Asymmetric price cycles similar to Edgeworth Cycles are appearing in increasingly many retail gasoline markets in the United States and worldwide. The asymmetry in the cycles can give rise to a finding of asymmetric price responses to cost shocks (asymmetric passthrough). This article estimates asymmetric passthrough for the market of Toronto, which exhibits cycles, and decomposes it into two components - that part explainable by the cycles and that part driven by other unknown sources. Significant asymmetric passthrough is found, with increases passed through more quickly than decreases. A significant cause of the finding is the presence of the cycles themselves.