Ducati SPORTTOURING ST4s 2005 Manuel D'utilisation Et Entretien page 170

ABS uses hydraulics and electronics to limit pressure in
the brake circuit when a special sensor mounted to the
wheel signals the electronic control unit that the wheel is
about to lock up.
This avoids wheel lockup and preserves traction. Pressure
is raised back up immediately and the control unit keeps
controlling the brake until the risk of a lockup disappears.
Normally, the rider will perceive ABS operation as a harder
feel or a pulsation of the brake lever and pedal.
E The front and rear brakes use separate control systems,
meaning that they operate independently. Likewise, the
ABS is not an integral braking system and does not control
both the front and rear brake at the same time.
The ABS may be turned off by pressing the button
incorporated in the LH switch (see page 31).
60
Warning
When the ABS is off, the vehicle provides the
standard braking force offered by the regular braking
system. As a result, using one brake at a time will reduce
braking efficiency. Never use brake controls harshly or
violently or you may lock the wheels and lose control of
the motorcycle. When riding in the rain or on slippery
surfaces, braking will become less effective. Always use
the brakes very gently and carefully when riding under
these conditions. Any sudden manoeuvres may lead to
loss of control. When tackling long, high-gradient downhill
road tracts, shift down gears to use engine braking. Apply
one brake at a time and use brakes sparingly. Keeping the
brakes applied all the time would cause the friction
material to overheat and reduce braking power
dangerously. Underinflated tyres reduce braking
efficiency, handling accuracy and stability in a bend.