SunTour Scrambler (1st style)

SunTour Scrambler derailleur main image

With the Scrambler, SunTour introduced yet another mid-end indexing mechanism. This is a system based on an indexed lever, with the rear derailleur merely centred with a single adjusting screw, and with a ‘Light Action’ type spring built into the cable clamp mount. It is possibly the fourth indexing system Suntour introduced within a decade - not a good idea.

Heavy, ugly and not particularly cheap, no one was very interested.

But three features catch my eye:

  • The pulley cage plates have a ninja/sci-fi look.
  • It has an unusually large, 12 tooth, guide pulley.
  • The centre of the guide pulley is offset from the p-pivot by a tiny amount - echoing a geometry that SRAM would later use on their ESP designs.

I think that this particular example is a early version with the following traits:

  • The knuckles are grey.
  • The main Allen bolts are chrome.
  • The writing on the outer parallelogram plate is black on silver.
  • The pulley wheels are black.

  • Derailleur brands: SunTour
  • Categories: SunTour - indexing insanity
  • Country: Japan
  • Date of introduction: 1985?
  • Date of this example: 1985 (two letter date code is BH)
  • Model no.: SR21
  • Weight: 328g
  • Maximum cog: 32 teeth?
  • Total capacity: 34 teeth?
  • Pulley centre to centre: 65mm
  • Index compatibility: 5 speed?
  • Chain width: 3/32”
  • Logic: top normal
  • B pivot: unsprung
  • P pivot: sprung
  • Materials: aluminium knuckles, steel parallelogram plates and pulley cage plates