  We analyze the transition temperature $T_c$ of bipolaronic superconductivity
in a bond Su-Schrieffer-Heeger (bond-SSH) model -- also known as a bond Peierls
model -- where the electron hoppings are modulated by bond phonons. Using a
semiclassical instanton approximation justifiable in the adiabatic limit of
slow phonons, we find that the bipolaron mass is only weakly enhanced, in
contrast to the typical large mass enhancement found in standard (Holstein)
electron-phonon models. Specifically, in the strong coupling limit, the
bipolarons can freely slide within a degenerate manifold rather than become
self-trapped. A gas of these bipolarons can undergo a superfluid transition at
a critical temperature for which we obtain an upper bound. We find that this
bound is exponentially larger than that in the Holstein model. Our study
provides an analytical understanding of the mechanism behind the high-$T_c$
bipolaronic superconductivity numerically observed in [Phys. Rev. X 13, 011010
(2023)].
