With the Shimano RS (RS12) the already venerable Skylark design took a couple of small steps forward. The cable clamp was mounted on a Centeron lever, allowing the derailleur to automatically compensate for the need to overshift. Perhaps more significantly the Centeron lever acted on the outer parallelogram plate - changing the geometry of the gear, as previously the cable clamp was attached to the front knuckle.

Despite these changes, the RS is a cheap, basic, tidy, design that is clearly a Shimano Skylark underneath.

• Derailleur brands: Shimano
• Categories: Shimano - from Skylark to world domination
• Country: Japan
• Date of introduction: 1981?
• Date of this example: 1981 (two letter code FB)
• Model no.: RS12
• Weight: 290g including hanger plate
• Maximum cog: 28 teeth
• Total capacity: 28 teeth
• Pulley centre to centre: 54mm
• Index compatibility: friction
• Chain width: 3/32”
• Logic: top normal
• B pivot: sprung
• P pivot: sprung
• Materials: steel

Ref. 196