Compatibility These direct mount chainrings will your existing chainring and spider, which is attached via 3 bolts on the back side of the spider near the spindle. You will use these same 3 bolts to attach the Wolf Tooth SDM chainring. Note that the SRAM 12spd Red and Force AXS use a different 8 bolt mounting interface that is not compatible with these chainrings. Also compatible with Cane Creek eeWing cranksets. There are 3 offsets: Standard Road/CX/Gravel: 6mm offset for cyclocross and road crank applications with 47mm chainline Standard MTB: 6mm offset for non-Boost mountain bikes, GXP and long spindle BB30 cranks for 49mm chainline Boost: 3mm offset for 52mm chainline BB30: 0mm offset for BB30 short spindle cranks for 49mm chainline Fat Bikes: If you are planning to use this on an X9 or XX1 fat bike crankset with a 190/197 rear hub spacing use the 0 offset ring. If your fat bike has a 170/177 rear hub spacing, use the Standard 6mm offset Praxis Works Road/CX cranks use the 6mm offset. Praxis Works mountain cranks use the 3mm offset for their DM-A and 0mm offset for their DM-B chainrings. If you have a BB30 crankset (30mm diameter aluminum spindle) the measurement pictured below will help you determine whether it is a long or short spindle.