These four stamps are from a set published by the Russian Post Office in 2008. They are of some interest to equipment nerds because they are all about the bike itself (not cycling or cyclists in general) and even feature selected details of equipment. The actual size of each stamps is 50mm by 38mm.
Scan 3 shows what appears to be a military folding bicycle from 1917 manufactured by ‘Leutner’. In 1915 Alexander Leutner & Co. were evacuated from Riga to Kharkov, and went on to become the Kharkov bicycle works. This model would therefore have been produced in Kharkov.
However, for the derailleur enthusiast the meat is all in scan 1. It features the legendary ZICH-1 three speed derailleur bicycle from 1946. Even more impressive is the image of the derailleur itself - a clear clone of a Simplex touring derailleur of the time.