KTM 390 DUKE 2021 Owner's Manual page 158

13 BRAKE SYSTEM
156
–
Check the brake linings for minimum thickness
Minimum thickness
» If the minimum thickness is less than specified:
–
Change the rear brake linings.
–
Check the brake linings for damage and cracking.
» If there is wear or tearing:
–
Change the rear brake linings.
F00853-10
A
≥ 1 mm (≥ 0.04 in)
A
.