Cycles — Safety requirements for bicycles — Part 6: Frame and fork test methods

This document specifies the frame and fork test methods for ISO 4210‑2.

Cycles — Exigences de sécurité pour les bicyclettes — Partie 6: Méthodes d'essai du cadre et de la fourche

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Status
Published
Publication Date
10-Jan-2023
Current Stage
6060 - International Standard published
Due Date
12-Sep-2022
Completion Date
11-Jan-2023
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ISO 4210-6:2023 - Cycles — Safety requirements for bicycles — Part 6: Frame and fork test methods Released:11. 01. 2023
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INTERNATIONAL ISO
STANDARD 4210-6
Third edition
2023-01
Cycles — Safety requirements for
bicycles —
Part 6:
Frame and fork test methods
Cycles — Exigences de sécurité pour les bicyclettes —
Partie 6: Méthodes d'essai du cadre et de la fourche
Reference number
ISO 4210-6:2023(E)
© ISO 2023
---------------------- Page: 1 ----------------------
ISO 4210-6:2023(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2023

All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on

the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below

or ISO’s member body in the country of the requester.
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Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
© ISO 2023 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 4210-6:2023(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction .................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 Frame test methods ..........................................................................................................................................................................................1

4.1 Frame — Impact test (falling mass) .................................................................................................................................... 1

4.1.1 General ........................................................................................................................................................................................ 1

4.1.2 Test method ............................................................................................................................................................................ 2

4.2 Frame and front fork assembly — Impact test (falling frame) .................................................................... 4

4.2.1 General ........................................................................................................................................................................................ 4

4.2.2 Test method ............................................................................................................................................................................ 4

4.3 Frame — Fatigue test with pedalling forces ................................................................................................................ 6

4.3.1 General ........................................................................................................................................................................................ 6

4.3.2 Test method ............................................................................................................................................................................ 6

4.4 Frame — Fatigue test with horizontal forces ............................................................................................................. 8

4.4.1 General ........................................................................................................................................................................................ 8

4.4.2 Test method ............................................................................................................................................................................ 9

4.5 Frame — Fatigue test with a vertical force .................................................................................................................. 9

4.5.1 General ........................................................................................................................................................................................ 9

4.5.2 Test method ......................................................................................................................................................................... 10

4.6 Rear brake mount tests ............................................................................................................................................................... 11

4.6.1 General ..................................................................................................................................................................................... 11

4.6.2 Static rear brake torque test ................................................................................................................................. 11

4.6.3 Rear brake mount fatigue test.............................................................................................................................12

5 Fork test methods ............................................................................................................................................................................................14

5.1 Suspension forks — Tyre-clearance test ...................................................................................................................... 14

5.2 Front fork — Tensile test ............................................................................................................................................................ 14

5.2.1 Test method — Suspension fork ........................................................................................................................ 14

5.2.2 Test method — Rigid, non-welded fork ....................................................................................................... 14

5.3 Front fork — Static bending test ......................................................................................................................................... 14

5.4 Front fork — Rearward impact test ................................................................................................................................. 15

5.4.1 Test method 1 ..................................................................................................................................................................... 15

5.4.2 Test method 2 (only for forks made entirely of metal) .................................................................. 17

5.4.3 Test method 3 ..................................................................................................................................................................... 17

5.5 Front fork — Bending fatigue test and rearward impact test .................................................................. 18

5.6 Forks intended for use with hub or disc brakes..................................................................................................... 19

5.6.1 General ..................................................................................................................................................................................... 19

5.6.2 Fork for hub/disc brake — Static brake-torque test........................................................................ 19

5.6.3 Fork for hub brake — Brake mount fatigue test .................................................................................22

5.6.4 Fork made of composite materials designed for disc brakes ...................................................23

5.7 Fork steerer tube and stem assembly — Fatigue test ...................................................................................... 24

5.7.1 General ..................................................................................................................................................................................... 24

5.7.2 Test method ......................................................................................................................................................................... 24

Annex A (informative) Dummy fork characteristics .......................................................................................................................26

Annex B (normative) Fork mounting fixture ...........................................................................................................................................28

Annex C (informative) Suspension frames — Tyre-clearance test ...................................................................................29

iii
© ISO 2023 – All rights reserved
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ISO 4210-6:2023(E)
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.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www.iso.org/patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to

the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see

www.iso.org/iso/foreword.html.

