[MetroMPG]

Thanks for the update, even if it didn't work out.

I'm going to give it a try. I've already made up a coro disc with 8 magnets around the outside edge -- closer to the edge is better -- less potential leverage.

Also, the disc sits flush inside the rim's bead/lip so it's not easy for a blast of wind to pry them off (though can't predict the effect of a simple sudden pressure difference)