This is the second of two patents filed by a Boris Mikhailov who appears to work for a mysterious body called Enterprise P/I B-8916 (ПРЕДПРИЯТИЕ П/Я В-8916). To add to the mystery, Enterprise P/I B-8916 held a number of other highly specialist scientific patents that seem completely unrelated to bicycles. As far as I can tell, Enterprise P/I B-8916 may have been based in Zheleznodorozhny, an eastern suburb of Moscow. The word ‘Zheleznodorozhny’ means something like ‘Railway’, and the local railway station is famous as the one at which Anna Karenina threw herself under the wheels of a train - a locally-sourced, pan-seared, goujon of knowledge that could only prove useful in an up-market pub quiz (bistro quiz perhaps?).

This 1979 patent appears to be for a derailleur design that has many similarities to the 1988 Campagnolo Chorus. Crucially it is a dropped parallelogram design that allows you to tilt the parallelogram and provides handy markings to help you to do so. Say it quietly, but I believe that Campagnolo did have extensive contacts with the Soviet cycling authorities and may possibly have been aware of this patent.

There are also differences between this design and that of the Campagnolo Chorus. As well as providing the ability to tilt the parallelogram, this design allows you to raise and lower it to manage the chain gap. It also shows the cable running inside the parallelogram, in the elegant, but fiddly, style of an early SunTour Cyclone.

I have no idea if it was ever produced - regrettably, I suspect not.

• Publisher: Rospatent
• Inventor: Boris Rostislavovich Mikhailov
• Country: Russia
• Date: USSR application filed July 1979
• Derailleur brands: unknown but eerily similar to Campagnolo's designs
• Derailleurs: unknown but eerily similar to Campagnolo Chorus (C010-SM) and Campagnolo Chorus (C010-LG)