Readers of this blog will know that we recently purchased an Italian "Nicoletti" bicycle originally built in 1959 or 1960 (according to the builder's son). The bicycle was mostly complete--only a few pieces were not original to the bike.
One of those pieces was the Campagnolo "Velox" derailleur which, while being somewhat unusual, dated to about a decade after the Nicoletti was built. We inquired with the Nicoletti shop (still in business in Verona), and they responded that the Velox was, indeed, not original. The bike's original derailleur, they said, would have been a Campagnolo Sport.
So ... off we went to eBay in search of a Sport, eventually finding a very nice example from an international seller in Rome, Italy. After a few weeks' wait for our package to arrive, we were finally in possession of a true Campagnolo anachronism--a rear derailleur with a single pulley.
We installed the Sport today, in the process returning the Nicoletti to a condition ever closer its original state.
Amazingly, despite having only one pulley, the derailleur shifts reasonably well. The lack of an articulated two-pulley cage severely limits the derailleur's ability to handle wide ranges in cog teeth--the markings on the back suggest a limit of 16 to 22 teeth (the Regina freewheel on our Nicoletti is a four-speed, with 15t and 22t small and large cogs).
More photos of the bike with the Sport installed are available after the break. A video is coming soon.