Re: [CR]RE: smallest chain ring on Campy 144

(Example: Framebuilders:Pino Morroni)

From: "Olof Stroh" <olof@stroh.nu>
To: "Jerome & Elizabeth Moos" <jerrymoos@sbcglobal.net>, "Bob Freitas" <freitas1@pacbell.net>, "CLASSIC RENDEZVOUS" <classicrendezvous@bikelist.org>
References: <20060620192140.32520.qmail@web82215.mail.mud.yahoo.com>
Subject: Re: [CR]RE: smallest chain ring on Campy 144
Date: Tue, 20 Jun 2006 21:52:08 +0200
reply-type=original

Look at http://www.highpath.net/cycles/notes/pcds/05a.html and adjacent pages.

cheers

Olof Stroh
Uppsala Sweden


----- Original Message -----
From: Jerome & Elizabeth Moos
To: Bob Freitas


<classicrendezvous@bikelist.org> Sent: Tuesday, June 20, 2006 9:21 PM Subject: Re: [CR]RE: smallest chain ring on Campy 144


> Speaking of smallest chainrings, I just received, bought from UK eBay,
> several modern Stronglight 130 BCD 38T rings. I'd usually seen 39T listed
> as the smallest ring for 130 BCD. I do note however that Sheldon's web
> site lists 38T as the smallest for 130 BCD.
>
> This makes me wonder about the smallest ring listed for other circles.
> With 1/2" pitch chain, you should have to reduce the chainring
> circumference by 12.7 mm to reduce the smallest ring by one tooth. If you
> divide this by PI, you get a 4.04 mm reduction in BCD for a 1 tooth
> reduction. So, assuming 38T is indeed the absolute minimum for 130 BCD,
> then the 128 BCD old Nervar circle is still limited to 38T, as Sheldon
> lists it, 2 mm reduction in BCD being insufficient to reduce the teeth by
> one.
>
> But Sheldon's list and every other list I have ever seen, including one
> on the modern Stronglight ring packaging, shows 38T as the minimum for the
> 122 BCD old Stronglight circle. This would seem to defy geometry. If a
> 130 BCD will handle 38T, then an 8 mm reduction to 122 BCD should
> certainly allow 37T and probably 36T.
>
> Anyone ever seen a 36T or 37T Stronglight ring? Stronglight definitely
> made rings with odd numbers of teeth, so why not 37T? Also, even though
> 38T is shown as the smallest for 128 BCD Nervar, I've never seen one
> smaller than 40T. Has anyone else?
>
> Regards,
>
> Jerry Moos
> Big Spring, TX
>
>
>
>
> Bob Freitas <freitas1@pacbell.net> wrote:
> Having just bought my second Campagnolo 36t chainring in less than a
> week ($10 no less!) we seem to have skipped over the fact that Campy did
> do a tripple with a small inner ring that was not attached to the 144
> bcd holes but to a set of drilled 100 bcd holes on the spider itself.
> other alternatives would be to drill to one of the current bcds for a
> more complete range of rings.
> more alternatives would be a tripplizer ring which attaches a second
> ring to the inner 144bcd (I have a Merz version which does TA
> cyclotourist down to what 26T)
> BOB FREITAS
> Thinking this cat is skinned in MILL VALLEY,CA