Shimano dura ace 9000 double 11sp chainsetthrough its unique and distinctive four arm design which has precisely where the maximum intensity where the greatest loads occur and by the hollowtech ii technology uses the fc 9000 crankset a new standard in terms of stiffness and low weight optimum transmission is guaranteed please note bottom bracket is not included features optimum power transfer lighter weight maintains efficiency new chain guide design to reduce chain drop 4 arm construct