The product that set the standard and still the best available! The GC line of cassette extender cogs allows you to modify your 10-speed cassette into a wide range cassette. To achieve the optimal shifting, the GCs are optimized for Shimano or SRAM cassette so always select the correct type for the cassette brand you have.

Compatibility

Compatible with SRAM 10-speed cassettes listed on the GC tech page
Compatible with all 10-speed chains

Note that you may need a longer chain that you currently have your bike
Chain stretch should be less than .5 when installing a new GC

Compatible with all 10 speed rear derailleurs except non-clutch type SRAM rear derailleurs model year 2012 and older

These older rear derailleurs do work with the GC40.

Can be run in 2x configuration with a long cage rear derailleur
Hub compatibility

These may fit tightly on some over-sized hub bodies such as Stan's No Tubes 3.30 and the Easton X4 hubs. With a little filing and some grease, they will go on.

These are specifically designed for use with SRAM cassettes. The clocking, or rotational orientation, between SRAM and Shimano cassettes are much different so optimal shifting cannot be achieved unless the design is optimized for each separately.

Related Products

Goatlink - improve the long term shifting when using a Shimano rear derailleur (HIGHLY recommended over the longer b-screw)
16t replacement cog - smooth out those cassette transitions
Longer b-screw - necessary with some SRAM GC42 and Shimano GC40 applications. Necessary on all Shimano GC42 applications if not using the Goatlink

Tech Specs

Weight: 86g
Material: 7075-T6 aluminum
Made in the USA

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