T47 external (T47-68 / T47-73) bottom bracket shell (M47 x 1.0, 68/73 mm)
What a T47 external (T47-68 / T47-73) shell measures, which crank spindles it hosts, and the bottom bracket to buy.
Published dimensions
| Type | threaded |
|---|---|
| Shell inside diameter | about 46 mm bore, cut with an M47 x 1.0 thread |
| Shell width | 68 mm and 73 mm |
| Thread | M47 x 1.0 (47 mm outside thread diameter, 1.0 mm pitch), drive-side left-hand |
| Crank spindles it hosts | 24 mm (Shimano), 24/22 mm (GXP) and 28.99 mm (DUB) via the matching T47 BB; the 46 mm bore clears a 30 mm spindle |
SHELL 68 mm and 73 mm
SPINDLE 24 mm (Shimano), 24/22 mm (GXP) and 28.99 mm (DUB) via the matching T47 BB; the 46 mm bore clears a 30 mm spindle
SPINDLE 24 mm (Shimano), 24/22 mm (GXP) and 28.99 mm (DUB) via the matching T47 BB; the 46 mm bore clears a 30 mm spindle
Used on: gravel and road frames wanting a threaded BB with the larger 46 mm bore.
On a 68 or 73 mm T47 shell the bearings sit outboard of the frame, like an English BB, so it is called external. It takes the same M47 x 1.0 thread as internal T47 but a different length BB, so confirm the shell width before buying.
Fit a crank to this shell
Shimano Hollowtech II (24 mm) in a T47 external (T47-68 / T47-73) shelldrops inT47 internal (T47-85.5 / T47-86 / T47-92)related shell (M47 x 1.0, 85.5-92 mm)
SOURCES: White Industries, External T47 Bottom Bracket · Escape Collective, Threaded #12: the woes of T47 bottom brackets