Threaded 1 1/8th TPI differences.

[Spankyfart]

I'm trying to install an M900 XTR headset with a Marin Rockstar spinner fork.
Yeah, that doesn't work for reason, now a little google search comes up with this.

M900

Headset Type - 1 1/8" Threaded (Standard 26 TPI)
Cup Size (OD) - 34.0 mm
Crown Race (ID) - 29.9 mm
Stack Height - 37 mm

Marin

Threading / Gewindesteigung:
28.6mm x 26 TPI

These numbers do not come from official sites, my question is this; are the threadings on forks different?
An old Ritchey locknut didn't fit either, the old locknut goes on without hassle.

I'm at a loss.

 

[Spankyfart]

From a wikipage,
The thread pitch is usually 24 threads per inch except for some old Raleighs which use 26.
The internet is doing my head in.

 

[hamster]

I think that's dud info on 26tpi. I've never encountered anything different in 1 1/8". I used several different headsets on a 1994 Marin fork and never had a problem.

 

[Sir Neil d'Menture]

I thought they were all 24tpi.

 

[Spankyfart]

Well what can I tell you, they won't fit.
I have another fork, have to find it first.
And test if that works, it's the weirdest thing.

 

[Spankyfart]

Well all the locknuts on the other fork went on smoothly, so the thread is busted.
Managed to force the first ring on there, never good to see bits off aluminium scrape out the threads....

Case closed.

 

[Sir Neil d'Menture]

Get a mini hacksaw blade and run it round the threads especially near the top. Often opens up the threads.

 

[Tootyred]

Use an old rubbish steel headset top race first. I keep a few for just that purpose....especially if the forks have been rattling around a shed for donkeys years getting bashed.

Steel on steel will clean the treads.....steel forks on aluminium xtr headset......i foresee tears before bedtime.....

 

[Spankyfart]

I used a ritchey steel one first, went on rough but I got it on fully.
Then I used the XTR one, went on sorta rough but there weren't flakes of aluminum flying around, it's fine

 

[elite504]

Use an old rubbish steel headset top race first. I keep a few for just that purpose....especially if the forks have been rattling around a shed for donkeys years getting bashed.

Steel on steel will clean the treads.....steel forks on aluminium xtr headset......i foresee tears before bedtime.....

^^ This.
One thread pitch for 1 1/8"
There are indeed two for 1" if you include old raleigh. We'll ignore french and swiss for the moment as they were never used an MTBs

Chase thread with a steel nut, a thread file, or get a shop to run a proper die down it. This is still a cheaper option than screwing an XTR component.