  We experimentally and theoretically study the dynamics of a one-dimensional
array of pendula with a mild spatial gradient in their self-frequency and where
neighboring pendula are connected with weak and alternating coupling. We map
their dynamics to the topological Su-Schrieffer-Heeger (SSH) model of charged
quantum particles on a lattice with alternating hopping rates in an external
electric field. By directly tracking the dynamics of a wavepacket in the bulk
of the lattice, we observe Bloch oscillations, Landau-Zener transitions, and
coupling between the isospin (i.e. the inner wave function distribution within
the unit cell) and the spatial degrees of freedom (the distribution between
unit cells). We then use Bloch oscillations in the bulk to directly measure the
non-trivial global topological phase winding and local geometric phase of the
band. We measure an overall evolution of 3.1 $\pm$ 0.2 radians for the
geometrical phase during the Bloch period, consistent with the expected Zak
phase of $\pi$. Our results demonstrate the power of classical analogs of
quantum models to directly observe the topological properties of the band
structure, and sheds light on the similarities and the differences between
quantum and classical topological effects.
