Bike Storage: Wall mounts, stands, lock-ups, sheds, etc.

6mm, 8mm, 12mm, 16mm, then 20mm.
Someone can do the maths, but this splits the volume to be removed (not equally), across the 5 drill bits.

6mm: 28.3mm² = pi * 3²
8mm: 22.0mm² = pi * (4²-3²)
12mm: 62.8mm² = ...
16mm: 88.0mm²
20mm: 113.1mm²