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The GC 49 is the latest addition to the legendary GC line and it's the biggest yet. The GC 49 cassette extender cog allows you to modify your 11-speed 11-42T cassette from Shimano to create an ultra-wide range 11T-49T cassette. This is a wider range than a SRAM 10-42 cassette! To achieve the best shifting of any cassette expander cog, the GCs are optimized for Shimano or SRAM / SunRace cassettes so we have two different 49T cogs available. Includes 18T cassette cog for optimal gearing in the smaller cogs.

You might ask why 49t rather than 50t, and the answer is simple? It allowed us to nearly double the number of shift gates from 4 on a 50t to 7 on a you get much faster shifting. With cogs this big, this is critical as you can be waiting nearly a half revolution of the crankset before you will see a shift with only 4 shift gates. The 49t is only 2% different than a 50t, which is so small it will not be noticed.



  • Wolfcage is compatible ONLY with Shimano 11-speed rear derailleurs.  See the list below. Be sure to select the right cage length. Here are the pulley center to center distances for each cage type so you can be sure to order the right one (GS is the “medium cage” and SGS is “long cage” length):
    • XTR 9GS - 84mm (same cage as M8050 XT Di2).
    • XT 8GS - 88mm
    • XT 8SGS - 107mm
    • XTR Di2 M9050 GS - Not supported
    • XT Di2 M8050 GS - 84mm - use the XTR 9GS
  • Compatible only with Shimano 11-speed 11-42 and 11-46 cassettes (we have a SRAM cassette version also).
  • Compatible with all 11-speed chains
    • Note that you likely need a longer chain than you currently have your bike. Chain length is critical with the 49T and must be set according to the instructions on the GC tech page.
    • Chain wear should be less than .5 when installing a new GC or chainring.
  • Caution: always check full suspension travel with the chain on the GC 49. Bleed air from rear shock and fully compress the rear suspension to check. Derailleur cage must not bottom out in forward rotation.
    • This is a kit including the WolfCage, GC49 and 18t cog. Remove the 17t and 19t cogs and replace them with the 18t.
    • 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.


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    Tech Specs

    Weight: GC49 • 110g  | 18t cog • 22g  |  WolfCage • 22g
    Material: GC • 7075-T6 aluminum  WolfCage •  6061-T6 aluminum 
    Made in the USA

    Patent and trademark information