Page 100 - TBIS_15194-2019_(EN)_3nd

TBIS 15194:2019

4.3.12.7 Crank assembly – Fatigue test
4.3.12.7.1 Requirement

4.3.12.7.1.1 Requirement of the cranks positioned at 45° to the horizontal

When tested by the method described in 4.3.12.7.2, there shall be no fractures or
visible cracks in the cranks, the bottom-bracket spindle or any of the attachment
features, or loosening or detachment of the chain-wheel from the crank.

For composite cranks, the running displacements (peak-to-peak values) of either
crank at the point where the test forces are applied shall not increase by more than

20 % of the initial value (see 4.3.1.6).

4.3.12.7.1.2 Requirement of the cranks positioned at 30° to the horizontal (Special
requirements for mountain bicycles)

For mountain bicycles, two types of fatigue test are specified, one with the cranks
positioned at 45° to the horizontal to simulate the forces due to pedalling, and the
second test with the cranks positioned at 30° to the horizontal, which has been found

to simulate the forces due to the rider standing on the pedals during the descent of
hills. The two tests shall be conducted on separate assemblies.

When tested by the method described in 4.3.12.7.3, there shall be no fractures or
visible cracks in the cranks, the bottom-bracket spindle or any of the attachment
features, or loosening or detachment of the chain wheel from the crank.

For composite cranks, the running displacements (peak-to-peak values) of either
crank at the point where the test forces are applied shall not increase by more than

20 % of the initial value.

4.3.12.7.2 Test method with the cranks positioned at 45° to the horizontal

Mount the assembly of the two pedal-spindle adaptors, the two cranks, the
chain-wheel set (or other drive component), and the bottom-bracket spindle located

on its normal-production bearings in a fixture with bearing housings representative
of the bottom-bracket (as shown in Figure 42a). Incline the cranks at 45° to the
horizontal.

Prevent rotation by locating a suitable length of drive chain around the largest or
only chain-wheel and securing it firmly to a suitable support, or, for any other type of

transmission (e.g. belt-or shaft-drive) by securing the first stage of the transmission.
NOTE It is permissible to have the left crank in either of the two positions shown in

Figure 42a, provided the test force is applied in the appropriate direction as specified
in the next paragraph.

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