The introduction of 11-36T cassetes a few years ago changed mountain biking forever. The larger gear range made 1x drivetrains more practical, but some found that it still wasn't a wide enough gear range. This add-on cog replaces one of the middle cogs in your 10-speed cassette cluster, giving you an extra-low 40T or 42T granny gear without requiring you to upgrade your entire drivetrain!
Wolf Tooth's GC cassette cog is so big that when machining the first batch, the machinist thought he made a mistake! If being big is cool then the GC cassette cog is the coolest cog around. This cog is made with the premium precision and finish one can expect from WTC, and this enables quite possibly the best feeling shift in the cassette. This cassette sprocket is only for use with Shimano brand 10spd XT & XTR cassettes. It is NOT compatible with any other brand or model of cassette. The shift points are properly timed to the tooth locations on the 36t Shimano cogs for optimal shifting performance. Use of this cassette sprocket requires removal of the 17T or 15T cog & spacer from your cassette.
Note on “B-screw”: A longer screw is almost never needed with SRAM derailleurs and only needed for about 50% of Shimano derailleurs. If you think you might need the longer B-screw, order one separately or just go to your local hardware store and pick up an M4 x 25 socket head cap screw.
You may need a longer chain than what is presently on your bike. Make sure that when shifted to the 40/42T cog, there is still some amount of forward travel possible with the rear derailleur cage. This is especially important on bikes with rear suspension. We have tested with Shimano, KMC & SRAM chains €“ all function well.
Compatible only with the following Shimano 10spd cassettes:
XT 11-36t (CS-M771)
XTR 11-36t (M980)
Not compatible with SLX 11-36 cassettes because the 17t cog cannot be removed.
Note: the GC 42 is not compatible with 2011 or older SRAM rear derailleurs due to the location of the upper jockey wheel. It is difficult or impossible to get satisfactory shifting with the 2011 or older SRAM rear derailleurs so it is not recommended to use the GC if you have one of these. The GC works great with the newer SRAM rear derailleurs however.
Check out the GC tech page @ Wolf Tooth for more details.
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