T47 vs BSA
Quick verdict
T47 (threaded, 47mm shell, M47 × 1mm thread) and BSA (threaded, 34.8mm shell, 1.37" × 24 TPI thread) are different frame standards and are not interchangeable. Buy the bottom bracket that matches your frame, then match its spindle to your crank.
| T47 | BSA | |
|---|---|---|
| Full name | T47 Threaded | BSA / English Threaded |
| Fitment | threaded | threaded |
| Shell | 47mm shell, M47 × 1mm thread | 34.8mm shell, 1.37" × 24 TPI thread |
| Also known as | T47 internal, T47 external, T47a, T47i | BSC, English, ISO, 1.37" x 24 TPI |
| Frames listed | 45 | 234 |
| Bottom brackets listed | 35 | 68 |
| Guide | T47 compatibility → | BSA compatibility → |
Frequently Asked Questions
Can I fit a BSA bottom bracket in a T47 frame?
No. T47 (47mm shell, M47 × 1mm thread) and BSA (34.8mm shell, 1.37" × 24 TPI thread) are different frame interfaces, so a BSA bottom bracket will not fit a T47 frame. You need a bottom bracket built for your frame's standard.
What is the difference between T47 and BSA?
T47 is threaded (47mm shell, M47 × 1mm thread); BSA is threaded (34.8mm shell, 1.37" × 24 TPI thread). Both are threaded standards, so they differ mainly in shell dimensions and which frames use them.
Is T47 better than BSA?
Both are threaded and creak-free. BSA uses a narrow 34.8mm thread suited to 24mm cranks; T47 uses a wide 47mm thread that also swallows a full 30mm spindle, so it is more versatile on modern frames. For a 24mm Shimano crank on a road bike, BSA is simpler; for large-bore frames or 30mm cranks, T47 is the threaded answer to press-fit creak.
Check your exact combination
Frame standard, bottom bracket and crank spindle all have to line up. Drop your parts into a build and our engine verifies the whole bottom-bracket chain for you.
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