BMW F 800 GS Adventure Rider's Manual page 89

than a clean and dry asphalt sur-
face. The lower the coefficient
of friction, the longer the braking
distance.
If the rider increases braking
pressure to the extent that brak-
ing force exceeds the maximum
transferable limit, the wheels start
to lock and the vehicle loses its
directional stability; a fall is im-
minent. Before this situation oc-
curs the ABS will be activated
and the brake pressure adap-
ted to the maximally transferable
braking force. The wheels con-
tinue to turn and the driving sta-
bility is retained irrespective of
the road condition.
What are the effects of
surface irregularities?
Surface irregularities can cause
the wheels to lose contact tem-
porarily with the road surface. If
this happens the braking force
that can be transmitted 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 stability is main-
tained when the wheels regain
contact with the road surface.
At this instant the ABS must
assume an extremely low coef-
ficient 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 it registers the actual
circumstances, the system re-
acts instantly and adjusts braking
force accordingly to achieve op-
timum braking.
Rear wheel lift
Under very severe and sudden
deceleration, however, it is pos-
sible that the 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.
WARNING
Rear wheel lift due to severe
braking.
Risk of falling
When you brake sharply, bear
in mind that ABS control can-
not always be relied on to pre-
vent the rear wheel from lifting
clear of the ground.
What is the design
baseline for
BMW Motorrad ABS?
Within the limits imposed by
physics, the BMW Motorrad ABS
ensures directional stability on
any surface. The system is not
optimised for special require-
ments that apply under extreme
competitive situations off-road or
on the race course.
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