Hi Bruce,
I have a circa 1962 Schwinn Superior and it has a one piece bottom bracket!
I am not certain when this model was introduced. The frame is filet brazed
cromo tubing, with partial chrome rear stays and an approximate 12" band of
chrome on the seat tube. It also had a full chrome fork. Also it was 15
speeds with triple front chainrings. I picked the bike up used at a Schwinn
dealership, had it repainted by Schwinn and refurbished it mostly original,
except for wheels, rear derailleur, and saddle.
Dave Staub
Orange, Ca