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e*thirteen components Extended Range Cog

up to 15% Off
sale $59.46 Original price:$69.95

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  • Black, 42t for SRAM
    sale $59.46

Extended Range Cog

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.

  • Extend your one-by drivetrain's gearing to a knee-friendly 40 or 42t cog
  • Item #ETR000G

Cog Sizes
40 t, 42 t
Cog Material
EXA+ aluminum
Claimed Weight
[40t] 70 g, [42t] 76 g
Recommended Use
mountain biking
Manufacturer Warranty
2 years

Tech Specs

What do you think about this product?


>Rating: 4

1x in a jiffy

I've used it once or twice and have initial impressions

Great tool for converting your older 2x10 to a 1x10. It is a simple installation process, just make sure you have a cassette that the 15 or 17 tooth cog can be removed or you will struggle to install. Standard e-thirteen quality, and it looks great too.

>Rating: 5

Leg Saver!!!!

I've put it through the wringer

Make your old 2x10 into a 1x10. I made the switch without the extended range set up... it was not worth it. When I put it on the extended range gear it made a huge difference and my legs thanked me for it. Has no issues if adjusted correctly. Having a clutched rear derailleur also helps.

>Rating: 5

Greatest upgrade

Having run 1x10 and 1x11, I almost prefer a 1x10 Shimano upgrade over the 1x11 for a few simple reasons. Cost is significantly less if you're already running a 10 speed rear derailleur and shifter (XT or XTR is best here). 11 speed will require a new shifter, derailleur, cassette and potentially a hub driver. Depending on the riding you do, it is a bit quicker to go from top to bottom in 10 gears than 11 with the same overall ratio as the XTR 11sp. You only miss one gear in the mid range in comparison. Shifting is still smooth, installation is pretty simple and set up easy with the included B-Screw to give your derailleur clearance. Other upgrades to make this run even better would be a Radr cage from OneUp and a race face narrow wide chain ring for your crank. Overall, awesome product and the best bang for the buck when upgrading your bike.


I'm currently running full Shimano 9spd Xt setup and looking at swapping into a 1x9 with a RaceFace Narrow Wide chainring. Is it an option for me to add this cog to a 9spd cassette is a swap out another cog?