Surly Big Fat Dummy

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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


Frame Surly 4130 Chromoly steel.
Fork Surly Wednesday, Tapered straight blade 4130 Chromoly.
Seatpost Clamp 33.1mm (Surly stainless included)


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


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


Front Hub Novatec, 32h, Thru-Axle
Rear Hub Novatec, 32h, Thru-Axle
Rims WTB Scraper i40 ST TCS
Tires Surly Dirt Wizard 29x3 60tpi