Originally Posted by FBinNY

The issue isn't whether they're loose type or cartridge, but the configuration of the rolling elements.

Most cartridge bearings used on bikes are deep groove radial bearings, which can only handle rsdial loads, plus very light axial loads, more about staying located, than handling any thrust.

Unless you can expand the inner race, there's no way to change the radial preload, which is already built into them.

Axially loading them only pushes the elements sideways, forcing the balls to ride the sides of the grooves, and will rapidly destroy the bearing.

There are also angular contact cartridge bearings, which work the same as bike cup/cone systems, and therefore need proper axial preload. However, offhand, I don't know if any bike parts use these.

If you look at the MKS schematic, you'll see a pair of low profile radial bearings which carry most of the load, and a deep groove radial bearing at the end that keeps the pedal from sliding off the spindle.

This design simply cannot tolerate preload, and I'm not surprised that MKS doesn't want folks "fixing" them.