Schwinn GT120

Schwinn GT120 derailleur main image

After the horror of being forced to imitate a Huret Allvit with the Schwinn GT100, Schwinn allowed Shimano a bit more freedom with the design of the Schwinn GT120. The GT120 is basically a Shimano Lark STO with Schwinn touches:

  • A huge bashguard built onto the rear knuckle.
  • An allen key hanger bolt - of no known purpose - it is not a 10mm thread.
  • A larger cable adjuster.
  • A trapped cable clamp bolt - of rather nasty Huret-like design.

Shimano did take the opportunity to build-in their latest adjustment screw layout - with plastic shake proofing instead of steel springs.

This example has two sets of date code letters stamped on it (AC and YL) - holding out the promise that it is the Rosetta Stone of the two Shimano year letter systems - but it still does not quite make sense. I think A is 1976 in the ‘new’ system, Y is 1979 in the ‘old’ system. I have gone with 1976.

One day it will all become clear.

  • Derailleur brands: Schwinn, manufactured by Shimano
  • Country: USA, manufactured in Japan
  • Date of introduction: 1974
  • Date of this example: 1976 (date codes are AC and YL!, ‘elliptical S’ marking on pulleys)
  • Model no.: unknown
  • Weight: 366g including hanger plate but excluding drop-out bolt
  • Maximum cog: 28 teeth
  • Total capacity: 28 teeth
  • Pulley centre to centre: 54mm
  • Index compatibility: friction
  • Chain width: 3/32”
  • Logic: top normal
  • B pivot: sprung
  • P pivot: sprung
  • Materials: steel