Thanks, Sheldon, for your informative reply. I may have misunderstood my mechanic, or perhaps he misquoted his research findings.
It's possible that the threads didn't continue to the shoulder; I'll examine this.
I've discovered also that Surly's cogs are ISO threaded. I'll have to see if my hub threads are salvagable. If so, perhaps I'll try a Surly cog (the previous was a SunTour). I expect, though, that I'll need a new hub, and it's likely you're correct about the quality of its threads in the first place. Too bad; the bearings were wonderfully smooth and it looked like a quality item.
Thanks again.
Kris Green
On 9/12/05, Sheldon Brown <CaptBike@sheldonbrown.com> wrote:
> Kristopher Green wrote:
> >Last week I sent a desperate email missive requesting information on
> >why a NOS Gipiemme track hub I'd had built up that was stamped
> >"Special ISO" permitted a standard Suntour cog to be threaded on by
> >hand, but allowed that cog to spin impotently across the threads the
> >moment leg power was applied.
> >
> >Thanks to those who replied, but the correct answer actually came from
> >my local mechanic, framebuilder Bill Stevenson, who is a great source
> >of wisdom, a good friend, and the anchor for our local road riding
> >scene. Like me, he found nothing online, but an old Sutherland's
> >manual revealed that the ISO standard did actually differ from
> >longstanding cog threading conventions. In this case, ISO adopted the
> >same pitch and diameter as that used for French bottom bracket cups.
>
> I don't believe that's correct.
>
> My 4th and 7th edition Sutherlands' agree that ISO DIS 6698 specifies
> 1.375 (34.92 mm) x 24 tpi, 60 degree. This is for freewheels, but
> there is no separate listing for fixed sprockets.
>
> This is the same as the ISO DIS 6696 standard for bottom bracket threads.
>
> Old English standard is 1.370 (34.80 mm), 5 thousandths smaller.
> This is not generally enough to matter, but if that was the nature
> of the mismatch it would make an English sprocket a slightly tighter
> fit on an ISO hub.
>
> French bottom brackets are larger, 35 mm (1.378"), with a slightly
> finer 1 mm (25.4 tpi) pitch.
>
> If the hub was this size, you wouldn't be able to fit an ISO or
> English sprocket onto it.
>
> I think the hub was marked "Special ISO" to distinguish it from the
> obsolete Italian size, 35 mm x 24 tpi.
>
> >Longtime shadetree mechanics will recall that English cups will thread
> >into French BB shells pretty nicely
>
> English inside, French outside...that can "work." French inside,
> English outside, no go.
>
> >(the cog went onto my hub like it
> >was buttered), but that they won't stay put in use.
>
> do the threads on the hub run pretty much all the way to the
> shoulder? Sometimes you can run out of engagement on a hub because
> the threads usually stop somewhere short of the shoulder. This is
> more often a problem with low-quality, thin stamped sprockets.
>
> Given the general quality level and reputations of the brands
> involved, my guess is that the Gipiemme hub is defective. This is
> not a brand noted for quality.
>
> Sheldon "ISO" Brown
> Newtonville, Massachusetts
>
> --
> Harris Cyclery, West Newton, Massachusetts
> Phone 617-244-9772 FAX 617-244-1041
> http://harriscyclery.com
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> http://sheldonbrown.com
>
-- Kristopher Green Software Application Analyst/Designer Johnson, Bassin, & Shaw International 219 Legion Way SW, Suite 203B Olympia WA 98501-1297 360.754.2928
--
Kristopher Green
Software Application Analyst/Designer
Johnson, Bassin, & Shaw International
219 Legion Way SW, Suite 203B
Olympia WA 98501-1297
360.754.2928