Rod-like molecules combining a fork-like triple chain end and a cycloaliphatic apex are introduced as a new design concept for materials with broad ranges of bicontinuous cubic (Cub_bi) phases. By ring expansion from n = 4 to 12 a sequence of three Cub_bi phases is observed; the achiral double gyroid lad phase, a chiral “Im3m” phase and an achiral re-entrant lad phase. The chiral “Im3m” phase is formed if the helical twist between the molecules along the networks is in the range of 8.6°–9.5°, either for the individual compounds or their mixtures.