  Wide binaries with hot subdwarf-B (sdB) primaries and main sequence
companions are thought to form only through stable Roche lobe overflow (RLOF)
of the sdB progenitor near the tip of the red giant branch (RGB). We present
the orbital parameters of eleven new long period composite sdB binaries based
on spectroscopic observations obtained with the UVES, FEROS and CHIRON
spectrographs. Using all wide sdB binaries with known orbital parameters, 23
systems, the observed period distribution is found to match very well with
theoretical predictions. A second result is the strong correlation between the
orbital period (P) and the mass ratio (q) in the observed wide sdB binaries. In
the P-q plane two distinct groups emerge, with the main group (18 systems)
showing a strong correlation of lower mass ratios at longer orbital periods.
The second group are systems that are thought to be formed from higher mass
progenitors. Based on theoretical models, a correlation between the initial
mass ratio at the start of RLOF and core mass of the sdB progenitor is found,
which defines a mass-ratio range at which RLOF is stable on the RGB.
