If the Shimano Positron AX was the coming together of Shimano’s disastrous Positron technology with its much sneered at AX aerodynamic design. Then this derailleur was SunTour’s riposte - the coming together of its widely ignored in-derailleur indexing technology, its derided Trimec design and its hopelessly unreliable ‘Tech’ three pivot technology.

And just like the Positron AX, the result of this marriage of monstrosities was a surprisingly solid and workable derailleur. Albeit one that nobody wanted to buy.

I believe that SunTour manufactured the Klimatic range exclusively for Bridgestone - the lucky devils.


  1. Brand: Bridgestone, manufactured by SunTour

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

  3. Country: Japan

  4. Date of introduction: 1982?

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

  6. Model no: unknown

  7. Weight: 389g

  8. Maximum cog: 28 teeth?

  9. Total capacity: 28 teeth?

  10. Pulley centre to centre: 57mm

  11. Index compatibility: 5 speed?

  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


Bridgestone Klimatic (1st style)