42T GC cog for Shimano
All Shimano GCs are still back-ordered but we are catching up fast and expect to ship all open orders by March 18th.
The GC42 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 GC42 cassette cog is the coolest cog around. This cog is made with the precision and finish our customers have come to expect from WTC, and this enables quite possibly the best feeling shift in the cassette.
Be sure to check out the GC tech page for more details
This cassette sprocket is for use only 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 cog & spacer from your cassette.
Note on “B-screw”: We will no longer be shipping a longer screw with each GC. We have found it is almost never needed with SRAM derailleurs and only needed for about 50% of Shimano derailleurs. We have added it as a separate item in our accessories category. If you think you might need the longer screw, order one separately or just go to your local hardware store and pick up an M4 x 25 socked head cap screw.
You may need a longer chain that what is presently on your bike. Make sure that when shifted to the 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 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 we do not recommend using the GC if you have one of these. The GC does work very well with the newer SRAM rear derailleurs however.