at checkout to confirm details.

Why are some items available for In-Store (or Curbside) pickup only? 

Due to our brand relationships we are able to sell some products in-store only.  These products are not available to be ordered to be shipped to a customer's address.  We believe in the importance of proper assembly and maintenance of your bicycle, and respect our partnership with our brands as a dealer / retailer. If you have any questions please contact us.

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