Graham might have a total meltdown if he ever watched a flywheel being trued ...

 

You mean the big lead hammer I have?

 

That's how it's done...

"After the high spots are located and marked, the wheels are removed and carried out of sight of the customer where they are professionally bashed with a heavy lead maul and then the process is repeated until satisfactory results are achieved."

 

You chaps may not have come across Velocettes. They have had pressed crankshafts like recent Harleys since the dawn of time and I have indeed witnessed the delicate touch of a lead hammer to true them. Not for the faint hearted! I must go and lie down for a few minutes....