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Threaded vs pressfit bottom brackets
A threaded shell holds its bearings with cut threads; a pressfit shell holds them with an interference fit, and that single difference drives almost every practical trade-off.
How each interface holds the bearings
A threaded bottom bracket uses cups that screw into threads machined in the frame shell. On a BSA shell the drive-side is a left-hand (reverse) thread, so pedalling forces tend to tighten it rather than back it out. An Italian shell threads right-hand on both sides. T47 is also threaded, at 47mm with a 1mm pitch.
A pressfit bottom bracket has no threads. The bearings, or cups carrying the bearings, are pushed into a smooth bore with a press. BB86 and BB92 use cups pressed into a 41mm bore; BB30 presses the bearings straight into a 42mm bore; PF30 presses cups into a 46mm bore.
Why pressfit gets a reputation for creaking
Pressfit relies on a precise interference fit between two hard surfaces. If the frame bore or the bearing outer is even slightly off tolerance, or the shell is not perfectly round after painting, the parts can micro-move under load and creak. Carbon frames add the complication that the bore is moulded rather than machined.
Threaded interfaces are more forgiving because the threads and a torque spec pull the cups firmly against the shell faces. This is the main reason many riders and frame builders have moved back toward threaded standards such as T47, which keeps a large-diameter shell but adds threads.
Serviceability at home
Threaded cups fit and remove with a splined tool and a workshop bench; no press is needed. Pressfit removal and installation ideally use a proper press and drift set to keep everything square, and a botched install is a common source of damage on alloy and carbon shells alike.
For a home mechanic, threaded is the lower-stress option. Pressfit is not inherently bad; done to tolerance with the right tools it runs silently and can be lighter and stiffer, but it is less tolerant of shortcuts.
Which spindle sizes each supports
Shell diameter sets the largest spindle you can run. A 24mm Shimano spindle fits nearly everything with the right adapter. Larger 30mm and DUB 28.99mm spindles want the bigger bores of PF30, BB30 or T47. Fitting a narrow 24mm crank into a wide pressfit shell needs a reducer bottom bracket, which is where a lot of compatibility questions start.
| Interface | How it holds | Home fit | Creak risk |
|---|---|---|---|
| BSA threaded | Cups screw in | Splined tool | Low |
| T47 threaded | Cups screw in | Splined tool | Low |
| BB86/92 | Cups pressed | Press needed | Moderate |
| PF30 | Cups pressed | Press needed | Moderate |
| BB30 | Bearings pressed | Press needed | Higher |
Threaded and pressfit families at a glance
Threaded or pressfit, find the right BB
Open the BB compatibility toolMatch your shell to your crank spindle in a couple of clicks.Find bottom bracket bearing press tool on eBayaffiliateRelated
Sources: Park Tool bottom bracket reference ยท BikeGremlin