Re: [CR]Stem expander thread

(Example: Framebuilders:Chris Pauley)

Date: Sat, 16 Jul 2005 04:29:49 -0700 (PDT)
From: Jerome & Elizabeth Moos <>
Subject: Re: [CR]Stem expander thread
To: dddd <>, Classic Rendezvous <>
In-Reply-To: <003301c5898b$52895ac0$933e7343@yoursz6x6sefxo>

Last night, I took the expander wedges from TTT, Cnelli and AVA stems to the hardware store. Neither an M8 x 1.25 standard pitch, nor an M8 x 1.00 fine pitch works. The AVA is the closest, as it does appear to be M8 and an M8 will go in 1 or 2 turns, but then tightens up. Obviousy the pitch is something other than 1.00 or 1.25. The Cinelli and TTT appear to be the same and both appear to be slightly smaller than M8, which won't go in at all. Is a thread diameter measured to the base of the thread or the crest? If the base, perhaps they have a greater thread height that increases their effective diameter to more than that of a standard pitch M8. I tried English bolts, but 1/4 is too small and 5/16 is too largel. 9/32 might have worked, but I don't think there is any such animal, at least not in current production. 9/32 is pretty close to 7mm, so maybe it is M7, but that is not a common size. I think Sheldon's observation that he has never seen a European binder that is a standard thread dimension is being born out here.


Jerry Moos Houston, TX

dddd <> wrote: M7 X 1.0mm is commonly used on newer Taiwan-made stems, at least for the clamp bolts and some expanders, notably of the Profile brand.

I just checked a 1A stem and this appears to be M8 X 1.0 At least my caliper gives an OD of 7.9mm for the aluminum expander bolt. Aren't Campy Super Record post bolts also this very size?

David "Anticipating tomorrow's 6AM Fairfax vintage swap" Snyder Auburn, CA USA

----- Original Message -----
From: "Jerome & Elizabeth Moos"

> Yes, I checked Cinelli, TTT and an old AVA last night, and none match the
> M8 x 1.25. The Cinelli and TTT seem to me to be smaller than M8, but not
> as small a M7 (plus I,m not sure anyone makes M7 bolts). Is it possible
> Cinelli and TTT use an English bolt?
> Regards,
> Jerry Moos
> Ken Freeeman wrote:
> I just went to the box o' stems to compare a Technomic and a Cinelli 1/A.
> No go! Diameter looks the same, but the Cinelli thread looks like a finer
> pitch, and possibly the thread depth is less (a result of the pitch?).
> Ken Freeman
> Ann Arbor, MI
> -----Original Message-----
> From: Jerome & Elizabeth Moos
> Subject: [CR]Stem expander thread
> I've just cut down a Nitto Technomic stem that was too long for a headtube
> on a 53cm frame with the bars set fairly low. Problem is, the expander
> bolt
> is only threaded the last few cm, so if I cut it to match the reduced stem
> length, I will cut off the threaded section. Fortuitously, it happens the
> Nitto expander uses a standard M8 x 1.25 thread and I've found a net site
> that sells stainless M8 x 1.25 socket head cap screws as long as 140mm,
> which should be sufficient. I will probably order one or two, but if these
> will work for most European and Japanese stems, I may order several more.
> Does anyone know if the M8 x 1.25 thread is common to all major European
> and
> Japanese stem expanders? Or does it vary from brand to brand? I imagine
> the older UK stems are probably English thread.


> Regards,


> Jerry Moos