Waterford worked closely with True Temper to develop oversized tubing for road bikes in 1988, and one of the features of that and subsequent OS tubesets was the seat tube conical flare at the bottom bracket to provide additional lateral stiffness. The True Temper OS tubeset was introduced as an option on production Paramounts in 1989 and was called "Paramount with Paramount Tubing" in the 1989 catalog (Schwinn offered the Paramount in both the True Temper OS version and the standard tubing version using Columbus SLX in smaller frames and a mix of SL and SP in larger frames in 1989 and 1990).

I know Ben pioneered oval cross section tubing, but when did he start using seat tubes that flared at the BB shell?