This is another fascinating derailleur. It is a fairly faithful copy of the famously crude and ugly 1980s Simplex SX1 (or Alpha) - but with its own quixotic flourishes. Dig those glossy pulley cage plates.

It has 'SPARK' carved into its outer parallelogram plate in a touchingly simple but accurate way, and also has 'SPARK' cast onto its p-knuckle. From this I cunningly deduce that it is manufactured by Spark Engineering of Ghaziabad, India.

I bought it from a person in the Czech Republic. How it made its way from the fragrant suburbs of New Delhi to the stag party capital of Central Europe remains a mystery to me.

• Derailleur brands: Spark
• Country: India
• Date of introduction: 1995?
• Date of this example: unknown
• Model no.: unknown
• Weight: 252g
• Maximum cog: 28 teeth (based on Simplex SX1/Alpha)
• Total capacity: 30 teeth (based on Simplex SX1/Alpha)
• Pulley centre to centre: 54mm
• Index compatibility: friction
• Chain width: 3/32”
• Logic: top normal
• B pivot: unsprung
• P pivot: sprung
• Materials: steel with plastic knuckles