The shimano ultegra bb r60 6800 bottom bracket is hollowtech ii integrated bottom bracket uses a wider bearing placement and larger axle diameter for increased stiffness and efficiency the hollowtech ii integrated bottom bracket seal design has minimal bearing interface ensuring smooth rolling and increased durability for this bottom bracket uses tlfc37 or tlfc25 in conjunction with tlfc36 adaptor tool for installation and removal available in italian or british thread shimano ultegra bb r60