The left-hand side of a classic bottom bracket often outlasts the axle, but finding the correct thread pattern is what separates a smooth restoration from a stalled one. This STRONGLIGHT BP18 cup carries a 35x100 "Français" thread, the standard found on many older French steel frames. As the photos form part of the description, the condition shown is part of the record: the cup is listed with no oxidation.
Why this cup matters for a French-thread rebuild
A steel cup with a 35x100 French thread is not interchangeable with BSC or Swiss cups. Using the wrong pitch can damage the shell on a period frame, so matching the original standard is essential. The STRONGLIGHT BP18 profile sits flush against the non-drive side bearing, keeping the axle alignment clean and the adjustment stable.
Key specifications
- Oxidation: No
- Material: Steel
- Bottom bracket thread: 35x100 "Français"
- Manufacturer part number: 0000
For a matching right-hand cup, compare the STRONGLIGHT Competition right-hand cup with the same thread standard. If the full assembly is what you are chasing, the left-hand Competition cup documents a very close STRONGLIGHT profile.
A small part with a specific fit
What looks like a simple threaded shell is actually a compatibility gate. The 35x100 designation locks this cup to French-bottom-bracket frames, so confirming the shell width and thread direction on your bike before fitting is the correct starting point. For a comparable French-thread bottom bracket unit, the STRONGLIGHT Competition triple shows how the complete assembly comes together.
FAQ
What thread standard does this STRONGLIGHT BP18 cup use?
It uses a 35x100 "Français" bottom bracket thread. This standard is specific to many older French steel frames.
Is this left cup suitable for a modern bottom bracket?
No. The 35x100 French thread is a vintage standard and does not match modern BSC, Italian, or Swiss bottom bracket shells.
What material is the STRONGLIGHT BP18 cup made from?
The cup is made from steel. The technical specifications list the material as steel with no oxidation.
Does this item show any oxidation?
No, the condition data lists oxidation as "No". The photos also form part of the description for checking the exact finish.
Will a right-hand cup work on the left side of the frame?
No. This BP18 is a left-hand cup with a specific thread orientation. A right-hand cup should not be fitted to the left side.
