Bosch ZEMO SU-E FS 12 Translation Of Original Operating Instructions page 170

7.5.3 Checking the chain
 Check chain for rust, damage and chain links
that are difficult to move.
 Replace rusted, damaged or difficult-to-move
chains since they will not withstand the tensile
loads from the drive and will soon break.
Contact specialist dealer.
7.5.4 Checking the chain tension
Notice
Excessive chain tension increases wear. If the
chain tension is too low, there is a risk that the
chain will slip off the chain wheels.
 Check the chain tension once a month.
7.5.4.1 Check tension in derailleur gears
The rear derailleur tensions the chain on pedelecs
with derailleur gears.
1 Check to see if the chain is sagging.
2 Gently press the rear derailleur forwards to
check whether it moves and whether it goes
back into position by itself.
 If the chain is sagging or the rear derailleur
does not go back into position by itself, contact
your specialist dealer.
7.5.4.2 Check tension in hub gear
Remove the chain guard on pedelecs with a
circumferential chain guard.
Figure 171: Checking the chain tension (example): 5 mm
upwards, 10 mm downwards = 15 mm deviation
1 Lift chain upwards. Measure the distance to the
centre. Press chain downwards. Measure the
distance to the centre.
MY22Z01 - 12_1.0_25.07.2022
Cleaning, servicing and inspection
2 Add the two values together to calculate the
deviation.
3 Check the chain tension at three to four points.
 If the deviation is greater than 20 mm, tighten
chain.
 If the deviation is less than 10 mm, Loosen
chain.
 If a hub gear is fitted, the rear wheel must be
pushed backwards and forwards to tighten the
chain. Contact specialist dealer.
 In the case of pedelecs with a hub gear or
back-pedal brake, the chain is tensioned by an
eccentric bearing or movable fork end in the
bottom bracket axle. Special tools and
specialist knowledge are required to tension
the chain. Contact specialist dealer.
7.5.5 Checking the belt for wear
Each chain has a wear limit. If this limited is
exceeded, the chain needs to be replaced.
Manufacturer
SHIMANO
KCM
SRAM
ROHLOFF
Table 54: Chain wear limit by manufacturer
7.5.5.1 Rough check
You can perform a rough check on the chain
wheel by hand on conventional chains
1 Place the chain on the largest chain wheel.
2 Lift the chain from the front to the centre of the
bike.
 If the chain can be lifted more than half a link
from the chain wheel, carry out a check or
contact your specialist dealer.
Wear limits
>1%
>0.8 mm per link
>0.8%
S: >0.1 mm per link
A: >0.075 mm per link
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