The Le Tour derailleur is a rebadged Crane which was the first of the Dura Ace rear derailleurs. It is very smooth and works great with the barcons. I'm pretty sure some of the Paramounts came with the Le Tour on them right around '74 or '75.
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2018 Breezer Greenway
2011 Raleigh International
'73 World Voyageurs -
Proud owner of all three colors made! Orange, Blue , Yellow .