Ducati ST4S Owner's Manual page 119

Try to arrange your luggage or heavy accessories in the
lowest possible position and close to motorcycle centre.
Be sure to secure the luggage to the supports provided on
the motorcycle as firmly as possible. Improperly secured
luggage may affect stability.
Never fix bulky or heavy objects to the handlebar or to the
front mud guard as this would affect stability and cause
danger.
Do not insert any objects you may need to carry into the
gaps of the frame as these may foul moving parts. E
If you install the side panniers (available from Ducati Spare
Parts Department):
sort luggage and accessories so to distribute weight
evenly and then arrange them in the panniers so that they
are well balanced;
lock both side panniers using the suitable key lock.
Make sure the tyres are inflated to the proper pressure
indicated at page 86 and that they are in good condition.
9