In the pantheon of Shimano’s aero derailleurs, the Shimano Adamas AX dwells in that no-man’s-land between prestige and utility - the very no-man’s-land where profits should be maximised. It has just enough aluminium and shiny Allen bolts to catch the beady eye of the eager punter, and just enough pressed steel to put a smile on the face of each and every one of Shimano’s shareholders. What a pity it didn’t sell.

The parallelogram, front knuckle and pulley cage look very like those of the budget Shimano Positron AX, the rear knuckle is a nod towards the enthusiast’s Shimano 600 AX. That grey plastic ‘aerodynamic’ cover over the hole for the adjustment screw is just the kind of ‘value added’ feature that drives mechanics nuts (and thereby provides an invaluable service to humanity).

The person, from whom I acquired this derailleur, insisted on referring to it as a ‘Shimano XO sewepe’. This had me totally confused until I realised that he was reading the name upside-down. In his defence I have to acknowledge that ‘XO sewepe’ is exactly as meaningful as ‘adamas AX’. Adamo, adamas, adamat, adamamus, adamatis, Adam Ant - stand and deliver - your money or your life... who can forget 1981?

• Derailleur brands: Shimano
• Categories: Shimano - Positron indexing insanity, Shimano - the turbulent AX story
• Country: Japan
• Date of introduction: 1981
• Date of this example: 1981 (two letter date code FG)
• Model no.: AD10
• Weight: 273g
• Maximum cog: 28 teeth (Shimano)
• Total capacity: 28 teeth (Shimano)
• Pulley centre to centre: 58mm
• Index compatibility: 6 speed
• Chain width: 3/32”
• Logic: top normal
• B pivot: unsprung
• P pivot: sprung
• Materials: largely steel, with an aluminium rear knuckle