Your basic hubs. Sorta like Chuck Taylor high tops for your bike. All are forged aluminum, high flange, and spin on high load, well sealed, adjustable cartridge bearings over solid or QR axles (9x1mm front, 10x1mm rear). It's easy to find replacements should the need arise. Fronts are spaced 100mm to fit most forks. Fixed-gear rears are spaced 120mm and are ISO threaded on both sides for fixed gear cogs (1.37"x24tpi) and lockrings (1.29"x24tpi LH). 135mm-spaced rears are available as dual freewheel, with threading on both sides for single speed freewheels (1.37"x24tpi), and as fixed/free, with freewheel threading on one side and fixed-gear/lockring threading on the other. We now offer this fixed/free hub in a 120mm-spaced version, as well. Black fronts and MTN rears are available with hollow axles. Drilled for 32 or 36 spokes and they're laser etched with the Surly logo. Color:Black or Silver Building some wheels and need our hub dimensions? Click here View a complete list of all our hubs here