Polythiophenes are an important class of materials in the field of organic electronics. The molecular structures of polythiophenes have a critical role in determining device performance; therefore, substantial efforts have been devoted to controlling their regioregularity, molecular weight and polydispersity. Herein, we demonstrate a new approach for controlling another structural parameter, the dihedral angle. We exploited the unique polymerization mechanism of cyclopolymerization: an alternating intramolecular-intermolecular chain propagation that produces a series of cyclic molecules along the polythiophene chain. We designed gemini thiophene monomers in which two thiophene monomers are tethered by an alkylene strap and we processed the monomers by using the catalyst-transfer polycondensation method. We found that the dihedral angle in the polythiophene is dictated by the size of the macrocycle formed.