There is not a lot of information about the Circuit Racer model in the IRD literature.  The catalog makes it sound like a pure custom bike which was likely made in relatively small numbers.  Bottom bracket is at a relatively normal 12.25" and the top tube is 24" on a 17" frame.  IRD parts include Switchback brakes, seat post and aluminum-legged Expedition fork.  If we can find an IRD stem and IRD keeper kit for the Bullseye cranks, we'll add those to the bike.  One interesting feature is the roller for teh rear brake to redirect the down tube routed rear brake cable.