Surly says... The Lowside is the bike that gets you across town for a quick rip on singletrack, then over to the bar for a night out. It should come as no surprise that singlespeeds run deep in our DNA and have since day one.
Let’s take a brief jaunt down the ‘ol memory lane, shall we? Way back in ’98, we launched the 1x1 Rat Ride. It was our first frame, and, for a lot of people, a first foray into the world of singlespeeds. After many years and many trips to our favorite bar, the Sunrise, we decided to discontinue it. The Lowside picks up right where the 1x1 left off.

We added in some fancy new modern features like a hole for a dropper post cable, our Gnot-Boost rear spacing, and thru-axles, but don’t let all that scare you. We didn’t leave you late-adopters behind. Lowside’s Gnot-Boost rear spacing is compatible with 142 x 12mm or 148 x 12mm thru-axle rear hubs as well as 135 x 10mm QR hubs (when using 10/12 Adapter Washers). That cross compatibility makes the Lowside a perfect parts-bin bike. If you have parts lying around, chances are they’ll work (unless you have rim brakes, those won’t work here).

Lowside also features a 110 x 15mm fork with a generous tire clearance of 27.5 x 2.8˝ or 26 x 3˝. We spec it with 26+ Dirt Wizards and a Sunrise Bar so you have no excuse to be boring.

Hop curbs, cut through alleys, and find some shortcuts. If you’re looking for some mischief on the way to the trail, you can find it on Lowside.

Specifications:

Frame Construction: 4130 Chromoly, Natch tubing, double-butted main triangle, TIG welded, ED coated
Fork Construction:4130 Chromoly, Natch tubing, double-butted tapered fork blades, TIG welded, ED coated
Rear Dropout Configuration: Horizontal slotted with optional vertical dumpout
Rear Hub Spacing: "Gnot-Boost" 145mm, 12 x 142mm or 12 x 148mm (Surly axle included), 10 x 135mm with Surly 10/12 Adapter Washers (not included)
Front Hub Spacing: 15 x 110mm (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), 26mm offset adapter (not included) for 142 or 135mm rear hub spacing, 29mm offset adapter (not included) for 148mm rear hub spacing
Max Chainring (CL) [3]: 1x (Mtn):  33T, 1x (Boost):  36T
Bottom Bracket: 73mm threaded (1.37" x 24TPI)
Tire Clearance Frame [1]/[2]: 26 x 3.0", 27.5 x 2.8"
Tire Clearance Fork [1]: 26 x 3.0", 27.5 x 2.8"
Rigid Fork Spec: 420 x 47mm
Max Suspension Fork Length [4]: 490 x 47mm (26 100mm)
Bottle Mounts Frame: 1 Standard
Bottle Mounts Fork: N/A
Rack Mounts Frame: N/A
Rack Mounts Fork: N/A
Fender Mounts Frame: N/A
Fender Mounts Fork: N/A
Other Features: 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 the 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)