Ok...so you have BB30, PF30 or a Specialized OSBB frame, but you need to run a different crank   No worries. Our Praxis Works Conversion BB is just what you're looking for. Made to fit in either BB30 or PF30 frame.   Specification: The converter works with either BB30 or PF30. . To fit the converter to a BB30 frame, please remove the plastic sleeve (tube). . To fit the converter to a PF30 frame, please fit the converter with the plastic sleeve (tube).. 68mm for Shimano Road Cranks. 73mm for Shimano MTB Cranks. Designed for Shimano™ 24mm Hollowtech II cranks. . Frame Guide Praxis Bottom Bracket Converters are available for both 68 and 73mm shell sizes.