BSA vs T47: is modern threaded worth it?
BSA and T47 are both threaded (they screw into the frame and rarely creak), but they use different threads: BSA is 1.37″ × 24 TPI (narrow shell) and T47 is M47 × 1.0 (wide shell). They are not interchangeable. T47's advantage: its wide shell houses stout 30 mm spindles with a good bearing, which BSA can't.
If you have BSA and it works, there's nothing to fix: it's reliable and universal. T47 isn't an upgrade you buy; it's the frame's standard. The comparison matters when choosing a new bike or frame.
How they're alike and how they differ
Both share the upside of threaded: easy to service and rarely creak. The difference is size. BSA has a narrow shell, built for 24 mm spindles. T47 has a wide shell (like a PF30) but threaded, combining 30 mm spindle stiffness with the peace of mind of threads.
Comparison
Which suits you?
You don't pick between them part by part: your frame decides. If your frame is BSA, stick with BSA: reliable and cheap. If you're buying a high-end frame and can choose, T47 gives 30 mm stiffness without press-fit creak. Both accept Shimano 24 mm and SRAM DUB.
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Frequently asked questions
Is T47 better than BSA?
For wide shells and 30 mm spindles, T47 offers more stiffness. For reliability and low cost, BSA is still excellent. There's no absolute winner: it depends on the frame.
Can I convert my BSA frame to T47?
Not simply: they're different threads. The standard is set by the frame at the factory.
Do both accept SRAM DUB?
Yes, with the DUB cup matching each standard.