General Instructions; Bmw Motorrad Abs - BMW F800R Rider's Manual

General instructions

8
To find out more about engineer-
ing go to:
84
bmw-motorrad.com/technik

BMW Motorrad ABS

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, dry asphalt surface.
The lower the coefficient of fric-
z
tion, the longer the braking dis-
tance.
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 motorcycle loses
its directional stability; a fall is
imminent. 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, 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.
WARNING
Rear wheel lift due to severe
braking.
Risk of falling