The SunTour SX-100 is the SunTour S-1 redesigned so that it fits to a drop-out and does not need any special fittings on the chainstay. The SX-100 also has the indexing in the lever (usually a twist grip), not in the derailleur. The pulley cage is very short, as this gear is aimed at commuter and utility bikes with a single chainwheel.

It retains the somewhat elegant the horizontal parallelogram, but the mounting has become gross. This example has a Japanese-style ‘hanger’ with a rear facing slot.

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• Derailleur brands: SunTour, manufactured by SR SUNTOUR
• Categories: SunTour - indexing insanity
• Themes: Small wheels on my wagon
• Country: Japan
• Date of introduction: 1993
• Date of this example: 1994 (two letter date code is KA)
• Model no.: SX-100
• Weight: 362g including hanger plate
• Maximum cog: 28 teeth?
• Total capacity: 26 teeth?
• Pulley centre to centre: 43mm
• Index compatibility: 5 speed?
• Chain width: 3/32”
• Logic: top normal
• B pivot: none
• P pivot: sprung
• Materials: largely steel, with a plastic rear knuckle and inner pulley cage plate