The second method consists in rounding to 45 grades the angles (or corners) of the brake pads using abrasive paper (grain 120), because it's the external perimeter of the pad that mainly activates the vibration.
In this first image PICTURE 3 we can see how it is the original brake pad.
In the following picture PICTURE 4 we see the same brake pad after rounding the angles
Who’s not used to mechanics probably will be surprised, but the disk inexorably consumes too because of the effect of friction, even though more slowly than the pads.
It is of fundamental importance, for your safety and for the performances of the braking system, to check regularly the state of use of disks and pads. The first have a limit thickness normally stamped on the disk itself (after the initials MIN. TH. Which means in fact “minimum thickness”), which when it's reached by the disk, the disk needs to be quickly substituted. If you use a disk not thick enough, besides of obliging (specially using used pads) the pistons of the pliers going out a lot, you risk another problem probably less obvious but still important particularly in the racing or exasperated use: the disk also absorbs part of the heat generated by the friction with the pads and disperses it in the ambient. If the mass of the disk decreases (as in the case of a consumed disk, of not enough thickness) its thermal capacity will be compromised too, not only its mechanical resistance. There is also the risk, specially on off-road motorcycles, that stones or bumps damage the disk or other components of the system, so it is necessary to check them regularly. Little by little the disk and/or the pads consume, you will notice that the oil level in the tank of the brake pump will decrease. This happens because the piston is obliged to go out more to compensate for the minor thickness of disk and/or pads, and this new space will have to be occupied by the oil, which level will decrease. It's not about (in this case) a consume of oil, but a low level is an important index of wear of the disk and/or of the brake pads.
The check of the disk is the verification of its being planar (making the wheel rotate, the disk shouldn't laterally swing), it’s the verification of the absence of scars or important scuffing, and it also consists in verifying that the thickness is greater than the minimum indicated by the constructor (usually, for specialized enduro, 2,5 mm for the front disk and 3,5 mm for the rear one), measure that has to be taken using a calipers or a micrometer. It also needs to be checked, specially on fixed disks, that the flange and the connections to the hub don't have cracks or mechanical distortions.
To rebore a crooked or damaged by deep scars disk is usually not suggested, because it also unavoidably implicates a reduction of the thickness, and so, despite the reparation would have a useful life, it would be brief.
The pads are usually considered consumed when they reach the thickness of 1mm, but also in this case it is good to consult the manual of your own motorcycle.
Always remember that the brakes are the most important part of the motorcycle in matter of active safety, and that efficient and well maintained brakes (which also includes the periodic substitution of oil) could save your life.