The NR derailleur was designed in the days of 4 tooth spreads between outer and inner chainrings, and works extremely well with 52-48 chainrings and the like. When riders started using 10 tooth spreads (42-52) this created a big problem for the rear derailleur. If the chain was short enough to not droop when on the small chainring, the upper pulley is pulled away from the freewheel cogs when the chain is on the large chainring, making for the notoriously poor shifting of the NR rear derailleur when on the big ring in front.
But the problem is solved by the spring loaded upper pivot, which (someone will correct me if I'm wrong) was first made by Simplex. The spring loaded upper pivot allows the derailleur to pivot forward when the chain is on the big ring, which then allows the upper pully to track closer to the freewheel cogs, making the rear shifting just as precise when in the large ring as in the small.
Campy was smart enough to realize this when designing the first Rally derailleur. It was a copy of the Simplex long cage derailleurs. But for reasons that will forever remain mystery, they couldn't bring themselves to add the spring loaded upper pivot to the NR derailleur, until the first C-Record derailleur was introduced, around 1983 + or - a year. And then, inexplicably, they dropped the spring loaded pivot after a year or so and the C-Record derailleur went back the the same pathetic old design of the NR.
Brilliant!
Peter Jon White Peter White Cycles 24 Hall Rd. Hillsborough, NH 03244 603 478 0900 Phone 603 478 0902 Phax Peter@PeterWhiteCycles.com http://www.PeterWhiteCycles.com
> In a message dated 4/20/2003 9:20:39 PM Eastern Daylight Time,
> PeterJonWhite@PeterWhiteCycles.com writes:
>
>
> > I tried it with the cage shown; NR or first generation SR. It didn't
work
> > very well. But with the second generation Super Record cage, it worked
> > quite
> > well. And I sold quite a few in that configuration, starting in whatever
> > year the second generation Super Record plates became available as spare
> > parts; maybe 1980 or so.
> >
> > The stock spring settings were awful and had to be changed. But by
changing
> > the spring settings, you could get good chain wrap over a pretty wide
gear
> > range.
> >
>
> Does this do something that a NR or Super Record couldn't?
> Not sure I understand the "why" of this.
> I put the Rally plates on my NR cause I had it and Bicycle Classics was
> selling the plates cheap!
>
> Pete Geurds
> Douglassville, PA