  We improve Larman's bound on the diameter of a polytope by showing that if
$\Delta$ is a normal simplicial complex, all of whose missing faces have size
at most $r$, then the diameter of the facet-ridge graph of $\Delta$ is not
larger than $2^{r-2}n$, where $n$ is the number of vertices of $\Delta$. We
then use this result to provide new upper bounds on the diameters of the
facet-ridge graphs of $k$-neighborly spheres, $r$-stacked spheres, and
polytopes with small $g_r$. Specifically, our bounds imply that $r$-stacked
spheres with $r=O(\log n)$ satisfy the polynomial Hirsch conjecture.
