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 Ferrari deciding to copy a Lada.
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, very decent, unused example of a SunTour Cap. Some of its features are:
- It is silver with the word 'SunTour' stamped into the highly chromed outer parallelogram plate.
- It has a rather cheapo pressed steel p-knuckle and a plastic spring cover.
- It has a conventional pulley cage with a highly offset guide pulley.
- The pulley cage is 60mm long, interestingly geometrical and has no Quick Cage.
I am slightly unclear about what exactly this SunTour Cap is. It seems strikingly similar to the SunTour Trimec S. All the other SunTour branded derailleurs in this series are called 'Trimec'. So why call this one 'Cap'? And what does 'Cap' mean? Is it the initials 'CAP'? If so, what do they mean? And what's with the geometrical pulley cage - a style that SunTour never used on any other model?
- 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.: 5100
- Weight: 308g including hanger plate
- Maximum cog: 34 teeth (SunTour assuming 26mm dropout)
- Total capacity: 20 teeth (SunTour assuming 26mm dropout)
- Pulley centre to centre: 60mm
- Index compatibility: friction
- Chain width: 3/32”
- Logic: top normal
- B pivot: unsprung
- P pivot: sprung
- Materials: largely steel, aluminium top knuckle
Ref. 258
