The Shimano BB-RS501 bottom bracket features an enhanced seal construction to provide long-lasting performance and service life.For use with English thread bottom bracket framesDesigned for a perfect fit with Hollowtech II 24mm crank spindles Anodized aluminum cups are high strength and light weightItem SpecificationsBB Shell Width (mm)68BB/Frame InterfaceEnglishBottom Bracket Shell I.D.1.37Defined ColorSilverkeyword searchRS-500Spindle Interface TypeShimano Hollowtech IIWeight93