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a) Type A b) Type B
Figure 9 — Aerodynamic extension to handlebar — Torsional security test
4.9 Handlebar and stem assembly — Fatigue test
4.9.1 Test method for city and trekking, young adult, and mountain bicycles
4.9.1.1 Test method for stage 1 (out-of-phase)
Unless the handlebar and stem are permanently connected, e.g. by welding or brazing, align the grips
of portion of the handlebar in a plane perpendicular to the stem axis [see Figure 3 a)] and secure the
handlebar to the stem according to the manufacturer’s instructions.
Clamp the handlebar stem securely in a fixture to the minimum insertion depth as specified in
TBIS 4210-2:2016, 4.7.3, or in the case of a stem extension which is intended to be clamped to an
extended fork steerer, secure the extension using the manufacturer’s recommended tightening
procedure to an extended fork steerer which is secured in fixture to the appropriate length.
For handlebars where the manufacturer states that they are not intended for use with bar ends, apply
fully reversed forces of stage 1 out-of-phase F 6 at a position 50 mm from the free end for each
side of the handlebar for 120 000 cycles, with the forces at each end of the handlebar being out of
phase with each other and parallel to the axis of the fork steerer as shown in Figure 10 a). The
forces are given in Ta ble 7. The maximum test frequency shall be maintained as specified in TBIS
4210-3:2016, 4.5.
Where a bicycle manufacturer fits bar ends, fit the bar ends to the handlebar according to the
manufacturer’s tightening instructions but with the bar ends located in a plane perpendicular to the
handlebar stem axis and apply the out-of-phase forces to the bar ends, as shown in Figure 8 and Figure 11
a).
Where a handlebar manufacturer specifies that his handlebars are suitable for use with bar ends,
conduct the test with the out-of-phase forces applied to simulated bar ends, as shown in Figure 11 b).
If the handlebar meets the requirement as specified in TBIS 4210-2:2016, 4.7.7.2, remove any bar ends
and conduct stage 2 in phase F7 of the test with the assembly in the same mountings.
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