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Date: 18 Jun 2007 18:23:36
From: still me
Subject: Actual Stem Size Measurments - vintage quill
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I'm trying to figure out if a few stem's I have are sized for 22.0 or
22.2. (In true biking tradition, they bear on diameter information :-)
Two are French manufacture, one is an SR that may have come from a
French bike.
I measured them with a micrometer and got the following sizes: .870,
.871 and .860. Those translate to 22.12, 22.098, and 21.844 mm.
So, should I assume that these are 22.2, 22.2, and 22.0 and just sized
a little under for clearance? Or are the 22.1 ish stems just French
and a little over? How precise are these usually ?
Thanks,
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Date: 18 Jun 2007 12:51:02
From: * * Chas
Subject: Re: Actual Stem Size Measurments - vintage quill
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"still me" <wheeledBob@yahoo.com > wrote in message
news:k1jd73pn5iidsch9u481fg31jsk0hmf3nl@4ax.com...
> I'm trying to figure out if a few stem's I have are sized for 22.0 or
> 22.2. (In true biking tradition, they bear on diameter information :-)
> Two are French manufacture, one is an SR that may have come from a
> French bike.
>
> I measured them with a micrometer and got the following sizes: .870,
> .871 and .860. Those translate to 22.12, 22.098, and 21.844 mm.
>
> So, should I assume that these are 22.2, 22.2, and 22.0 and just sized
> a little under for clearance? Or are the 22.1 ish stems just French
> and a little over? How precise are these usually ?
>
> Thanks,
On most post 1970 sporting bikes the bore of English (1"-24TPI ) and
Italian ( 25.4x24TPI ) threaded steering tubes "should" be .875" or
22.225mm.
Stems for these bikes "should" be 22.2mm or .874 which is slightly
undersize to allow a slip fit.
French or Metric standard bikes with 25mm x 1mm threads are supposed to
use a 21.9mm or nominal 22.0mm stem to go into a 22mm bore, again
undersized for a slip fit.
In reality these dimensions are all over the place. I have over a dozen
classic Cinelli 1/A and 3TTT stems including some real 21.9mm and 22mm
ones factory installed on French bikes.
The quill sizes of these stems range from 21.9mm to 22.23mm measured with
a digital micrometer.
The bore sizes in the steering tubes on my retro bikes have measured from
21.9mm (1974 Raleigh Pro - the bore wasn't masked when the fork was
painted) to 22.3+ ( late 80s Colnago).
I've seen a few real metric 21.9mm sized Japanese stems made for French
bikes.
Motobecanes were originally metric threaded bikes and some of them used
Swiss threaded BBs. At some point in the late 1970s many French bike Mfgs.
switched to English or "ISO" threads but there was never a real true
standard that makers stuck to.
I have a 1982-3 Motobecane Team Champion frame with metric Columbus
tubing, a French BB and an English fork and headset.
Seat posts are just as bad.....
Now does that clear things up?
Chas.
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Date: 18 Jun 2007 21:02:07
From: still me
Subject: Re: Actual Stem Size Measurments - vintage quill
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On Mon, 18 Jun 2007 12:51:02 -0700, "* * Chas"
<verktygjunk@aol.spamski.com > wrote:
>Now does that clear things up?
Yeah, thanks, clear as mud!
:-)
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