The SunTour Vx S badged up for Fuji.

The ‘x’ in Vx was widely understood as standing for ‘extra light’ (I do not know whether this was SunTour’s real intention). This was the SunTour V after it had been on a strenuous diet, the pulley cage plates were aluminium, the steel holder for the cable clamp bolt has been replaced by an aluminium channel and the knuckles are slimmer and neater.

Despite the weight loss, this was an extremely affordable, strong and reliable derailleur - I still see many Vx’s in use on the roads today.

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• Derailleur brands: Fuji (manufactured by SunTour)
• Country: Japan
• Date of introduction: 1978?
• Date of this example: 1980 (two letter date code is WG)
• Model no.: RD-2500?
• Weight: 212g
• Maximum cog: 28 teeth
• Total capacity: 26 teeth
• Pulley centre to centre: 59mm
• Index compatibility: friction
• Chain width: 3/32”
• Logic: top normal
• B pivot: unsprung
• P pivot: sprung
• Materials: aluminium