For 1990 the Euclid derailleur gained a cable adjuster and a smooth allen key cable clamp bolt. This is a rather pleasant medium cage example, although it still weighs a chunky 300g.

One unusual feature is that it sports Campagnolo's full ball-bearing pulley wheels in white. I am not entirely sure that these are original, although I have seen a number of other Euclids of various sorts with these pulleys.

Some relevant details are:

• There is a spring adjuster on the p-pivot.
• The cable adjuster is round and threads straight into the aluminium of the b-pivot.
• It has a single parallelogram spring using ~2.0mm wire.
• The inner parallelogram plate is an aluminium forging (making this a Euclid rather than a Centaur !?).
• The cable clamp nut is a smooth Allen key item.
• The pulley wheels are full ball-bearing items in white.
• The inner pulley cage plate is steel and has a spoke deflector.

• Derailleur brands: Campagnolo
• Categories: Campagnolo - mountain bike madness
• Country: Italy
• Date of introduction: 1990?
• Date of this example: unknown
• Model no.: M010-MD
• Weight: 300g
• Maximum cog: 34 teeth (Campagnolo)
• Total capacity: 38 teeth (Campagnolo)
• Pulley centre to centre: 69mm
• Index compatibility: 8 speed
• Chain width: 3/32
• Logic: top normal
• B pivot: sprung
• P pivot: sprung
• Materials: aluminium with a steel inner pulley cage