Taganrog (2nd style) derailleur

The Taganrog derailleur is a bit like the final year project of a capable engineering student with a love of derailleurs. The Taganrog is very accurately machined, with the look of a product of a CNC machine - but I suspect that there were more humans than computers involved in its manufacture. However, technically irrelevant, but commercially important, factors like the surface finishes are not as refined as you might expect of a more formally marketed product.

All of this is consistent with it being manufactured in the Beriev aeroplane factory, but as a kind of illicit private operation. You can see more information about this here.

The derailleur, itself, is an upmarket aluminium version of the 1970s Shimano Skylark - kind of like a Shimano Crane without the drop parallelogram. Some features that I note are:

It has two sprung pivots, and an overall geometry just like a mid 1970s Shimano Skylark.
The adjustment screws are on the bottom edge of the outer parallelogram plate, just like a mid 1970s Shimano Skylark.
It is made of aluminium, with large headed b-pivot and p-pivot allen bolts, rather like a mid 1970s Shimano Crane.
The cable clamp fitting and the cable adjuster are extremely derivative of those on a mid 1970s Shimano Crane.

But...

The pulley cage and has a mid-century modernist look.
The sprung plate at the b-pivot has a kind of similarity to to an early Mavic 800.
Most examples are hard-anodised in an undyed 'antique bronze' finish.
The lack of tacky branding is surprisingly refreshing.

And finally...

I have, above, blithely said that Taganrog derailleurs have two sprung pivots like a Shimano (or Simplex) design. However, the b-pivot spring on a Shimano or Simplex derailleur drives the p-pivot towards the rear of the bicycle, contributing to chain tension. In contrast, all three of my Taganrog derailleurs are set up so that the b-pivot spring drives the p-pivot forwards - towards the front of the bicycle. The purpose of this is, as yet, unclear to me.

Based on not very much, I think that this is a mid period Taganrog derailleur. Some of its features include:

The outer parallelogram plate has a plain face with no 'weight-saving' channel.
The main allen bolts are hollow and made of steel.
The flat sprung plate at the b-pivot is relatively small.
Only one of the parallelogram pivots is removable and is held in place with a circlip. The other three parallelogram pivots are rivetted.
The p-pivot spring fits in the same way as on my Taganrog (3rd style) derailleur.
It is anodised in a particularly bilious example of Taganrog's signature hard-anodised, undyed, 'antique bronze' finish.

On this example, I think that the low gear adjustment screw may not be original.