e-thirteen have just announced a new cog which should extend the gear range of 10 speed Shimano and SRAM cassettes. It’s especially for guys who are OK with ten speed and don’t want to spend tons of money to go to 11 speed and get a 42 tooth cog.

The 42t cog is compatible with 36t cassettes, while 40t is compatible with 34t cassettes. The 40t cog is only available for Shimano as SRAM is not offering a 34t cassette. The EX cogs are machined and ramped specific to either Shimano or SRAM cassettes. They come with a longer steel replacement B-limit screw for your derailleurs because your current one won’t be long enough to get the best shifting up to the new cog.


To check compatibility with your current cassette please check the compatibility chart on the e-thirteen website. e-thirteen do not recommended using the 40t extended range cog with a 36t max cassette because the shift timing is not optimized for this use and will probably offer sub-par shifting. The 42t extended range cog will not work with 34t max cassettes.

Extended Range Cog Compatibility_B

The EX cogs are available in Black, Blue or Red

MSRP: $69.95 USD

Shipping to stores starting on May 15

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