This document was prepared by Technical Committee ISO/TC 149, Cycles, Subcommittee SC 1, Cycles

and major sub-assemblies, in collaboration with the European Committee for Standardization (CEN)

Technical Committee CEN/TC 333, Cycles, in accordance with the Agreement on technical cooperation

between ISO and CEN (Vienna Agreement).

This third edition cancels and replaces the second edition (ISO 4210-6:2015), which has been technically

revised.
The main changes are as follows:
— improvement of 4.3;
— improvement of 4.4;
— improvement of 4.5;
— addition of 4.6;
— improvement of 5.4;
— improvement of 5.6;
— change of test equipment for 5.6;
— addition of 5.7.
A list of all parts in the ISO 4210 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www.iso.org/members.html.
© ISO 2023 – All rights reserved
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ISO 4210-6:2023(E)
Introduction

This document has been developed in response to demand throughout the world, and the aim has been

to ensure that bicycles manufactured in conformity with this document will be as safe as is practically

possible. The tests have been designed to ensure the strength and durability of individual parts as well

as of the bicycle as a whole, demanding high quality throughout and consideration of safety aspects

from the design stage onwards.

The scope has been limited to safety considerations, and has specifically avoided standardization of

components.
If the bicycle should be used on public roads, national regulations apply.
© ISO 2023 – All rights reserved
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INTERNATIONAL STANDARD ISO 4210-6:2023(E)
Cycles — Safety requirements for bicycles —
Part 6:
Frame and fork test methods
1 Scope
This document specifies the frame and fork test methods for ISO 4210-2.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments) applies.

ISO 4210-1, Cycles — Safety requirements for bicycles — Part 1: Vocabulary

ISO 4210-2:2023, Cycles — Safety requirements for bicycles — Part 2: Requirements for city and trekking,

young adult, mountain and racing bicycles

ISO 4210-3:2023, Cycles — Safety requirements for bicycles — Part 3: Common test methods

ISO 4210-5:2023, Cycles — Safety requirements for bicycles — Part 5: Steering test methods

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 4210-1 apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Frame test methods
4.1 Frame — Impact test (falling mass)
4.1.1 General

Manufacturers of frames are permitted to conduct the test with a dummy fork (see Annex A) fitted in

place of a front fork.

Where a frame is convertible for male and female riders by the removal of a bar, test it with the bar

removed.

Where a suspension fork is fitted, test the assembly with the fork extended to its unloaded free length.

Where a rear suspension system is incorporated in the frame, secure the suspension in a position

equivalent to that which would occur with an 80 kg rider seated on the bicycle. For young adult bicycles,

secure the suspension in a position equivalent to that which would occur with a 40 kg rider seated on

the bicycle; if the type of suspension system does not permit it to be locked, then replace the spring/

© ISO 2023 – All rights reserved
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ISO 4210-6:2023(E)

damper unit by a solid link of the appropriate size and with end fittings similar to those of the spring/

damper unit.
4.1.2 Test method

Assemble a roller of mass less than or equal to 1 kg and with dimensions conforming to those shown in

Figure 1 in the fork. The hardness of roller shall be not less than 50 HRC at impact surface. If a dummy

fork is used in place of a fork, the bar shall have a rounded end equivalent in shape to the roller. Hold

the frame-fork or frame-bar assembly vertically with clamping to a rigid fixture by the rear-axle

attachment points as shown in Figure 1.

Rest a striker of mass 22,5 kg on the roller in the fork dropouts or on the rounded end of the dummy fork

and measure the wheelbase. Raise the striker to a height of h above the low-mass roller and release it

to strike the roller or the steel bar at a point in line with the wheel centres and against the direction of

the fork rake or rake of the bar. The drop heights are given in Table 1. The striker will bounce and this is

normal. When the striker has come to rest on the roller or dummy fork, measure the wheelbase again.

