That sounds convincing. All I can say from experience is that, in my experience, this combination works best when you have the long horizontal dropouts and relatively long chainstays.
Granted, you need the long dropouts to move the axle back behind the derailleur's mounting bolt. But I've never needed to move the wheel as far back as some messages have suggested. I.e. I've never needed to remove the dropout positioning screws, reverse them, light votive candles or anything of that nature.
And from empirical observation, I've seen that things worked best with long chainstays - perhaps because of the factors mentioned by Ken. Could it just be coincidence? I.e. I've never worked on an older bike with verirtical dropouts, so anything with long chainstays coincidentally also had the longer dropouts.
Suffice it to say, for me, this combination works if you're
reasonable about what sort of chainring combination you place
on the crankset.
Your mileage may vary,
Fred Rednor - Arlington, Virginia (USA)
> I think the effect of short chainstays is when the chain is
\r?\n> tight on a
\r?\n> big-big setting. The cage rotates to near-horizontal and the
\r?\n> idler wheel
\r?\n> moves forward by perhaps an inch, half the length of the
\r?\n> cage. This
\r?\n> enhances chain angularity, putting added side tension on the
\r?\n> chain/idler
\r?\n> wheel interface as the chain enters the cage, and pulls
\r?\n> sideways on the big
\r?\n> chainwheel. Not damaging, but noisy, and I think it has
\r?\n> resulted in a few
\r?\n> thrown chains on my bike. I adjusted it better by moving the
\r?\n> wheel forward
\r?\n> in the dropout, allowing the cage to rotate to a
\r?\n> less-extended position.
\r?\n>
\r?\n> With a longer chainstay tube the effect of this shortened
\r?\n> chain run would be
\r?\n> less than on a tighter frame. Again it probably doesn't
\r?\n> affect how the
\r?\n> chain clears the cog and then climbs on, but the angle itself
\r?\n> could cause
\r?\n> noise that is at least irritating.
\r?\n>
\r?\n> Ken Freeman
\r?\n> Ann Arbor, MI USA
\r?\n>
\r?\n> -----Original Message-----
\r?\n> From: classicrendezvous-bounces@bikelist.org
\r?\n> [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of
\r?\n> Mark Bulgier
\r?\n> Sent: Monday, February 19, 2007 7:48 PM
\r?\n> To: Fred Rafael Rednor; classicrendezvous@bikelist.org
\r?\n> Subject: RE: [CR]28 teeth with Campagnolo Nuovo Record?
\r?\n>
\r?\n> Fred Rednor wrote:
\r?\n> >
\r?\n> > > I've been struggling with 26-13 standard-6
\r?\n> > > speed on my Masi for a while, and I think
\r?\n> > > I got it. This is a really short chainstay.
\r?\n> >
\r?\n> > So perhaps the crucial factor for those of us who have had
\r?\n> success
\r?\n> > setting up the Nuvo Record with a 14-28 (or even a
\r?\n> > 13-28) freewheels was the chainstay length? I've never had
\r?\n> problems
\r?\n> > with this setup but I've never done in on anything but
\r?\n> 1960s (or early
\r?\n> > '70s) frames which had - by latter standards - long
\r?\n> chainstays.
\r?\n>
\r?\n> No, the rear derailleur capacity doesn't really depend on how
\r?\n> long the
\r?\n> chainstays are. Chainstay length does affect how many gear
\r?\n> combinations are
\r?\n> useful, before the chain deflection angle gets too annoying
\r?\n> and/or the chain
\r?\n> rubs on the larger chainring -- but that's not the question
\r?\n> we're looking at
\r?\n> here.
\r?\n>
\r?\n> As several people have pointed out, to get the max range you
\r?\n> do need to be
\r?\n> able to move the wheel in the dropout (thus, forget vertical
\r?\n> dropouts), but
\r?\n> that's to change the distance between the freewheel and the
\r?\n> derailleur, and
\r?\n> to fine-tune the chain wrap. It's not because you're
\r?\n> adjusting the
\r?\n> chainstay length.
\r?\n>
\r?\n> Now there might be chainstay lengths that are better and
\r?\n> others worse.
\r?\n> That's because we can adjust the chain length only 1" at a
\r?\n> time. But it's
\r?\n> not so simple as long=good. It'll be something more like 16,
\r?\n> 16.5, 17, 17.5
\r?\n> and 18 all good, but 16.25, 16.75, 17.25, 17.75 and 18.25 all
\r?\n> bad. (Exact
\r?\n> good & bad lengths varying from bike to bike)
\r?\n>
\r?\n> The idea there might be good and bad lengths is somewhat
\r?\n> doubtful, but it's
\r?\n> based on the fact that when you move the axle in the dropouts
\r?\n> you're
\r?\n> adjusting two things at once: the distance from the freewheel
\r?\n> to the
\r?\n> derailleur, and chain wrap angle of the cage. Maybe there
\r?\n> could be a setup
\r?\n> that requires a certain specific position in the dropout to
\r?\n> get the
\r?\n> freewheel/derailleur distance just right, but then the chain
\r?\n> wrap isn't just
\r?\n> right? Then adjusting the chainstay length a little (if that
\r?\n> were possible)
\r?\n> would provide the independent adjustment of chain wrap.
\r?\n>
\r?\n> Each half-inch longer in the chainstay requires about 1" more
\r?\n> chain.
\r?\n> (Not exactly 1" because the upper & lower chain runs aren't
\r?\n> parallel, but
\r?\n> pretty close.) So the good & bad lengths will repeat for
\r?\n> each half-inch of
\r?\n> chainstay length (roughly).
\r?\n>
\r?\n> I think, in practice, that any chainstay length can probably
\r?\n> be made to work
\r?\n> with a 28 as long as you have long horizontal-slot dropouts.
\r?\n> Maybe at the
\r?\n> very extreme of what a NR can be made to shift, then the
\r?\n> exact chainstay
\r?\n> length may matter a bit. I doubt anyone knows what that
\r?\n> limit really is,
\r?\n> but we know it is at least 31t.
\r?\n>
\r?\n> Mark Bulgier
\r?\n> Seattle WA USA