You asked for it, we made it -- the Wolf Tooth GC is now available in a slightly smaller size! Most of the low gearing from its big brother with improved shifting in the smaller cassette cogs.
Be sure to check out the GC tech page for more details
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”: We have found a longer screw 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 socket head cap screw.
You may need a longer chain than what is presently on your bike. Make sure that when shifted to the 40T 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: unlike the 42T, the GC 40T will usually work with 2011 or older SRAM rear derailleurs. We cannot guarantee it on all bikes however.