French threaded fork steerer, are these threads stripped?

Hi all,

I began rebuilding a vintage French bike recently and, after finally sourcing a suitable headset, realised that the adjustable cup won’t go past THAT point (see photo). It really doesn’t look that bad but I can see that a section of the threads are worn and slightly wonky, probably from a loose headset. Is this a simple fix or is my project doomed? I’ve already invested a bit of time into this bike and would hate to have to scrap it. I probably should have checked the threads first (the bb is fine) - lesson learned.

Thanks in advance!
613524
 

midlife

Guru
Is it a steel headset?
 

midlife

Guru
I'd be tempted to use a very narrow triangular file to clean up the threads and them slowly work the race down the threads with plenty of oil. Can't remember ever coming across a French threaded thread cutter.
 
I'd be tempted to use a very narrow triangular file to clean up the threads and them slowly work the race down the threads with plenty of oil. Can't remember ever coming across a French threaded thread cutter.
That's a good shout, I think I might be okay if I can pry those flattened threads apart... No I've not heard of one either, lots of stories of people having to replace the whole steerer then cutting British threads. Thanks for the suggestion!
 

Gillstay

Well-Known Member
That's a good shout, I think I might be okay if I can pry those flattened threads apart... No I've not heard of one either, lots of stories of people having to replace the whole steerer then cutting British threads. Thanks for the suggestion!
I think they are not flattened, but filed off to fit a washer with a internal flat section to stop it rotating when tightening the nuts. From your photo I cannot see why the nuts would not thread down past that section as its out of the way.
 

dave r

Dunking Diddy Dave Pedalling Pensioner
I think they are not flattened, but filed off to fit a washer with a internal flat section to stop it rotating when tightening the nuts. From your photo I cannot see why the nuts would not thread down past that section as its out of the way.
That sounds more likely than worn threads, perhaps theres thread damage around the filed off section.
 
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I think they are not flattened, but filed off to fit a washer with a internal flat section to stop it rotating when tightening the nuts. From your photo I cannot see why the nuts would not thread down past that section as its out of the way.
Yeah, French bikes had this flat section rather than a keyed section for a lock washer. I was talking about the threads below to the left. I actually managed to fix the issue with a very thin file!
 

DRM

Guru
Location
West Yorks
 
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