Page 30 - 20190101 part 6 (EN)

Annex A
(normative)

Dummy fork characteristics

The test forks shall be designed to mount in a manner similar to the original fork, or in a manner using
typical procedures (see Annex B).

The test forks, when mounted, shall be the same length (axle to race), L, as the longest fork designed for
use with the frame.

The deflection of the test fork shall be measured in the direction of the force application at the front
axle centre, from the resulting application of a vertical force of 1 200 N. The fork shall be secured in a
horizontal position by constraining the steerer tube by means of a false head tube (with bearings) equal
to 150 mm in length. The steerer tube shall be secured as in a bicycle with the crown race seat adjacent
to the false head tube lower bearing assembly (see Figure B.1 in Annex B).

a) The deflection ratio, D r, for the test fork for the horizontal loading fatigue test and the vertical
loading fatigue test shall not exceed the value of 1,0 when computed as follows:

(A.1)

where

D r is the deflection ratio;

K 1 is 1 417, a constant;

L is the fork length, expressed in millimetres;

δ is the deflection, expressed in millimetres.

EXAMPLE

Fork length L = 460 mm

Deflection δ = 6,85 mm, from which
Deflection ratio D r

1 417× 10 000× 6,85
=
3
460

= 0,99721 ≤ 1,0

b) The deflection ratio, D r, for the test fork for the impact test shall not exceed the value of 1,0 when
computed as follows:

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