French forks ?

[anern]

Hi,
Had some problems with stipped threads on the lock nut on by headset,
both second hand bolts but now I've decided to do the job properly I'm
concerned that I may have french forks. Sheldon's site says that the filed
bit on the back of the top of the fork threads is a french thing - everyone
else having a slot. The table on the site says this has a different TPI of
25.4 rather than the ISO standard 24. Photo here :

http://homepage.ntlworld.com/brucejlee/BikePhotos/P1000968.JPG


site page here

http://sheldonbrown.com/gloss_ha-i.html#headset

My LBS said maybe the thread on the fork was dodgey but it seems OK to me,
he recommended a 105 headset.

Also, are there different head tub diameters ? This is an old frame so would
a modern headset fit ?

Cheers,

Bruce.

[_[_2_]]

On Sat, 19 Apr 2008 15:07:35 GMT, anern wrote:

> Hi,
> Had some problems with stipped threads on the lock nut on by headset,
> both second hand bolts but now I've decided to do the job properly I'm
> concerned that I may have french forks. Sheldon's site says that the filed
> bit on the back of the top of the fork threads is a french thing - everyone
> else having a slot. The table on the site says this has a different TPI of
> 25.4 rather than the ISO standard 24. Photo here :
>
> http://homepage.ntlworld.com/brucejlee/BikePhotos/P1000968.JPG
>
>
> site page here
>
> http://sheldonbrown.com/gloss_ha-i.html#headset
>
> My LBS said maybe the thread on the fork was dodgey but it seems OK to me,
> he recommended a 105 headset.
>
> Also, are there different head tub diameters ? This is an old frame so would
> a modern headset fit ?
>

Measure the stem - if 22.0, French. If 22.2, not French.

What's the make and age?

[anern]

> > Hi,
> > Had some problems with stipped threads on the lock nut on by
headset,
> > both second hand bolts but now I've decided to do the job properly I'm
> > concerned that I may have french forks. Sheldon's site says that the
filed
> > bit on the back of the top of the fork threads is a french thing -
everyone
> > else having a slot. The table on the site says this has a different TPI
of
> > 25.4 rather than the ISO standard 24. Photo here :
> >
> > http://homepage.ntlworld.com/brucejlee/BikePhotos/P1000968.JPG
> >
> >
> > site page here
> >
> > http://sheldonbrown.com/gloss_ha-i.html#headset
> >
> > My LBS said maybe the thread on the fork was dodgey but it seems OK to
me,
> > he recommended a 105 headset.
> >
> > Also, are there different head tub diameters ? This is an old frame so
would
> > a modern headset fit ?
> >
>
> Measure the stem - if 22.0, French. If 22.2, not French.
>
> What's the make and age?

I haven't got anything to measure to that acuracy. I think the bikes a Claud
Butler touring bike which was why I was confused about the forks, the forks
may not be origonal - I think the bike may have been repainted.

[Pete Biggs]

anern wrote:
> Hi,
> Had some problems with stipped threads on the lock nut on by
> headset, both second hand bolts but now I've decided to do the job
> properly I'm concerned that I may have french forks. Sheldon's site
> says that the filed bit on the back of the top of the fork threads is
> a french thing - everyone else having a slot. The table on the site
> says this has a different TPI of
> 25.4 rather than the ISO standard 24. Photo here :
>
> http://homepage.ntlworld.com/brucejlee/BikePhotos/P1000968.JPG
>
>
> site page here
>
> http://sheldonbrown.com/gloss_ha-i.html#headset
>
> My LBS said maybe the thread on the fork was dodgey but it seems OK
> to me, he recommended a 105 headset.
>
> Also, are there different head tub diameters ? This is an old frame
> so would a modern headset fit ?

Sheldon in effect mentions the head tube diameter too on that table. It's
the same (or almost) as the Frame Cup Outside Diameter. You're likely to
have 30.2mm - which a modern 1" headset will fit.

Actually the head tube is a tiny bit smaller than the cup to get a press
fit.

~PB

[Rob Morley]

In article >, anern
says...
> Hi,
> Had some problems with stipped threads on the lock nut on by headset,
> both second hand bolts but now I've decided to do the job properly I'm
> concerned that I may have french forks. Sheldon's site says that the filed
> bit on the back of the top of the fork threads is a french thing - everyone
> else having a slot.

Plenty of standard forks have flats rather than slots - yours looks as
if it was filed by hand anyway, so probably a universal replacement or
hand built item.

> The table on the site says this has a different TPI of
> 25.4 rather than the ISO standard 24.

Just measure and count.

> Photo here :
>
> http://homepage.ntlworld.com/brucejlee/BikePhotos/P1000968.JPG
>
> site page here
>
> http://sheldonbrown.com/gloss_ha-i.html#headset
>
> My LBS said maybe the thread on the fork was dodgey but it seems OK to me,
> he recommended a 105 headset.

If the adjustable race has been loose for a while it may have deformed
the thread, so it's undersize but still looks fine - take the fork out
and place a straight edge along the thread (or just feel it) to see if
it narrows where the race was.
>
> Also, are there different head tub diameters ?

That's the "frame cup diameter" in Sheldon's table.

> This is an old frame so would a modern headset fit ?
>
IME the crown race seat diameter isn't as standard as it should be on
some forks - if it's a loose fit you'll need to source another race or
complete headset, if it's tight don't press it too hard - it's supposed
to be an interference fit but some are oversized and you could break the
race.