This series of derailleurs caused me distress and dismay when it appeared. SunTour seemed to have abandoned the best design in the world (the slant parallelogram) and copied the geometry of the much despised 1976 Huret Eco, which was, in turn, the bastard child of the 1963 Huret Svelto.
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).
Despite these touches SunTour’s decision to adopt this basic geometry was like director of ‘ER’ deciding steal the script of ‘Holby City’
SunTour produced a surprisingly wide range of derailleurs using this unpromising main parallelogram, including:
- Versions using a conventional pulley cage, albeit with a guide pulley that was dramatically off-set from the lower pivot. This was an attempt to get the Huret geometry to provide a decent change over a wide-ish freewheel.
- Versions using a three pivot 'Tech' design - in partial imitation of the Huret Duopar.
- Versions braqnded up for Bridgestone that incorporated an in-derailleur indexing system. These were part of ther Bridgestone Klimatic series.
This is a, slightly corroded, example of a Trimec (4600). Some of its features are:
- It has black knuckles with the word 'SunTour' stamped into the highly chromed outer parallelogram plate.
- It has an aluminium p-knuckle.
- It has a triple pivot design with a double pivot pulley cage.
- The pulley cage is 61mm long and has a Quick Cage.
- Derailleur brands: SunTour
- Categories: SunTour - Frank Berto and the curse of Duopar
- Country: Japan
- Date of introduction: 1982?
- Date of this example: 1982 (two letter date code is YG)
- Model no.: 4600
- Weight: 305g
- Maximum cog: 26 teeth (hanger 27mm or less) or 28 teeth (hanger 29mm) (Source: SunTour)
- Total capacity: 28 teeth (Source: SunTour)
- Pulley centre to centre: 61mm
- Index compatibility: friction
- Chain width: 3/32”
- Logic: top normal
- B pivot: unsprung
- P pivot: two, both sprung
- Materials: largely steel with aluminium knuckles
Ref. 47