If the fork fails, the frame shall be tested with a dummy fork.
NOTE See ISO 4210-3:2023, Annex B.
Table 1 — Drop heights
Dimensions in millimetres
City and trekking Young adult
Bicycle type Mountain bicycle Racing bicycle
bicycle bicycle
Drop height, h 180 180 360 212
© ISO 2023 – All rights reserved
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ISO 4210-6:2023(E)
Dimensions in millimetres
Key
1 wheelbase
2 permanent deformation
3 22,5 kg striker
4 low-mass roller (1 kg max.)
5 rigid mounting for rear-axle attachment point
6 direction of rearward impact
h drop height
Figure 1 — Frame and front fork assembly — Impact test (falling mass)
© ISO 2023 – All rights reserved
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ISO 4210-6:2023(E)
4.2 Frame and front fork assembly — Impact test (falling frame)
4.2.1 General

Manufacturers of complete bicycles shall conduct the test with the frame fitted with the appropriate

front fork.

For manufacturers of frames, where the fork intended for the frame is not available, the test can be

conducted with the frame fitted with a fork which meets the requirements of the fork impact test as

described in ISO 4210-2:2023, 4.9.6.

Where a frame is convertible for male and female riders by the removal of a bar, test it with the bar

removed.

Where a suspension fork is fitted, it shall be at its unloaded length prior to the impact. If the spring/

damper unit can be locked, it shall be locked in its unloaded length position. If the spring/damper

cannot be locked, use one of the two following alternative procedures:
— secure the fork at its extended length by an external locking method, or

— replace the fork by a rigid fork which is known to meet the requirements of the impact test described

in ISO 4210-2:2023, 4.9.6 and of a length which is consistent with an 80 kg (in case of young adult

bicycles, apply 40 kg) rider seated in a normal riding position on the bicycle when it is equipped

with the suspension fork.

Where a rear suspension system is incorporated in the frame, secure the spring/damper unit in a

position equivalent to that which would occur with an 80 kg (in case of young adult bicycles, apply

40 kg) rider seated on the bicycle; if the type of suspension system does not permit it to be locked, then

replace the spring/damper unit by a solid link of the appropriate size and with end fittings similar to

those of the spring/damper unit.
4.2.2 Test method

Conduct the test on the assembly used for the test in ISO 4210-2:2023, 4.8.2 or, in the case of a frame

manufacturer who does not make forks, with the same frame with a suitable fork fitted (see 4.2.1).

As shown in Figure 2, mount the frame-fork assembly at its rear axle attachment points so that it is free

to rotate about the rear axle in a vertical plane. Support the front fork on a flat steel anvil so that the

frame is in its normal position of use. Securely fix mass m to the seat-post as shown in Figure 2 with

the centre of gravity at distance D (= 75 mm) along the seat-post axis from the insertion point, and fix

masses of m and m (see Table 2) to the top of the steering head and the bottom bracket, respectively,

2 3
as shown in Figure 2.

Measure the wheelbase with the three masses in place. Rotate the assembly about the rear axle until

the distance between the low-mass roller and the anvil is h , then allow the assembly to fall freely to

impact on the anvil.

Repeat the test and then measure the wheelbase again with the three masses in place and the roller

resting on the anvil.

Table 2 — Drop heights and distribution of masses at seat-post, steering head, and bottom

bracket
City and trekking Young adult bicy-
Bicycle type Mountain bicycle Racing bicycle
bicycle cle
Mass 1
Seat-post, m 50 40 30 30
© ISO 2023 – All rights reserved
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ISO 4210-6:2023(E)
TTabablele 2 2 ((ccoonnttiinnueuedd))
City and trekking Young adult bicy-
Bicycle type Mountain bicycle Racing bicycle
bicycle cle
Mass 2
Steering head, m 10 10 10 10
Mass 3
Bottom bracket, m 30 20 50 50
Drop height, h
200 200 300 200
Dimensions in millimetres
Key
1 wheelbase
2 permanent deformation
3 mass 1 (m )
4 mass 2 (m )
5 mass 3 (m )
6 rigid mounting for rear-axle attachment point
7 steel anvil
D distance to the centre of gravity (75 mm)
h drop height
Figure 2 — Frame and front fork assembly — Impact test (falling frame)
© ISO 2023 – All rights reserved
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ISO 4210-6:2023(E)
4.3 Frame — Fatigue test with pedalling forces
4.3.1 General
All types of frame shall be subjected to this test.

