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. Praxis Shim BB30/PF30 68mm Bottom Bracket Features 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.