PS was a brand of motorcycle which Francesco Vincenzo Lanfranchi produced in his workshop in Via De Filippi in Milan.
Marchio con cui Francesco Vincenzo Lanfranchi produce biciclettte a motore nella sua officina di via De Filippi a Milano (vedi F.V.L.).
Lanfrachi of Florence was a fine rider famed for setting world speed records in France with Peugeot in the early 1900s.
Further information: F.V.L.
Source: Moto di Lombardia
N.B. No other source mentions the PS marque.
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