The Schwinn GT510 was supposedly an improvement on the insane Schwinn GT500.

The Allen key hanger bolt has been replaced by a riveted on hanger, with a dodgy hidden plastic insert playing a key structural role between the hanger and the body of the derailleur - probably not good. You get a funky black drop out bolt and adjustable cable outer stop. Weirdest of all you seem to get one of Huret’s toothless ball bearing mounted tension pulleys - very hip in 1960.

What anyone in France or Chicago can have been thinking about speccing this gear in 1978 is beyond comprehension.

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• Derailleur brands: Schwinn, manufactured by Huret
• Country: USA, manufactured in France
• Date of introduction: 1977?
• Date of this example: 1978 (stamped 3778, week 37 1978)
• Model no.: unknown
• Weight: 345g including hanger plate
• Maximum cog: 28 teeth (Sutherland’s 4th edition)
• Total capacity: 30 teeth (Sutherland’s 4th edition)
• Pulley centre to centre: 50mm
• Index compatibility: friction
• Chain width: 3/32”
• Logic: top normal
• B pivot: unsprung
• P pivot: sprung
• Materials: largely steel with one bronze parallelogram arm