Gaseous carbon begins to aggregate in the form of linear chains and rings. While chains have consistently been observed in a variety of conditions that led to their spectroscopic characterization, rings remain elusive, a fact that seemingly conflicts with their well-known higher stability (from 10 atoms onwards). The increase in temperature favors thermodynamically the chain population. Calculations, for C-8, C-10, and C-12, of the temperature-dependent rate constants for chain-ring and ring-chain interconversion from ab initio B3LYP/6-311G* data shows that from similar to 1000 K, that is, at temperatures just below the lower end of those used in the clusters production, the conversion is rapid in the experimental time-scale both in the singlet and the triplet multiplicities.