Brake System With Bmw Motorrad Abs - BMW R nineT Rider's Manual

Brake system with
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BMW Motorrad ABS
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How does ABS work?
The amount of braking force that
can be transferred to the road
depends on factors that 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 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-
z
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
can occur, ABS intervenes and
adapts braking pressure to the
maximum transferable braking
force. The wheels continue to
turn and the driving stability 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 possible 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.