The Praxis Works Shimano Hollowtech II bottom bracket converter is designed to be a proper bottom bracket BB for installing Shimano Hollowtech II cranks in either BB30, PF30, or Specialized s OSBB road frames. Our patent pending design keeps the cartridge bearings outboard of the frame right on Shimano spec for greater rigidity and free of frame/c-clip tolerance issues that other conversion bb systems deal with.Patent Pending Outboard Bearing Design Collet style non-drive cup expansion for wiggle-free pressNon-Drive O-Ring compensates for frame width discrepanciesFor BB30, PF30, and Specialized Road OSBB frames onlyFor Shimano Hollowtech II cranksShimano 24mm MTB 73mm BB30/PF30Simply press in the longer non-drive-cup, then the shorter drive cup threads into it. As the drive cup threads in, our trademark Collet system expands to a precise limit evenly dispersing pressure for a super tight fit. With both cups connected and our collet set exactly to spec, there is no chance the bearings