  The wave equation governing the wave propagation in chiral phononic crystals,
established through force equilibrium law, conceals the underlying physical
information. This has led to a controversy over the bandgap mechanism. In this
letter, we theoretically unveil the reason of this controversy, and put forward
an alternative approach from wave behavior to formulate the wave equation,
offering a new pathway to articulate the bandgap physics directly. We identify
the obstacles in coupled acoustic and optic branches to widen and lower the
bandgap, and introduce an approach based on spherical hinges to decrease the
barriers, for customizing the bandgap frequency and width. Finally, we validate
our proposal through numerical simulation and experimental demonstration.
