"Wavy" discs have been on bikes for years.
Originally Posted by marketing speil
The advantages of the wave discs are:
• The wave form aids self-cleaning of disc and pad.
• Up to 150 grams lighter than original, reduced unsprung weight.
• Lighter disc = less gyroscopic effect = better handling.
• Strong braking action with good braking "feel".
• Even wear of pad.
• The upper disc loses more heat (larger surface)
• The outer "teeth" can expand (grow) outwards when hot, therefore not causing the disc to warp.
• The constant change of contact area between disc and pad reduces the "grabbing" effect.