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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. 


  • Compatible with Shimano 10-speed cassettes listed on the GC tech page
  • Compatible with all 10-speed rear derailleurs and chains
    • Chain stretch should be less than .5 when installing a new GC


    You may need a longer chain that you currently have your bike

      • Can be run in 2x configuration with a long cage rear derailleur
      • Hub compatibility
        • These fit very tight on certain Stan’s No Tubes hubs like the 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 Shimano 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)
        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: 79g
        Material: 7075-T6 aluminum
        Made in the USA

          WARNING Handling this product will expose you to chemicals, including lead, known to the State of California to cause cancer and birth defects or other reproductive harm. Wash hands after handling. For further information go to​

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