3ttt superleggero bar intro:
Not an exact date, but the shop for which I later worked had them prior to April 1974, in a Merckx bend, up to 42 cm. I considered them as I had regular 3ttt Grand Prix bars, but the price $18.50 was too steep. Spent $15.00 on a used set of Record pedals instead, from a worker moving up to Suppleggeri units.
They did not get them from a typical USA distributor, came from Andre Bertin.
Regarding Campagnolo brake lever clamps, overtightening would cause the bar band to stretch. If this was found, one work around was to install the whole clamp after taping bars, exposing the clamp behind the hood. Never saw that style on Cinelli bars, but often on 3ttt.
John Jorgensen
Torrance Ca