Shimano m5100 deore 11 sp boost double chainsetready for the steep stuff, the fast stuff, as well as the fun stuff, this 11 speed mtb crankset gives you powerful acceleration and smooth shifting performance. It features a hard wearing forged alloy crank arm construction, which allows it to handle all the abuse that's associated with all day epics in the mountains. Shimano has also kitted out this model with a hollowtech ii integrated bottom bracket design for increased stiffness, efficiency and added durability.features crank arm material forged alloy use mtb speed 2x11 speed number of chainrings 2 chainrings included yes design 2 piece chainline 51.8mm chainring bcd for use with 148 mm o.l.d. Frames 4 arm or 5 arm 4 arm chainring size 36 26t is bb included hollowtech ii integrated bottom bracketpart numbers 170mm fcm5100bc66 175mm fcm5100be66technologies hollowtech ii hollowtech ii integrated bottom bracket design uses a wide bearing placement with a large axle diameter for increased stiffness, efficiency and added durability. Forged crank arms forged crank arms rigid whilst being incredibly strong and durable.a 2 year warranty is offered with all shimano products from chain reaction cycles 3 years on dura ace and xtr products.buy shimano components from chain reaction cycles, the world's largest online bike store.