ISO 14722:1998

INTERNATIONAL ISO
STANDARD 14722
First edition
1998-12-15
Moped and moped-rider kinematics —
Vocabulary
Cinématique relative au cyclomoteur et à son conducteur — Vocabulaire
A Reference number
Contents Page
1 Scope .1
2 Normative references .1
3 Steering system .1
3.1 Axis and angles of the steering assembly .1
3.2 Dynamic quantities of the steering assembly.2
3.3 Steering characteristics of the steering assembly.3
4 Suspension system .3
4.1 Suspension geometry .3
4.2 Suspension dynamic rates .4
5 Tyres and wheels.5
5.1 Tyre axis system and variables.5
5.2 Forces applied to tyres and their coefficients .6
5.3 Moments applied to tyres .8
5.4 Phenomena related with tyres.8
6 Basic principles of axis systems and kinematics .8
6.1 Axis systems.8
6.2 Horizontal axis systems.9
6.3 Component and assembly axis systems.9
6.4 Ground contact axes .9
6.5 Moped masses and weight distribution .11
©  ISO 1998
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Printed in Switzerland
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ISO ISO 14722:1998(E)
6.6 Moments of inertia. 11
6.7 Motion variables . 11
6.8 Forces . 15
6.9 Moments . 15
7 Directional dynamics. 16
7.1 Controls . 16
7.2 Control modes . 16
7.3 Moped response . 17
7.4 Steer properties . 18
7.5 Stability. 19
8 Moped motion characteristics. 19
9 Aerodynamic characteristics of the moped-rider combination . 21
9.1 Winds . 21
9.2 Aerodynamic variables . 21
9.3 Aerodynamic forces, moments and coefficients. 22
10 Riding postures and behaviours. 23
11 Tests . 24
11.1 Constant environment influence. 24
11.2 Changeable environment influence. 25
11.3 Other tests. 26
Bibliography. 31
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Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard ISO 14722 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee
SC 23, Mopeds.
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INTERNATIONAL STANDARD  ISO ISO 14722:1998(E)
Moped and moped-rider kinematics — Vocabulary
1 Scope
1.1  This International Standard defines terms, symbols and conventions related to moped and moped-rider
motions and kinematics and to the modelling thereof.
1.2  It does not deal with methods of measurement, nor with the units used in reporting the results, nor with
accuracy.
1.3  The definitions in this International Standard apply to two-wheeled mopeds as defined in ISO 3833.
1.4  This International Standard does not cover road mopeds which are controlled by a pedestrian or which are
used for the carriage of goods to the exclusion of persons.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this International Standard. For dated references, subsequent amendments to, or revisions of, any of these
publications do not apply. However, parties to agreements based on this International Standard are encouraged to
investigate the possibility of applying the most recent editions of the normative documents indicated below. For
undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC
maintain registers of currently valid International Standards.
ISO 3833:1977, Road vehicles — Types — Terms and definitions.
ISO 6725:1981, Road vehicles — Dimensions of two-wheeled mopeds and motorcycles — Terms and definitions.
3 Steering system
3.1 Axis and angles of the steering assembly
3.1.1
steer axis
z
H
rotational axis of the steering assembly for steering control which coincides with the axis of the steering stem and
with the axis of the steering head pipe
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ISO
3.1.2
steer angle
d
H
angle of motion of the steering assembly about the steer axis (3.1.1) which is zero when the front wheel plane is
parallel to the moped longitudinal plane
3.1.3
wheel steer angle
d
W
angle formed by the intersection with the road surface plane of the moped longitudinal plane and the front wheel
plane
3.2 Dynamic quantities of the steering assembly
3.2.1
steering velocity
&
δ
angular velocity of the sprung part of the steering assembly about the z -axis
f
3.2.2
steering velocity of the handlebars
&
δ
H
angular velocity of the handlebars about the z -axis
H
3.2.3
steer torque
torque about the (3.1.1)
steer axis
3.2.4
steer force
value obtained from dividing the steer torque (3.2.3) and the effective rotational radius of the steering handle
NOTE The effective rotational radius of the steering handle is the distance between the steer axis (3.1.1) and the centre
point of the steering handlegrip projected on the plane perpendicular to the steer axis.
3.2.5
steady state steer torque
torque applied to the steering handle in order to maintain the motion of the moped-rider combination in a given state
NOTE When the moped-rider combination is turning, this torque is classified as positive steer torque (3.2.5.1), neutral
steer torque (3.2.5.2) or negative steer torque (3.2.5.3).
3.2.5.1
positive steer torque
steady state steer torque (3.2.5) applied in the direction equal to that in which the moped-rider combination is
turning
3.2.5.2
neutral steer torque
amount of steady state steer torque (3.2.5) equal to zero, required when the moped-rider combination is turning
3.2.5.3
negative steer torque
steady state steer torque (3.2.5) applied in the direction opposite to that in which the moped-rider combination is
turning
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3.2.6
steady state steer force
value obtained from dividing the steady state steer torque (3.2.5) and the effective rotational radius of the steering
handle
3.2.7
stiffness of the steering assembly
resistance against the deformation caused by the loads applied to the steering assembly
NOTE There are torsional and bending stiffnesses.
3.2.8
friction torque of the steering assembly
torque about the steer axis (3.1.1) required to initiate the motion of the steering assembly which does not include
the friction between the tyre and the road surface
3.2.9
damping torque of the steering assembly
damping torque about the steer axis (3.1.1) at a certain steering velocity (3.2.1) which does not include the
damping between the tyre and the road surface
3.2.10
moment of inertia of the steering assembly
moment of inertia of the steering assembly about the steering axis (3.1.1) under defined load conditions
3.3 Steering characteristics of the steering assembly
3.3.1
steering under stationary conditions
steering operation of the moped-rider combination under stationary conditions
3.3.2
counter steering
positive action on the steering handle in order to compensate (cancel out) the change in the state of the moped
3.3.3
disturbed steer
very short and quick rotation of the steering handle caused by an outside disturbance
3.3.4
loss of control in steering
uncontrollable rotation of the steering handle caused by a disturbance
4 Suspension system
4.1 Suspension geometry
4.1.1
wheel plane
centre plane of the wheel which is perpendicular to the wheel spin axis
4.1.2
wheel centre
intersection of the wheel spin axis and the wheel plane (4.1.1)
4.1.3
front and rear wheel alignment
position of the front and the rear wheel planes relative to some reference frame planes
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4.1.4
steering system alignment
relation between the wheel(s) and the body or the road surface
NOTE This term is often applied to the fork off-set (4.1.8), castor (4.1.7), castor angle (4.1.6).
4.1.5
alignment variation
displacements and deformations of the suspension system caused by forces applied to the wheels
4.1.6
castor angle
t
See ISO 6725:1981, 6.12.
4.1.7
castor
See ISO 6725:1981, 6.11.
4.1.8
fork off-set
distance between the steering shaft centreline and the front wheel spin axis
4.1.9
vertical wheel travel
vertical distance between the wheel spin axis position when the suspension is fully stretched and when it is fully
compressed according to the manufacturer's indication
4.1.10
spring and/or damper stroke
displacement between the spring and/or
...