My commuter is a 1x9, road bike 1x10, city bike Nexus 8 spd - seems like bike geometry, fit, tires, riding position, bike weight, tires, drive train set up and cleanliness, etc., effect speed more than the supposed 2-3 % loss due to IGH. My road bike is the fastest; the fit is optimized for speed, wheels & bearings smooth, aero wheels and tires - so I would anticipate it being faster than the city bike.