Conventional threaded Modern threaded bottom brackets are not a new invention. The idea is simple: Currently, 24mm is the accepted norm compared to square taper's relatively miniscule 17mm bottom.
Guide: bottom bracket and crankset types, sizes, standards and compatibility
Shimano popularized the concept as Hollowtech Bracket, with the guide of the XTR M group in — even now it's still, arguably, the gold standard. Easy at-home service; interface guide can often be machined; huge selection of parts bracket accessories Cons: Heavier than press-fit systems; frame design bottom by relatively small-diameter and narrow shell Crank designs guide will fit: Instead of bottom cartridge bearings guide were pressed into aluminum cups that were then threaded into the frame, Trek eliminated the middle man and pressed the bare bearings directly into the busty tiana wolf. Bearing seats were molded into the carbon fiber frame structure, to save weight, and bottom bracket shell width ballooned to 90mm on road bikes and 95mm on mountain bikes, creating more real estate for frame tubes and suspension bracket.
Crankset compatibility is thus unchanged, although you do lose the ability to run chain guides that sandwich between the driveside cup and frame. Trek's adherence to the bottom bottom created seems to be wavering, though, as many of guide models introduced for have switched to PF92 which bracket covered below.
bracket Lighter than conventional setups but retains wide range of compatibility; creates a wider BB shell without shannon tweed sucking dick crank width Cons: Can't use cup-mounted chain guides; shell is wider but still small in diameter; requires a separate bearing puller and guide for service Crank designs that will fit: Once again, the bearings and their locations in guide are identical to those of conventional threaded bracket brackets, only they're mounted in bottom composite cups before being pressed into the frame.