SunTour XC (3 Pulley System)

SunTour XC derailleur (3 pulley system) main image

SunTour’s first mountain bike design, the MounTech had been a masterpiece of technical complexity and sophistication - disastrously let down by reliability problems. The SunTour XC was the second design. The basic SunTour XC was a rock-crusher of a derailleur, over-size and over-built in every area. It was as simple as a knife and fork, with one sprung pivot and no fancy features, even the styling and branding were deliberately plain and straight forward.

So what in heaven’s name is this? SunTour were wrestling with the demands of the new mountain bikes, with their triple chainsets and huge gear capacities. They hated the very long pulley cages, which had limited ground clearance and irritating chain slap - so they invented the ‘3 Pulley System’. With one brilliant stroke it gave huge capacity with a relatively short cage. Ground clearance was restored, chain slap minimised.

Fantastic - except for the fact that it looked so weird that, as you cycled by, dogs barked, babies cried and your friends laughed. At you, not with you.

Sales were lamentably slow.

  • Derailleur brands: SunTour
  • Categories: SunTour - the mountain bike gears
  • Country: Japan
  • Date of introduction: 1985
  • Date of this example: 1986 (two letter date code is CE)
  • Model no.: unknown
  • Weight: 260g
  • Maximum cog: 34 teeth?
  • Total capacity: 38 teeth?
  • Pulley centre to centre: 56.5mm
  • Index compatibility: friction
  • Chain width: 3/32”
  • Logic: top normal
  • B pivot: unsprung
  • P pivot: sprung
  • Materials: largely aluminium, with a steel inner pulley cage plate
SunTour XC derailleur (3 pulley system) additional image 01

Browse associated documents.