This paper theoretically studies thermoreversible gelation driven by aggregation of helices formed on the polymer chains. Two fundamentally different cases of W multiple association of single helices, and (ii) association by multiple helices with multiplicity k (such as double helices (k = 2), triple helices (k = 3), etc.) are treated on the basis of different equations. The helix length distribution on a polymer chain (or assemble of chains for multiple helices) is derived as a function of polymer concentration and temperature. It obeys a power law of the parameter t = 1 - v/(1 - theta), where theta is the helix content per chain and v is the average number of helices on a chain divided by the total number n of the repeat units. The sol/gel transition point is found on the temperature-concentration plane. It is found that, in the case of k-ple helices, the condition ntheta/(ζ) over bar = k/(k - 1) is fulfilled at the gel point, where (ζ) over bar is the average helix length. Hence, the independent measurement of theta and (ζ) over bar gives the multiplicity k. Theoretical calculation of the total helix content in the solution is compared with experimental data of optical rotation in i-carrageenan solutions at different polymer concentrations. It is shown that at low temperature there is a sharp transition from network to bundle state (pair, triplet, etc.). This network-to-bundle transition becomes a real phase transition in the limit of infinite chain length.