Engineering Details; Brake System With Bmw Motorrad Abs - BMW F700 gs Rider's Manual

Brake system with
BMW Motorrad ABS
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 hap-
pens the braking force that can
be transmitted to the road can
drop to zero. If the brakes are
applied under these circum-
stances the ABS has to reduce
braking force to ensure that dir-
ectional stability is maintained
when the wheels regain contact
with the road surface. At this in-
stant the BMW Motorrad 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.
Rear wheel lift
Under very severe and sudden
deceleration, however, under
certain circumstances it is pos-
sible that the BMW Motorrad
ABS will be unable to prevent
the rear wheel from lifting clear
of the ground. If this happens
the outcome can be a highsiding
situation in which the motorcycle
can flip over.
Severe braking can cause
the rear wheel to lift off the
ground.
When you brake, bear in mind
that ABS control cannot always
be relied on to prevent the rear
wheel from lifting clear of the
ground.
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