Remember "granny gear?" Like the fanny pack, it was useful, although the nickname had its negative implications. Also like fanny packs, granny gears are still available, although the plummeting demand dictates that their days are probably numbered. This poses a problem for mountain bikers whose nearby favorites fall into the category of "barely climbable." If you've ever wondered: What's the absolute maximum number of teeth that my rear cassette can hold, shift into, and slow-pedal up that nasty 45-degree climb a mile from my front porch," the Wolf Tooth Components Giant Cog For SRAM has the answer. 40 or 42. That's not a typo -- 40 or 42 (your choice) friggin' teeth. You could climb a tree with this thing. Bear in mind -- the Wolf Tooth Giant Cog For SRAM only works with PG 1030, 1050, and 1070 11-36 and 12-36 cassettes or X0 11-36t (XG-1080) cassettes. 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.