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 interested - but the Scrambler’s pulley cage plates have an interesting ninja/sci-fi look and it has an unusual 12 tooth guide pulley.


  1. Brand: SunTour

  2. My category: SunTour  - indexing insanity

  3. Country: Japan

  4. Date of introduction: 1985?

  5. Date of this example: 1985 (two letter date code is BH)

  6. Model no: SR21

  7. Weight: 328g

  8. Maximum cog: 32 teeth?

  9. Total capacity: 34 teeth?

  10. Pulley centre to centre: 65mm

  11. Index compatibility: 5 speed?

  12. Chain width: 3/32”

  13. Material: aluminium knuckles, steel parallelogram plates and pulley cage plates


SunTour Scrambler