e*thirteen components Extended Range Cog Black, 42t for Shimano

Back before the age of derailleurs, dudes had to climb alpine passes on singlespeeds with a flippable rear wheel that had two cogs: big and bigger. Fast forward nearly a century, and e*thirteen components' Extended Range Cog bumps your one-by drivetrain's cassette range up to the granniest of granny gearings, effectively adding a chainring to the bottom end of your cogs. With a capacity of 40 or 42 teeth, the Extended Range Cog levels the grade to make sure you get to the top without crunching all the cartilage out of your knees.