There’s something about French touring derailleurs after about 1960. Just one look at this Simplex SX610 GT is enough to make me feel utterly exhausted and dispirited. I can almost hear the chain hysterically clattering on the inaccurately cut teeth of the wide ratio Maillard freewheel as the SX610 GT pathetically attempts to find bottom gear. I can almost see the bemused expression on the face of the owner of a Peugeot tandem as I attempt to invent a reason why a seemingly rational company like Peugeot had chosen to fit his relatively demanding machine with a poorly constructed derailleur with a plastic inner parallelogram plate.

The basic idea for the Simplex SX610 GT was unoriginal but acceptable - Simplex thought they would just copy a mid range Shimano touring derailleur. The execution was terrible - it weighed a ton (tonne?), it looked dreadful, the springs lasted about 23 milliseconds, it had Simplex’s tedious hanger bolt system and it simply never quite worked right.

It’s enough to make you down a bottle of Absinthe in a single gulp and run off to join the Foreign Legion.

• Derailleur brands: Simplex
• Categories: Simplex - touring terrors
• Country: France
• Date of introduction: 1982?
• Date of this example: unknown
• Model no.: SX610 GT
• Weight: 308g
• Maximum cog: 34 teeth (Simplex) or 36 teeth (Sutherland’s 6th edition)
• Total capacity: 38 teeth (Sutherland’s 6th edition)
• Pulley centre to centre: 75mm
• Index compatibility: friction
• Chain width: 3/32”
• Logic: top normal
• B pivot: sprung
• P pivot: sprung
• Materials: plastic parallelogram plates, steel pulley cage plates and parallelogram stiffening plates, aluminium knuckles