  Flops are birational transformations which, conjecturally, induce derived
equivalences. In many cases an equivalence can be produced as pull-push via a
resolution of the birational transformation; when this happens, we have a
non-trivial autoequivalence of either sides of the flop known as the
\emph{flop-flop autoequivalence}. We prove that such autoequivalence can be
realised as the inverse of a spherical twist around a conservative, spherical
functor in a natural way. More precisely, we prove that a natural, conservative
spherical functor exists in a more general framework and that the flop-flop
autoequivalence fits into this picture. We also give an explicit description of
the source category of the spherical functor for standard flops (local model
and family case) and Mukai flops. We conclude with some speculation about
Grassmannian flops and the Abuaf flop.
