BMW R 1250RS, Rider'S Manual

Page: 153 / 279

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
ABS?
If the ABS has to reduce braking
force on account of the circum-
stances described above, vibra-
tion is perceptible through the
handbrake lever.
When the handbrake 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 handbrake 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
same time as the brake lever is
pulled.
Rear wheel lift
Under very severe and sudden
deceleration, however, under cer-
tain circumstances it is possible
that the ABS will be unable to
prevent the rear wheel from lift-
ing 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 ABS?
Within the limits imposed by
physics, the ABS ensures dir-
ectional stability on any surface.
The system is not optimised for
special requirements that apply
under extreme competitive situ-
ations on the track. The driving
behaviour should be adapted to
actual driving skills and the road
conditions.
Special situations
The speeds of the front and rear
wheels are compared as one
means of detecting a wheel's
incipient tendency to lock. If
the system registers implaus-
ible values for a lengthy period
the ABS function is deactivated
for safety reasons and an ABS
fault message is issued. Self-dia-
gnosis has to complete before
fault messages can be issued.
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z Engineering details