Brake System With Bmw Motorrad Abs - BMW G 650 GS Sertão Rider's Manual

Brake system with
6
BMW Motorrad ABS
54
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 fric-
tion than a clean, 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
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
Even under severe braking, a
high level of tyre grip can mean
that the front wheel does not
lock up until very late, if at all.
Consequently, ABS does not in-
tervene until very late, if at all.
Under these circumstances the
rear wheel can lift off the ground,
and the outcome can be a high-
siding situation in which the mo-
torcycle 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.