SunTour AG Tech GTL

In 1981 SunTour introduced a 14 to 38 toothed five speed freewheel and called it the AG for ‘Alpine Gear’. It was designed to allow you to get stump-pullingly low gears on a ten speed set up. I think 38 teeth remains, to this day, the largest rear cog to be commercially available. To handle this monster SunTour produced a succession of ‘AG’ derailleurs, which were huge, crude, rock crushers loosely derivative of the  SunTour seven - with a scaled up, aluminium, rear knuckle from the V series, and a scaled up, steel, front knuckle from the Honor. The whole AG system was vaguely clunky - too big, too heavy, too ugly and with too large a difference between the ratios, but it had a devoted band of followers who wanted that ultimate low gear experience.

This example is the AG Tech GTL, with SunTour’s extra long, third generation, double pivot ‘Tech’ pulley cage grafted onto the AG parallelogram.

As E.F. Schumacher might have said, smaller would have been more beautiful.


  1. Brand: SunTour

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

  3. Country: Japan

  4. Date of introduction: 1985?

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

  6. Model no: 5600

  7. Weight: 344g

  8. Maximum cog: 38 teeth (Source: Sutherlands 4th edition)

  9. Total capacity: 38 teeth (Source: Sutherlands 4th edition)

  10. Pulley centre to centre: 80mm

  11. Index compatibility: friction

  12. Chain width: 3/32”

  13. Logic: top normal

  14. Pivots: two pivots, front sprung and rear unsprung

  15. Material: largely steel with an aluminium rear knuckle and link plate