Ducati SUPERBIKE 848 Owner's Manual page 59

Once the desired spring preload has been set, re-tighten the
upper lock nut.
E
Warning
Use a pin wrench to turn the preload adjusting nut.
Take special care when turning the nut, to avoid injuring
your hand by striking it violently against other parts of the
motorcycle if the wrench suddenly slips off the nut while
turning.
Warning
The shock absorber is filled with gas under pressure
and may cause severe damage if taken apart by unskilled
persons.
If you plan to carry a passenger and luggage, adjust the rear
shock absorber spring load to the maximum setting to
improve the handling characteristics of the motorcycle and
to avoid the possibility of ground contact. It may also be
necessary to adjust the rebound damping accordingly.
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