This is an interesting, but thoroughly distressed, remnant of a derailleur. Clearly, it was once a copy of a 1950s Simplex Tour de France, and quite a decently engineered copy at that.

The main arm appears to have no branding on it (unlike a basic Simplex). There are also no rivet holes in the main arm to which a brass or enamelled nameplate could be attached (unlike a posher Simplex). The interest comes from the words embossed on the pulley cage. The outer plate reads "Zotta, mar. reg., Industria Argentina". I would translate this as "Zotta, Registered Trademark, Made in Argentina". The inner plate reads "5 Vel, Cat 3/32", which I would translate as "5 Speed, Chain 3/32".

The only Argentinian person who was willing to express an opinion, suggested that this derailleur dated from a period from the late 1950s to the early 1960s. You might well have guessed that yourself.

• Derailleur brands: Zotta
• Country: Argentina
• Date of introduction: 1959?
• Date of this example: unknown
• Model no.: unknown
• Weight: not complete enough to be useful
• Maximum cog: 26 teeth?
• Total capacity: 15 teeth?
• Pulley centre to centre: 43mm
• Index compatibility: friction
• Chain width: 3/32”
• Logic: low normal
• B pivot: sprung
• P pivot: sprung
• Materials: steel with an aluminium spring tension adjuster ring