Product Overview
AndyMark has been selling hubs specifically designed for competition robots since 2006. Over the past 13 years, we've expanded upon this line, making subtle changes along the way. We took everything we've learned, and we designed a brand new line of high strength, high quality hubs for competition robots. These new designs take the best features cherry-picked from our different hub designs of the past, and combines them all into one unified design. 
Each hub now has a "flower" pattern that fits and keys into our 42T 5mm HTD Pulley, which means you are no longer constrained to our legacy 500EX Hex Hub for compatibility with this pulley. Every hub still maintains a closed-profile hole for maximum strength. Every shaft hub has been designed with bearing bosses on both sides that have been sized appropriately for the mating bearings that would pair with the bore through the hub, which means you can run each hub right against a bearing with no need for extra spacers. All of these hubs are also made from 7075-T6 aluminum, which is much stronger than the previously used 6061-T6, 6005 and 6105 alloys from our older designs. Where possible, the shoulder on shaft hubs was reduced to 7/8" in diameter for an easier fit with our molded plastic wheels, while still maintaining a precise 1.125" diameter boss for locating in wheels, sprockets, gears and more. 
Specifications
Bolt Pattern: 0.201" diameter holes, evenly spaced on a 1.875" diameter bolt circle
Bore: 1/2 in. Hex, ⠀3/8 in. Hex, ⠀8 mm Key, ⠀3/8 in. Key, ⠀5/8 in. Key, ⠀Bearing
Material: 7075-T6 Aluminum
Outside Diameter: 2.31 in.
Weight: 0.092 - 0.114 lbs
Width: 1 in.