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TBIS 79010:2019
4.3.3 Frame and front fork assembly – Fatigue test with pedalling forces
4.3.3.1 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.
For a suspension frame and front fork, lock it at a length equivalent to that with
maximum permissible total weight by adjusting the spring/damper or by external
means.
4.3.3.2 Requirement
When tested by the method described in 4.3.3.3, there shall be no visible cracks or
fractures in any part of the frame, and there shall be no separation of any parts of
the suspension system.
For composite frames, the running displacements (peak-to-peak values) at the points
where the test forces are applied shall not increase by more than 20 % of the initial
values (see 4.1.1.6).
4.3.3.3 Test method
Use a new frame/fork assembly fitted with standard head-tube bearings for the test.
4.3.3.3.1 single-lane
Mount the frame assembly on a base as shown in Figure 9 with the fork or dummy
fork secured by its axle to a rigid mount of height Rw (the radius of the wheel/tyre
assembly ± 30 mm) and with the hub free to swivel on the axle. Secure the rear
drop-outs 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 9 and described in a)
or b) below.
a) If a crank/chain-wheel assembly is used, incline both cranks forwards and
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