Experimental evidence is presented in support of a simple model, containing one adjustable parameter, which accounts for the dependence of the limiting frequency of single bubble propagation on bias field, rotating field intensity, and circuit period. The parameter, which characterizes the design of the overlay, is defined as the magnetic pole strength per unit of in‐plane field. Having the dimensions of area, it is referred to as the cross section &sgr;. Data taken on the same circuit designs at different periods (&lgr;) confirm the expectation that &sgr; is proportional to &lgr;2. We found &sgr;/&lgr;2=0.016 for T‐X circuits, 0.014 for T‐Bar circuits, and 0.012 for a 3‐bar chevron design.