In the late 1980s and early 1990s Campagnolo produced a bewildering array of derailleurs that all looked extremely similar. This poses the perfect puzzle for derailleur geeks who can endlessly debate exactly which is what.

I think that this well-used derailleur is an early example of a Campagnolo Chorus (RD01-CH). I guess that it is a Chorus (RD01-CH) because it has no ball bearings in its pulley wheels, an Allen key cable clamp bolt and no spring adjuster on the p-pivot. I speculate that it is an early version because the inner pulley cage plate is a casting rather than a pressing. There is probably someone out there who knows for sure - if that someone is you, please let me know!

A list of relevant details might include:

• There is no spring adjuster on the p-pivot.
• The cable adjuster is round and threads straight into the aluminium of the b-pivot.
• It has a double parallelogram spring using ~1.5mm wire.
• The inner parallelogram plate is a stippled aluminium pressing.
• The cable clamp nut is a Allen nut.
• The pulley wheels are Campagnolo's typical plain bearing design, in black.
• The inner pulley cage plate is a polished aluminium casting and has no spoke deflector.

• Derailleur brands: Campagnolo
• Categories: Campagnolo - the locust years
• Country: Italy
• Date of introduction: early 1992?
• Date of this example: unknown
• Model no.: RD01-CH
• Weight: 246g
• Maximum cog: 26 teeth (Sutherlands 6th edition)
• Total capacity: 26 teeth (Sutherlands 6th edition)
• Pulley centre to centre: 46mm
• Index compatibility: 8 speed
• Chain width: 3/32
• Logic: top normal
• B pivot: sprung
• P pivot: sprung
• Materials: aluminium