Expandable band systems for wearable devices, such as spatial computing headsets, are provided which have flexible and conformable form factors that enable users to reliably to secure such wearable devices in place. Further, in the context of spatial computing headsets with an optics assembly supported by opposing temple arms, the expandable band systems provide protection against over-extension of the temple arms or extreme deflections that may otherwise arise from undesirable torsional loading of the temple arms.