I believe, like many C&V members, the Centurion Ironman makes for a fine road bike.
The only thing "triathlon" about it is marketing (Dave Scott and Ironman) because it essentially has classic road bike frame geometry.
However, it was around that same time period (1988/89) that Quintana Roo ushered in the design of bike frames with steeper seat tube angles meant to be ridden with aero bars.
They also pioneered 650C wheels with these frames for most sizes.
This configuration (steep seat tube angles 76-80 degrees, aerobars,) quickly became the norm for triathletes of the 1990s and became somewhat standard for tri-bike frame geometry.
Centurion Ironman was never a part of this.
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WTB: Slingshot bicycle promotional documents (catalog, pamphlets, etc).
WTB: American Cycling May - Aug, Oct, Dec 1966.
WTB: Bicycle Guide issues 1984 (any); Jun 1987; Jul, Nov/Dec 1992; Apr 1994; 1996 -1998 (any)
WTB: Bike World issue Jun 1974.