Using the 4-cyanobiphenyl mesogenic core unit, in this work we have studied different combinations of ring size, alkyl chain length and linking-unit and their impact on the mesomorphic behaviour of the resulting materials. In all cases the cyclic group was directly attached to the alkyl chain and can be described as non-polar; we can therefore attribute any changes in behaviour solely to steric factors. Some cyclic terminal groups were found to give significant enhancements to the transition temperatures relative to the linear unsubstituted parent compounds, to induce smectic phases for relatively short terminal chain lengths, as well as leading to anomalously large smectic layer spacings and strong odd-even effects.