  We show that the spectral-gap of a general zero range process can be
controlled in terms of the spectral-gap of a single particle. This is in the
spirit of Aldous' famous spectral-gap conjecture for the interchange process.
Our main inequality decouples the role of the geometry (defined by the jump
matrix) from that of the kinetics (specified by the exit rates). Among other
consequences, the various spectral-gap estimates that were so far only
available on the complete graph or the $d$-dimensional torus now extend
effortlessly to arbitrary geometries. As an illustration, we determine the
exact order of magnitude of the spectral-gap of the rate-one $\textbf{ZRP}$ on
any regular graph and, more generally, for any doubly stochastic jump matrix.
