SHIMANO E-BIKE MOTOR DM CHAINRING - DROP-STOP BWolf Tooth Direct Mount Chainrings for Shimano E Bike Motors have a 55mm chainline and are compatible with all Boost and Super Boost bikes that use the Shimano EP8, E8000, and E7000 e bike motor splines. Direct Mount Chainrings for Shimano E Bike Motors are machined with 7075 T6 aluminum at Wolf Tooth in Minnesota, USA. The Drop Stop B tooth profile is compatible with almost all 9 , 10 , 11 , and 12 speed chains the only exception is Shimano