Shell BSA vs Shell T47ext: specs compared
Updated 05 September 2026.
4
specs differ
Shell BSA and Shell T47ext differ on 4 specs: shell inside diameter, shell width, thread, crank spindles it hosts.
| Spec | Shell BSA | Shell T47ext |
|---|---|---|
| Type | threaded | threaded |
| Shell inside diameter | 1.37 in (about 34.8 mm) threaded bore | about 46 mm bore, cut with an M47 x 1.0 thread |
| Shell width | 68 mm (road), 73 mm (MTB), 83 mm and 100 mm (fat / DH) | 68 mm and 73 mm |
| Thread | 1.37 in x 24 TPI, drive-side cup left-hand (reverse) thread, non-drive right-hand | M47 x 1.0 (47 mm outside thread diameter, 1.0 mm pitch), drive-side left-hand |
| Crank spindles it hosts | 24 mm (Shimano Hollowtech II), 24/22 mm (SRAM GXP) and 28.99 mm (SRAM DUB) via the matching threaded BB | 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 |
Questions and answers
How do Shell BSA and Shell T47ext compare?
Shell BSA and Shell T47ext differ on 4 specs: shell inside diameter, shell width, thread, crank spindles it hosts.