You've approached the climb at Gates of Hell dozens of times. You've studied every possible line. You've eaten raw eggs. You've played the themes from several action hero movies during your attack. Nothing works the climb shuts you down every time and you wind up pushing to the top with your virtual tail between your very real, very worn out legs. Forget about testosterone shots maybe the answer is just an adjustment to your drivetrain. Meet the Wolf Tooth Components Giant Cog For Shimano. So, how giant is GIANT 40 or 42. That's not a typo 40 or 42 your choice teeth on your cassette. You could climb a tree with this thing. These days, most drivetrains have gone to a single or double up front and a larger cassette. This seems to be a winning combination for most folks, but there are those whose local terrain needs a bit more torque to conquer. Bear in mind the Wolf Tooth Giant Cog For Shimano only works with Shimano 10spd XT or XTR cassettes. The shift points are properly timed to the tooth locations on the 36T Shimano cogs. Also, use of this cog requires the removal of the 15T or 17T cog and spacer from your cassette. You will probably also need a longer chain.