John Barron wrote:
>
> I decided that it's time for me to contribute a teeny bit to the group,
> so I took some pictures and rambled on a bit about some subtle
> variations of the Campagnolo Gran Sport front and rear derailleurs.
>
> http://www.velostuf.com/
Thank you, thank you, thank you John. (Great, now we have to look for "loopy L" on the front derailleur cage! I missed that subtlety.)
There have been quite a lot of subtle and not so subtle modifications to the Gran Sport over the years and below is what I have been able to figure out with the help of many list members (thank you all).
----------------------------------------------------------------------------------
Here's the current version of info from the Campagnolo Timeline about Gran Sport derailleurs:
1949 -- The Gran Sport twin cable, parallelogram rear derailleur prototype is shown at the Paris Show.
1950 -- The Gran Sport twin cable, parallelogram rear derailleur prototype is shown at the Milan trade show.
1951 -- The Gran Sport single cable, parallelogram rear derailleur (chromed bronze, large chromed mounting bolt and pivot bolt and holes in pulleys, set screw-style cable clamp) paired with bar-end shifters without rubber covers (no down-tube shifters originally) and Gran Sport sliding rod, cable operated front derailleur are introduced.
1952 -- The Gran Sport Extra rear derailleur (second generation of Gran Sport) is introduced (changed body, large chromed mounting bolt and pivot bolt, holes in pulleys, extended horn shape to the outside pulley cage frame and revised cable clamp).
1953 -- In August the definitive Gran Sport rear derailleur (third generation of Gran Sport) is introduced: changed body, pulley cage reverts to first version, no holes in pulleys, smaller black-oxide mounting bolt and pivot bolt, 5mm spring cover (was 3.5mm).
1956 -- Gran Sport rear derailleur with the lower body and outer cage revised (elimination of three of original six spring tension adjustment holes) and an 8mm spring cover (was 5mm).
1958 -- Around this time the Gran Sport rear derailleur has its cable tension adjustment screw eliminated and the pulley cage stop screw is countersunk into the lower body.
1961 -- In July a revised Gran Sport rear derailleur is introduced with a 10mm spring cover (was 8mm) to improve shifting on six-speed freewheels.
1963 -- In October the Record rear derailleur (chrome plated bronze) is introduced. This has a revised cage shape with the pivot behind and closer to the jockey pulley and center punched rivets.
-----------------------------------------------------------------------------------
Note that the most obvious visual clue to these derailleurs is the thickness of the spring cover!
The biggest mystery was when exactly the cable tension adjustment screw was eliminated (1958 is just my educated [debated by some] guess).
PLEASE! The rest of you out there in lurkingland; help us out here with your corrections/observations!!!
Chuck Schmidt
South Pasadena, Southern California
http://www.velo-retro.com (complete Campagnolo Timeline on site)