Freehub Kit ZR1 XD-R 12 Spd.Replacement freehub for Zipp ZR1 Hubs Lets start with bearing preload, a key factor in hub performance and durability. Zipps Cognition, ZR1, and ZM2 hubsets feature the automatic bearing preload for longer bearing life and easier serviceability. Previous versions of Zipp hubs featured a set screw to adjust preload. While this system allowed riders to dial in their preferred preload, the Schweinfurt team developed a more precise and straightforward