In tests on suspension frames with pivoted joints, adjust the spring, air pressure, or damper to provide

maximum resistance, or, for a pneumatic damper in which the air pressure cannot be adjusted, replace

the suspension unit with a rigid link, ensuring that its end fixings and lateral rigidity accurately

simulate those of the original unit. For suspension frames in which the chain stays do not have pivots

but rely on flexing, ensure that any dampers are set to provide the minimum resistance in order to

ensure adequate testing of the frame (see Annex C for more information).

Where a suspension frame has adjustable brackets or linkages to vary the resistance of the bicycle

against the ground-contact forces or to vary the attitude of the bicycle, arrange the positions of these

adjustable components to ensure maximum forces in the frame.
4.3.2 Test method

Use a frame/fork assembly fitted with standard head tube bearings for the test. The front fork may

be replaced by a dummy fork (see Annex A) of the same length and at least the same stiffness as the

original fork.

NOTE If a genuine fork is used, failures of the fork are possible; therefore, it is recommended that for

convenience, a dummy fork stiffer and stronger than the genuine fork be used.

Where a frame is convertible for male and female riders by the removal of a bar, test it with the bar

removed.

Mount the frame assembly on a base as shown in Figure 3 with the fork or dummy fork secured by its

axle to a rigid mount of height R (the radius of the wheel and tyre assembly ±30 mm) and with the hub

free to swivel on the axle. Secure the rear dropouts by means of the axle to a stiff, vertical link of the

same height as that of the front, rigid mount, the upper connection of the link being free to swivel about

the axis of the axle but providing rigidity in a lateral plane, and the lower end of the link being fitted

with a ball-joint.

Fit a crank, chain wheel and chain assembly or, preferably, a strong, stiff, replacement assembly to the

bottom bracket as shown in Figure 3.

If the specifications of the fully assembled bicycle are known, either a) or b) shall be selected. In this

case, L shall be the same as the crank length of the bicycle.

If the specifications of the fully assembled bicycle are not known (e.g. frame manufacturer), b) shall be

selected. In this case, L shall be 175 mm.

a) If a crank/chain-wheel assembly is used, incline both cranks forwards and downwards at an angle

of 45° (accurate to within ±2,0°) to the horizontal and secure the front end of the chain to the

middle chain wheel of three, the smaller chain wheel of two, or the only chain wheel. Attach the

rear end of the chain to the rear axle and perpendicular to the axis of the axle.

b) If an adaptor assembly is used (as shown in Figure 3), ensure that the assembly is free to swivel

about the axis of the bottom-bracket and that both replacement arms are L and that they are both

inclined forwards and downwards at an angle of 45° (accurate to within ±2,0°) to the horizontal.

Secure the position of the crank replacement arms by a vertical arm (which replaces the chain

wheel) and a tie rod which has ball joints at both ends and which is attached to the rear axle

perpendicular to the axis of the rear axle.

The length of the vertical arm (R ) shall be 75 mm, but if the chain stay and tie rod interfere, the R

c c
length may be adjusted with the following Formula (1):
© ISO 2023 – All rights reserved
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ISO 4210-6:2023(E)
R = (1)
180
2sin( )
where

n number of teeth (the middle chain wheel of three, the smaller chain wheel of two, or the only

chain wheel);
p chain pitch (link length, 12,7 for most bicycles) (mm).
Tolerance for R shall be ±5 mm.

The axis of the tie rod shall be parallel to and 50 mm ± 5 mm from the vertical plane through the

centreline of the frame.

