BSA vs Italian
Quick verdict
BSA (threaded, 34.8mm shell, 1.37" × 24 TPI thread) and Italian (threaded, 36mm shell, 36mm × 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.
| BSA | Italian | |
|---|---|---|
| Full name | BSA / English Threaded | Italian Threaded |
| Fitment | threaded | threaded |
| Shell | 34.8mm shell, 1.37" × 24 TPI thread | 36mm shell, 36mm × 24 TPI thread |
| Also known as | BSC, English, ISO, 1.37" x 24 TPI | ITA, 36 x 24, Italian thread |
| Frames listed | 234 | 15 |
| Bottom brackets listed | 68 | 15 |
| Guide | BSA compatibility → | Italian compatibility → |
Frequently Asked Questions
Can I fit a Italian bottom bracket in a BSA frame?
No. BSA (34.8mm shell, 1.37" × 24 TPI thread) and Italian (36mm shell, 36mm × 24 TPI thread) are different frame interfaces, so a Italian bottom bracket will not fit a BSA frame. You need a bottom bracket built for your frame's standard.
What is the difference between BSA and Italian?
BSA is threaded (34.8mm shell, 1.37" × 24 TPI thread); Italian is threaded (36mm shell, 36mm × 24 TPI thread). Both are threaded standards, so they differ mainly in shell dimensions and which frames use them.
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.
Open the Builder