| Introduction
to Motorcycles
Motorcycle Design
Braking
Vehicle Modifications
Conspicuity
Lane Use
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| ISSUE
STATEMENT |
Although motorcycles have sufficient braking power and traction
to enable them to stop in as short a distance as a typical car,
panic-braking a motorcycle
poses unique hazards and requires greater operator skill than stopping
a car in panic situations or in a skid.
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| WHERE
WE ARE |
The vast majority of motorcycles use an independent system for the
front and rear wheels, with a lever on the right handlebar controlling
the front brake and foot pedal controlling the rear brake. A small
number of motorcycles link the controls and an even smaller number
have a handlebar lever to control the rear brake. We know of no
current research that indicates which if any of these is more effective.
Braking seems to be one of the most difficult skills for a motorcyclist
to master. It is also one of the most critical. It is difficult
because most motorcycles have two separate brake-control systems,
one for the front wheel and one for the rear wheel. As the front
brake is applied, weight transfers to the front tire, which causes
available traction to vary as weight shifts, requiring the rider
to adjust pressure on each brake control in a maximum-performance
stop. As found in the Hurt Report, in a situation the motorcyclist
typically overbrakes the
rear and underbrakes the
front, even though weight transfer means the front brake must
do the majority of the braking. Overbraking can either cause loss
of steering control or total loss of control. If the rear wheel
is locked, the rider typically loses directional control. If the
front wheel locks, the rider is likely to crash due to loss of
stability.
Rider training courses, available for the last two decades, have
sought to develop improved motorcyclist braking skills. Greater
emphasis has been focused on proper braking technique and the
importance of the front brake. There seems to be a greater recognition
of the importance of front brake use than there was 20 years ago
when the Hurt Report was conducted. Failure to brake effectively
and loss of control during panic-braking continue to play a role
in motorcycle crashes.
Continued rider training and practice are key elements in assuring
maximum rider performance in a panic situation. This allows riders
to learn brake control during a maximum-braking stop, internalize
the process of a hard stop so they react automatically in a panic
situation, and deal with events such as rear-wheel lock-up. However,
even panic-braking practice involves risk, because locking
the front wheel can cause an immediate loss of control and a fall.
This makes it difficult for rider training organizations to train
riders to use the front brake to its full capability.
Motorcycle braking systems have steadily improved in terms of
power, control, and reliability and continue to do so. Virtually
all street motorcycles now have hydraulically actuated disc brakes,
at least on the front wheel. Most motorcycles use this type of
brake—which is self-adjusting for wear and more resistant
to fade and wet conditions than drum-type brakes—on the rear
wheel as well.
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| Many street motorcycles also have powerful dual disc
brakes on the front wheel, which provide more stopping power where
it is needed most. This is particularly true for sportbikes and
touring motorcycles. Cruisers, despite weights that are normally
heavier than other styles except touring motorcycles, often have
just a single disc brake in front, although this seems to be changing.
Two technical developments have sought to simplify braking control
and provide more effective braking. Linked
braking slows both wheels with a single control. Antilock
braking systems (ABS) allow the rider to apply maximum
braking force without fear of wheel lock-up and the resulting
loss of control, providing the bike is not leaned over. Under
many pavement conditions, antilock brake systems allow the rider
to stop a motorcycle more rapidly while maintaining steering control
even during situations of extreme, panic braking.
Although incidental and first-hand experience indicates either
of these systems can be effective in countering the problems faced
by a motor-cyclist in a panic stop, we know of no research that
shows how they perform in the field compared with similar bikes
fitted with standard brake systems. The added costs (particularly
for ABS) and reluctance to accept them by some experienced motorcyclists
have limited the adoption of these potentially effective systems.
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| WHERE
WE WANT TO BE |
We want motorcyclists to possess the skills to use their brakes
fully while maintaining control under all riding conditions, thus
avoiding some crashes.
We would like developments in brake systems, which offer better,
safer panic-stopping capability for motorcyclists, to continue
and be more widely adapted to all classes of motorcycles.
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| HOW
TO GET THERE |
Assuring that motorcyclists get maximum braking performance requires
training, research, and deployment of equipment that can provide
maximum-performance braking while minimizing the danger of a braking-induced
crash. To obtain the level of braking that is available even on
current machines, both experienced and inexperienced motorcyclists
need recurrent training (see Rider
Education & Training, page 17).
Several braking issues invite further study:
• The new technologies seem to promise shorter stopping
distances and overall safer stopping for motorcyclists. ABS in
particular can do much to eliminate the dangers of overbraking
in a straight line.
• Studies of how effectively linked-braking systems perform
in the field would tell whether they should be employed more widely.
• The effectiveness of braking systems that combine ABS
with a linked control should be explored.
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