From Bicycling Magazine,
"First sold in 1960, the Schwinn Varsity was the most widely sold derailleur-equipped bike of all time with nearly two million sold. The 21-inch aluminum suspension frame with a rigid fork has been jokingly called “the heaviest lightweight bicycle ever built.”
In terms of design, the Varsity looked like many European imports, but its low cost led to a high popularity. This also made the sport of cycling more accessible to Americans. The bike’s signature derailleur even popularized the term “ten-speed.” The Varsity was retired in 1960, but remains an American classic."