Subject each pedal spindle (or equivalent adaptor component) to a repeated downward force of F at

a position 150 mm from the centreline of the frame in a vertical, transverse plane and inclined at 7,5°

(accurate to within ±0,5°) to the fore/aft plane of the frame as shown in Table 3 and Figure 3. During

application of these test forces, ensure that the force on a “pedal spindle” falls to 5 % or less of the peak

force before commencing application of the test force to the other “pedal spindle”.

Apply the test forces for 100 000 test cycles, where one test cycle consists of the application and removal

of the two test forces. The maximum test frequency shall be maintained as specified in ISO 4210-3:2023,

4.5.
Table 3 — Forces on pedal spindle
Forces in newtons
City and trekking
Bicycle type Young adult bicycle Mountain bicycle Racing bicycle
bicycle
Force, F 1 000 1 000 1 200 1 100
© ISO 2023 – All rights reserved
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ISO 4210-6:2023(E)
Key
1 rigid mount
2 vertical link
3 ball joint
4 adaptor assembly
5 vertical arm
6 tie rod
7 centreline of tie rod
F repeated downward force
L length of crank replacement
R height of rigid mount and vertical link
R length of vertical arm
Figure 3 — Frame — Fatigue test with pedalling forces
4.4 Frame — Fatigue test with horizontal forces
4.4.1 General

Where a frame is convertible for male and female riders by the removal of a bar, remove the bar.

It is not necessary for a genuine fork to be fitted, provided that any substitute fork is of the same length

as the intended fork (see Annex A) and it is correctly installed in the steering-head bearings. For a

suspension fork, lock it at a length which correspond to the manufacturer’s recommended sag or 25 %

if no specification, either by adjusting the spring/damper or by external means. For a suspension fork

without sag adjustment system, lock it in a position equivalent to that which would occur with an 80 kg

(in case of young adult bicycles, apply 40 kg) rider seated on the bicycle.

In tests on suspension frames with pivoted joints, lock the moving part of the frame into a position

as would occur with the manufacturer’s recommended sag or 25 % if no specification. For a shock

absorber without sag adjustment system, lock it in a position equivalent to that which would occur with

an 80 kg (in case of young adult bicycles, apply 40 kg) rider seated on the bicycle. This can be achieved

by locking the suspension unit in an appropriate position or, if the type of suspension system does not

permit it to be locked, then the suspension system can be replaced by a solid link of the appropriate

compressed size. Ensure that the axes of the front and rear axles are horizontally in line, as shown in

Figure 4. For suspension frames in which the chain stays do not have pivots but rely on flexing, ensure

that any dampers are set to provide the minimum resistance in order to ensure adequate testing of the

frame.
© ISO 2023 – All rights reserved
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ISO 4210-6:2023(E)

Where a suspension frame has adjustable brackets or linkages to vary the resistance of the bicycle

against the ground-contact forces or to vary the attitude of the bicycle, arrange the positions of these

adjustable components to ensure maximum forces in the frame.
4.4.2 Test method

Mount the frame in its normal attitude and secured at the rear dropouts so that it is not restrained in a

rotary sense (i.e. preferably by the rear axle) as shown in Figure 4. Ensure that the axis of the front and

rear axles are horizontally in line.

Apply cycles of dynamic, horizontal forces of F in a forward direction and F in a rearward direction to

2 3

the front fork dropouts for C cycles as shown in Table 4 and Figure 4, with the front fork constrained in

vertical direction but free to move in a fore/aft direction under the applied forces. The maximum test

frequency shall be maintained as specified in ISO 4210-3:2023, 4.5.
Table 4 — Forces and cycles on front fork dropouts
City and trekking Young adult
Bicycle type Mountain bicycle Racing bicycle
bicycle bicycle
Forward force, F
450 450 1 200 600
Rearward force,
3 450 450 600 600
Test cycles, C 100 000 100 000 50 000 100 000
Key
1 free-running guided roller
2 rigid, pivoted mounting for rear-axle attachment point
F dynamic, horizontal force in a forward direction
F dynamic, horizontal force in a rearward direction
Figure 4 — Frame — Fatigue test with horizontal forces
4.5 Frame — Fatigue test
...

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