BMW Motorrad S 1000RR 2013, Rider'S Manual

Page: 113 / 200

Do not attempt a burn-out
unless the ABS function is
switched OFF.
How does ABS work?
The amount of braking force that
can be transferred to the road
depends on factors hat include
the coefficient of friction of the
road surface. Loose stones, ice
and snow or a wet road all have
much lower coefficients of friction
than a clean, dry asphalt surface.
The lower the coefficient of fric-
tion, the longer the braking dis-
tance.
If the rider increases braking
pressure to the extent that brak-
ing force exceeds the maximum
transferrable limit, the wheels
start to lock and the motorcycle
loses its directional stability; a fall
is imminent. Before this situation
can occur, ABS intervenes and
adapts braking pressure to the
maximum transferrable braking
force, so the wheels continue
to turn and directional stability
is maintained irrespective of the
condition of the road surface.
What are the effects of
surface irregularities?
Humps and surface irregular-
ities can cause the wheels to
lose contact temporarily with the
road surface; if this happens the
braking force that can be trans-
mitted to the road can drop to
zero. If the brakes are applied
under these circumstances, the
ABS has to reduce braking force
to ensure that directional sta-
bility is maintained when the
wheels regain contact with the
road surface. At this instant the
BMW Motorrad Integral ABS
must assume an extremely low
coefficient of friction, so that the
wheels will continue to rotate un-
der all imaginable circumstances,
because this is the precondition
for ensuring directional stability.
As soon as is registers the ac-
tual circumstances, the system
reacts instantly and adjusts brak-
ing force accordingly to achieve
optimum braking.
What feedback does the
rider receive from the
BMW Motorrad Race
ABS?
If the ABS system has to reduce
braking force on account of the
circumstances described above,
vibration is perceptible through
the brake lever.
When the brake lever is pulled,
brake pressure is also built up
at the rear wheel by the integral
function. If the brake pedal is
depressed after the brake lever
is pulled, the brake pressure built
up beforehand is perceptible as
counter-pressure sooner than is
the case when the brake pedal is
depressed either before or at the
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z Engineering details