Moving the wheel to the back of the DO usually helps. To allow the Campy NR RD on an early 80's Trek 660 to clear a 28T cog, I not only moved the w heel to the back of the DO, but completely removed the wheel stops to allow it to come that little further back. This bike has the newer short Camp y DO's. If it had had the older long Campy DO's I could probably just ha ve run the wheel stops all the way back, but left them installed.
Regards,
Jerry Moos
Big Spring, Texas, USA
From: travis.harry@gmail.com <travis.harry@gmail.com> Subject: Re: [CR]Max sprocket for Huret Jubilee long cage? To: Classicrendezvous@bikelist.org Date: Monday, September 8, 2008, 4:38 PM
You have experience of observing and recording the "natural history" of these creatures:
For those with long semi-horizontal dropout slots, would you comment on the role of axle placement for the operation of the rear der? Assume you add an inch (25mm) of chain to move the axle 1/2" (25mm)back in the slot, so relative chain tightness has not changed, have you increased or diminished the capacity of the rear der to handle a larger largest cog?
Asking this here because I don't think it is covered in say the Sheldon Collection, beyond the general race-based observation that shorter wheelbase --> more precise handling.
Harry Travis Washington, DC USA
, stirred by:
Jerome & Elizabeth Moos <jerrymoos@sbcglobal.net>'s message
of:
Monday 08 Sep 08 at 01:40 PM,
On: Re: [CR]Max sprocket for Huret Jubilee long cage?
[echoed below, in part<=1]
-oOo-
>Even the short cage Jubilee has a surprisingly wide range, I'm using
>one wi th a 28T cog on my early 70's Raleigh Competition, and another
>on an even l arger cog, 32T I think, on my Raleigh Super Tourer.
>ÿ
>However, I've found there are two considerations in regard to what
>gears an
> RD will shift.ÿ The first is how much chain the cage will wrapÿbetw
een
> the rear stop and the point where the cage becomes too nearÿhorizonal
ÿ
>on the large-large combo to let the chain run smoothly.ÿ Simplex RD's
>hav e a rangeÿadvantage because the sprung upper pivot allows the
>derailleur body to rotate further forward, so that the body rotation
>as well a cage ro tationÿwraps chain.ÿ How much chain an RD will wra
p
>isÿa function of RD geometry and whether the upper pivot is sprung.
>ÿ
>But the second consideration, which often is the limiting one,
>isÿwhether
> the upper pulley will hit the large cog or come so close that the
>chain wo n't run smoothly.ÿÿThis one is a function not only of RD
>geometry, but also dropout geometry, chainstay length, chain length
>and front chainring s ize.ÿ If the pulley hits the large cog,ÿit is
>often because the cage is
> near vertical, when the chain is on theÿlarge cog.ÿ This can often
be
>solved by either lengthening or shortening the chain to rotate the cage
>eit her forward of back, and in either caseÿdown.ÿ But this can then
>cause the chain to be slackÿon the small-small combo or the cage to b
e
>near hor izonal on the large-large.ÿ One may then be forced to either
>use a larger
> small cog or a smaller large chainring.ÿ I find I usually choose to
>shor ten the chain and fit a smaller large chainring, typically
>substituting a 5 0Tÿfor a 52T or 53T.ÿ In fact, I just happened to g
o
>through this drill
> with a
> mid-70's Raleigh Gran Sport yesterday.
>ÿ
>Regards,
>ÿ
>Jerry Moos
>Big Spring, Texas, USAÿÿ
>--- On Sun, 9/7/08, John Thompson <johndthompson@gmail.com> wrote:
>From: John Thompson <johndthompson@gmail.com>
>Subject: Re: [CR]Max sprocket for Huret Jubilee long cage? To:
>Cc: classicrendezvous@bikelist.org
>Date: Sunday, September 7, 2008, 9:25 PM
>Mitch Harris wrote:
>>> Has anyone here used a long cage Jubilee with anything larger than
>>> 24T? If so, what's the largest toot count it can safely /
>reasonably
>>> handle?
>> My short cage Jubilee der works easily with a 28 cog, and I remember
>> them in the 70s specced on bikes with 28 large cogs.
>I think this may also depend on the dropout. I have a short-cage
>Jubilee mounted on a Tange TR dropout
>(http://www.os2.dhs.org/~john/dropouts/tange-tr.jpeg) and it barely
>clears the upper pulley with a 23T cog.
>Further accommodation may be possible by adjusting the "angle of the
>dangle" if your mounting bolt kit includes an adjusting screw, but
>changing the angle too much will adversely affect shifting.
HPT -- ----------------------------------------------------------- travis.dot.harry.trying.gmail.com DemostiX