  Dipion transitions of the subthreshold bottomonium levels $\Upsilon (nS)\to
\Upsilon (n'S) \pi\pi$ with $n>n', n=2,3,4, n'=1,2$ are studied in the
framework of the chiral decay Lagrangian, derived earlier. The channels $B\bar
B, B\bar B^*+ c.c, B^* \bar B^*$ are considered in the intermediate state and
realistic wave functions of $\Upsilon (n S),B$ and $B^*$ are used in the
overlap matrix elements. Imposing the Adler zero requirement on the transition
matrix element, one obtains 2d and 1d dipion spectra in reasonable agreement
with experiment.
