Stambēlī is a trance healing music developed over centuries by displaced sub-Saharans in Tunisia. It features a monophonic, deeply cyclic, and subtly transformative rhythmic system designed for entrainment. This rhythmic system is characterized by 1) a metric framework of non-isochronous beat patterns and 2) a gradual and normative rhythmic cycle compression that gradually transforms the non-isochronous beat subdivisions into nearly isochronous ones as the tempo increases. In this article, I illustrate these transformations through chronometric analysis of songs in each of stambeli’s four rhythms. I propose a set of musical and ritual conditions that contribute to this rhythmic elasticity, and suggest that close analytical attention to Stambēlī’s rhythmic system broadens our understanding of “African” rhythm and meter.