> Looking for names of 1930s races who started making bicycles after
> they retired - or better, whose names graced bicycles.
> I have Giuseppe Olmo, Cino Cinelli, Learco Guerra. Any others?
There are too many to name them all. Here is a very small sampling. All of these predate those that you mentioned:
Luigi Ganna (founded 1910), Casati (1920), Gerbi (1920's), Bottecchia (1925), Rossignoli (late 1920's), Benotto (1931), Cimatti (1932).
You should however realize that you are wrong on the account of two of the three that you already 'have'. Olmo was actually jointly founded by Giuseppe and his brothers and not by Giuseppe alone. Cinelli was actually initially founded by Cino's older brother Giotto alone and the bikes were first labelled Giotto Cinelli. Only later did Cino join in and the name then got switched to Cinelli. Giotto too was an ex-pro himself.
Giving a quick look through Lou Deeter's wonderful buyer's guide, I also came across the following: Barale brothers, Bartali, Basso, Battaglin, Bevilacqua, Chiorda, Coppi, Faggin, Fondriest, Girardengo, Guerciotti brothers, Moser, Motta, Nencini, Ottusi and Pinarello (actually founded by Nanni's uncle). Not to forget an unknown framebuilder by the name of Faliero Masi.