Ridden and Reviewed- Wolf Tooth Components 40t Shimano GC Cog

wolf tooth

As the old saying goes there is more than one way to skin a cat.

Wolf Tooth Components is a small company ouf of Minnesota that has made its name with aftermarket XX1 style chainrings and conversion cogs.  They design and manufacture in-state and support a surprising number of World Cup XC racers who run a 1x Shimano drivetrain with drop stop chainrings and their GC conversion cogs.

The GC cog is basically a way to get the range of the vaunted SRAM 11 speed cassette with an existing 10 speed drivetrain.  It’s an adapted solution, so without adding an extra click you have to remove one of the smaller individual cassette cogs to make it all run.  I opted for the 40t rather than the 42t because it offered smaller gaps between gears and required less B screw tension.  All of that should mean slightly crisper shifts.  To make room for the 40t on my Shimano XT test cassette I had to remove the 15 or the 17, and honestly neither option was appealing as the jump between cogs was huge.  It shifted fine with either removed, but the difference in gear inches under power was hard to handle.

After fiddling around with a few different configurations I ordered Wolf Tooth’s 16t cog which essentially means removing the 15 and 17 so that the 16 sits in the middle.  The difference in spacing is pretty consistent through the range and following instructions for Shimano or SRAM means you can align the shift gates so they work properly.

While the 16t cog works well with either manufacturer the GC cog is specific to SRAM or Shimano and is not compatible with every cassette available (Neither Shimano SLX nor the SRAM 1080 will work) but options from the XT/X9 wheelhouse are both available.  Following these directions Wolf Tooth promises smooth, consistent shifting and after riding this setup for most of the summer I have to say that I fully agree.  If you didn’t know that this setup was installed you would never know from shifting quality or gear spacing that it was anything other than a normal cassette- and I have to say that’s a really good thing.

This ringing endorsement does not however cover all conversion setups.  I also tried a rival company’s conversion and had a miserable experience pushing my bike up usually rideable inclines because the chain would not stay in the lowest gear without jumping every pedal stroke.  Although it shifted consistently in the work stand it did not handle the torque loads of slow, technical climbs out on the trail- and that’s really the only thing it is designed to do.  No adjustment to the rear derailleur could be made to accomodate the new cog, nor did changing the chain have any impact, but the reinstalled Wolf Tooth worked flawlessly without any further adjustment.

Whether this is worth it for you depends on your application.  It works well for fatbikes, trail bikes, and even XC race rigs as long as you can handle your preferred terrain with a 30 or 32t chainring.   The additional chain required to handle the huge 40t means that you can only run this with a single front chainring and not 2x or 3x setups.  Most riders are looking to go to this to remove the additional chainrings so it should be a non-issue, but it’s worth mentioning.

For more information visit wolftoothcycling.com.

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  1. says: Christopher

    From WOlf Tooth FAQ:
    Q: Can I use the GC with my 2X front gearing?

    A: Yes, it works great with both 1X and 2X. It will probably even work with 3X if you can find a chain long enough. We recommend a minimum front chainring size of 26T to avoid excessive torque on the freehub (i.e. don’t use a 22T granny gear or you might damage your hub).

  2. says: Michael Chiu

    i did remove 17 after installing the wolftooth 42t. so what happened next was shifting from 15t to 19t is a problem. the chain would not climb to 19t. adjusting the tension would solve the problem. but the new problem is when you are on the larger cog, the chain refuse to step down to the lower cog. and so i bought the 16t. the same problem. im using a 2×10 xt. i really need my 42t because i love climbing in stiffer slopes.

    1. says: Matt

      Assuming you’ve got new and freshly lubed cables, a new chain, and an appropriate rear derailleur as specified on the Wolf Tooth tech page I’d suggest checking with Wolf Tooth. Minor differences in chain line, chain length, and derailleur cage length are all magnified with the lower gear range, and my personal recommendation would be to only run this with a single ring up front. That was Wolf Tooth’s original recommendation as well, and to make a double run I’d presume you’d need a long cage rear derailleur to be able to take up the slack in the small/small combination.

  3. says: Michael Chiu

    hi matt, thanks for the reply. i have a long cage rear derailleur and my cable are not lubed because the mechanic did not lube it when he changed my cable. 16 to 19t transition is my only problem. the rest runs smoothly. actually there are times that 16 to 19t transition works but intermittently. maybe i need to lube my cable. merry christmas to you man.

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