It’s possible that the history of ZZR (and Romet) goes something like this...

In 1948 the new communist government in Poland nationalised the major bicycle manufacturers, amalgamating them into a single company, possibly called ZZR. ZZR stands for Zjednoczonych Zakładów Rowerowych which might translate as something like ‘Amalgamated State Bicycle Company’. ZZR ended up with a motley assortment of factories in Bydgoszcz, Poznan and Czechowice-Dziedzice. During this process, ZZR may have had something to do with (or grown out of) Pafaro.

By 1953 ZZR had decided that its main bicycle brand would be called Romet and that its main bicycle manufacturing facility would be in Bydgoszcz. However, it continued to manufacture bicycles under the ZZR brand probably until the late 1970s.

As far as derailleurs are concerned, I am aware of four basic models:

• A copy of a Huret Competition. I have not been able to find any date for this model, but I own an example, clearly branded ZZR, that I am yet to photograph. My guess is that it is the earliest ZZR model and dates from the mid-1950s.
• A single cable pull-chain design that was a copy of a Simplex Tour de France. This was certainly produced from 1963 to 1967, but may have been produced much earlier (in the 1950s) and a few years later (possibly up to 1970). I do not have one of these in this collection.
• A double cable pull-chain design that was a copy of a Simplex Juy-51. This was certainly produced in 1971 and 1967, but may have been produced a few years earlier (possibly from 1968).
• A parallelogram design that was a copy of the Huret Svelto. This was produced from 1972, and at some point (possibly 1977) was rebranded Romet.

Later derailleurs wer all branded Romet.

Finally I can’t help noting that ZZR would almost certainly be the last entry in any telephone book - it is the antithesis of AAA Car Repairs, A1 Plumbing services, Aaardvaark window cleaners and all those other companies that strive to be at the top of page 1. There’s a certain class to that.