GXP/Long Spindle BB30 Chain Mounts to any GXP Crank and fits a Boost 148 Chain has been proven to improve traction and reduce leg fatigue. Ideal for 1 system 9/10/11 and single speed 52mm bosst 148 chain specification 11% ovality 7075 aluminium construction * If used in a 1x9 transmission a 10 sp chain must be used.