This gear caused me distress and dismay when it appeared. SunTour seemed to have abandoned the best design in the world (the slant parallelogram) and faithfully copied the 1975 Huret Duopar, a derailleur that I personally detested for its fragility and dishonesty - it promised so much and delivered so little.

The design did have some interesting details. SunTour had adopted a ‘Light Action’ style sprung cable clamp (in imitation of one of Shimano’s better features). They had also used their infamous guide-pulley-with-an-internal -spring design. True to form this example, which is otherwise completely workable, has a totally destroyed guide pulley.

Despite these details, SunTour’s decision to adopt this geometry was like the director of ‘ER’ deciding steal the script of ‘Holby City’.


  1. Brand: SunTour

  2. My category: SunTour - Frank Berto and the curse of Duopar

  3. Country: Japan

  4. Date of introduction: 1982?

  5. Date of this example: 1982 (two letter date code is YG)

  6. Model no: 4600

  7. Weight: 305g

  8. Maximum cog: 26 teeth (hanger 27mm or less) or 28 teeth (hanger 29mm) (Source: SunTour)

  9. Total capacity: 28 teeth (Source: SunTour)

  10. Pulley centre to centre: 61mm

  11. Index compatibility: friction

  12. Chain width: 3/32”

  13. Logic: top normal

  14. Pivots: three pivots, the rear unsprung, the other two sprung

  15. Material: largely steel with aluminium knuckles


SunTour Trimec black (4600)