Shimano dura ace r9150 di2 11 speed groupseteach component of shimanos dura ace r9150 groupset has been re engineered to ensure maximum stiffness performance and efficiency at the lightest possible weight synchro shiftfor the first time in a dura ace groupset shimanos innovative synchro shift is now as a programmable di2 option synchro shift creates an intuitive experience with synchronised front and rear shifting which can be custom programmed with full and semi synchro shift availab