Tubing 100% Surly 4130 CroMoly steel. Main triangle double-butted. TIG-welded
Rear dropouts Proprietary Surly 4130, 135mm spaced
Brake compatibility International Standard disc or cantilever rim-type
Braze-ons Removable cantilever bosses, dual water-bottle mounts, downtube shift cable routing, guides for hydraulic hose or solid housing, ICGS chainguide mount
Seatpost diameter 29.4mm
Seatpost clamp diameter 31.8mm (1-1/4″), Surly Constrictor included
Headset 1-1/8″ threadless
Front derailleur size 31.8mm (1-1/4″) bottom-pull
Bottom bracket shell 73mm wide, threaded English 1.37 x 24t
Tire clearance 26 x 2.7″
Chainring clearance 48t max
Fork Compatibility Geometry is designed around a 100mm 130mm suspension fork. Using shorter or longer forks will compromise intended ride characteristics, i.e. less BB clearance, faster or slower handling, etc. Most of you will choose a suspension fork, so we don’t include a fork with this frame, but we do make a rigid fork for the Instigator
Weight 18″ = 6.61 lbs. (3.0 kg)