Chuck makes a good point - all the cambio Paris-Roubaix shifters I've seen are equipped with the D-ring (oval ring) end nut. I'll check the 1949 magazines for further details.
The design of the D-ring end nut is really quite nice. Grab one of your old Campagnolo hubs and take a look...
First notice how the D-ring acts as the knob for turning the end nut. The D-ring is strong enough to resist bending under almost any conditions... only once have I ever pulled one apart, snagging it on something during a cyclocross race.
As you unscrew the end nut from the skewer, notice the amount of resistance, but when you get near the end the resistance nearly vanishes. That's the point at which the skewer clears the internal brass pads (steel on later models). The D-ring acts as a spring, preloading the pads against the skewer and keeping the end nut from vibrating and moving around when the wheel is not mounted on the bike (for instance, bouncing around in the trunk of your car, or espacially when the quick release is open during operation of the Paris-Roubaix shifter).
Now turn the end nut over and look at the recessed area on the back. You'll probably see two square indentations/windows. These indentations hold the brass (later steel) pads to keep them from moving too far into the end nut when it is removed from the skewer. Otherwise the pads would go in and the D-ring would fall off.
Well made, not-too-tight and not-too-loose, durable, and nearly indestructable, the D-ring end nut is, I think, a little gem... a bit of subtle engineering design which does it's job extremely well.
The D-ring end nut probably cost more to produce - more parts, more tools required for manufacturing/fabrication and assembly, but it was an "upgrade" and was probably the best choice for inclusion with the top-of-the-line single lever Paris-Roubaix shifter and subsequent hubsets.
Aldo Ross Middletown, Ohio
Aldo Ross wrote:
> On the cambio Paris-Roubaix the adjustment is much more
> critical - if the qr lever engages too soon the indexing
> mechanism can't provide any chain slack, and the shifting
> mechanism can be affected. And just like with the cambio
> Corsa, if it's too loose, the qr can't hold the wheel in
> place.
>
> The adjustability of the frankenstein bolts was (and still
> is) convenient when using these shifters.
Great post Aldo, luv the movies of you shifting... one small point, I believe the 1949 single lever (called the Paris-Roubaix after April 1950)) came with oval-ring on the cone shaped adjusting nut, not the frankenstein bolts. Does anyone know for sure what style adjusting nut originally came on the Paris-Roubaix derailleur?
Chuck Schmidt
South Pasadena, CA USA
http://www.velo-retro.com (reprints, t-shirts & timelines)