Watch 606x VEX HEX’s video on how they did direct 3600 RPM no cartridge motor for their flywheel. It saves gears, blue cartridges, and time on building.
plates!!! plates are not good for a flywheel. You really want c channel and bracing, such as the post a few posts up. Also, keps nuts on the flywheel bearings are not particularly good, the vibration following the flywheels high speeds will just vibrate the keps nuts off.