SRAM XX1 XG 1199 Cassette

At this point, you've likely made the leap, to swipe SRAM's marketing parlance. Whether you modified a 10 speed cassette with a One Up style expansion cog, or adopted early and wore out your first cassette, the SRAM XX1 XG 1199 Cassette is the pinnacle of one by technology. By trading freehub bodies for drivers, SRAM was able to put a tiny, 10 tooth cog on the end to balance out the monster, 42 tooth cog on the low end. This ensures that the balance of granny grinding to flat out flying is maintained.