Well this got to the point of taking apart the Cilo to check. So I can say:
1) Both my Swiss bikes, a Cilo and a Mondia, have French 25 X 1 headsets. They are marked with a 25 and two other French locknuts I had went on the Cilo steerer.
2) Both are fitted with 22.2 stems and no reaming etc. was done to open up the steerer diameter.
3) The Mondia came new with a TTT Record 22.2 stem.
4) I also had a Motobecane French threaded fork lying around and a 22.2 TTT stem fit it.
So it seems that certain nominally French steerers accept 22.2 stems as built. This may be prevalent for Swiss bikes.
--On Thursday, November 09, 2000, 8:41 AM -0500 Jerry Moos <firstname.lastname@example.org>
> Well I measured pretty carefully with calpers, not just the stem in
> question but known 22.2 amd 22.0 stems for comparison. The bike in
> question has a Campy HS with a flat on the back of the lock washer to
> match the flat on the back of the steerer. Every flatted as opposed to
> slotted steerer I have ever seen was French threaded. I think there are
> only two possibliities:
> A) Swiss bikes use 22.2mm stems even in French threaded steerers.
> B) Swiss bikes used steerers with a flat on the back, despite being
> English threaded. This would seem strange, as they would have to use an
> English/Italian HS but with the washer usually found in a French HS.
> Anyone remember where the thread markings are on Campy NR HSs? This might
> confirm whether the HS is in fact French and I guess I could try actually
> inserting a known 22.2 stem to be sure I didn't mismeasure. Don't have
> to visit my LBS bathroom for the Sutherland's - I have three different
> editions sitting on the shelf.
> Jerry Moos
> CYCLESTORE@aol.com wrote:
> > Boys Boys Boys,
> > French headsets (and steering tubes) are too small for safe
> > installation of 22.2mm stems. As I recall someone suffering from an
> > anal, cranial inversion wanted the French steerer (22.0mm) inner steer
> > tube of his bike to be enlarged to 22.2mm. As I recall over half of the
> > metal would have to be removed-you must remember back in bike school we
> > were taught that French (22.0mm inside) steerer tubes are smaller on
> > the outside as well. They don't have as much metal after the removal
> > of .2mm as you might think.
> > The numbers escape me but I'm sure my good pal Jobst Brandt would have
> > an opinion on the subject or you can look up the nitty gritty details
> > in your bike shop's bathroom copy of Sutherland's when you visit over
> > the weekend.
> > I say having the surprise of once breaking off a steerer tube of normal
> > dimensions and discovering the delights of human flight that reducing
> > this safety (?) margin by more than half would be dangerous and
> > foolhardy.
> > I feel that the Swiss bike mentioned (often they use French fittings)
> > has A) not a French headset, B) A French headset and a French Stem, C)
> > a modified 22.2 to 22.0 stem, D) A mangled steerer tube with 22.2 stem
> > inserted (common), E) A cleverly modified death steer tube with a poor
> > guarantee, or F) this bike features Alien intervention.
> > All kidding aside. Of course these things have all been carefully
> > measured with precision tools by competent list members and all facts
> > noted in Dales Brown's Great Book of facts so my guess is "F", " alien
> > intervention".
> > ALERT! ALERT! ALERT! ......>>.>>>>>......>>>>> Just in from CBS news,
> > Jobst Brandt has called in his read on this subject and is weighing in
> > his opinion. Here we go.
> > Jobst has declared Pat Buchannan the winner in a landslide of the
> > Presidential Race. It seems he has discovered through engineering
> > excellence, protocol and ignoring the facts that the whole
> > Bush-Gore-Nader thing was run by Alien impostors with mind control
> > capability and Pat being the only US citizen left standing in the race,
> > Pat wins by default. On a side note Jobst agrees with Gilbert on the
> > Alien side plot to seed classic cyclists with Swiss bikes with the dual
> > whammy of French headsets with ISO(22.2mm) steerers. Improbable but
> > true.
> > Gilbert"where is the broom wagon in this election"Anderson
> > In a message dated 11/9/00 3:27:32 AM, email@example.com writes:
> > << Yes, a Mondia I used to own which was 22.0. I owned the bike in the
> > early 70's, it was probably made between 1967 and 1970.
> > David feldman
> > ----------
> > >From: Jerry & Liz Moos <firstname.lastname@example.org>
> > >To: Classic Rendezvous <email@example.com>
> > >Subject: [Classicrendezvous] Swiss bikes and stems
> > >Date: Wed, Nov 8, 2000, 6:34 PM
> > >
> > >For those who may run across an old Swiss bike, I measured my 1969
> > >Allegro Special and found that Joe was right - even Swiss bikes with
> > >French HSs have 22.2mm stems. At least this is true for two of his
> > >bikes and one of mine. Does anyone has an example that contradicts
> > >this?
> > >
> > >Regards, >>