The design comes about as a solution to the well documented creaking issues associated with oversized press-fit systems. While these issues are near always the result of poor tolerances, the T47 standard promises to fix the creaking issue without sacrificing the benefits of an oversized interface.

More recently, Cannondale announced a variant of BB30 called BB30A. This uses a shell that’s 5mm wider than the original but it’s an asymmetrical layout that only adds those extra millimetres on the non-driveside. According to Cannondale, this allows for wider bearing spacing and better spindle support (which should improve bearing longevity).Eyebrox wrote:It's the usual range of Shimano hierarchy options. The more you pay the better the quality. More recently, bearings have shown up that allow a 30mm spindle to be used. The dimensional restriction mean the bearings are generally quite small, as the system was designed around 24mm spindles. This can lead to reduced bearing lifetimes. Other notes Matches the wide bearing spacing of a BSA external BB with a large 30mm spindle BB392EVO

Pros: Vast crankset compatibility, open standard, threaded design easy to service and prevent from creaking, same dimensions as PF30Cons: Can’t use cup-mounted chain guides; shell is wider but still small in diameter; requires a separate bearing puller and press for service, bearing bores can wear out and loose tolerances Note: crankset for mounting on externally screwed in bearings, with a hollow axle 24 mm in diameter, is compatible whichever manufacturer produces it. So: Race Face X-type, FSA MegaEXO, Truvativ/SRAM Giga X Pipe (GXP), Campagnolo Ultra Torque – they are all compatible with Shimano Hollowtech II standard, so only Hollowtech II will be named in tables and remainder of the post.