Page 33 - 2018-v.3-Part 2(EN)
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Dimensions in millimetres
Key
1 drive pulley disc (D 2 ≥ D 1 + 10)
Figure 7 — Drive pulley disc
4.15.3 Chain and drive belt protective device
A chain protective device shall, as a minimum, shield the side plates and top surface of the chain and the
chain wheel for a distance of at least 25 mm rearwards along the chain from the point where the chain
wheel teeth first pass between the side plates of the chain, and forwards round the outer chain wheel to
a horizontal line passing through the bottom-bracket axle centre [see Figure 8 a)].
A drive belt protective device shall, as a minimum, shield the side and top surface of the drive belt and
the front pulley for a distance of at least 25 mm rearwards along the drive belt from the point where the
tip circle of the pulley [circle B in Figure 8 b)] is intersected by the tip line of the belt [line C in Figure 8
b)], and forwards round the front pulley to a horizontal line passing through the bottom-bracket axle
centre [see Figure 8 b)].
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