Nick Müller wrote:
The other funny experience was, that what they sell as wheigh tlifting
disks are in reality the cheapest flywheels you can get.

Ummmmm - aren't those cast iron? Cast iron is not bad in compression
but an absolute disaster in tension and, IIRC, tension runs pretty high
in a flywheel. I close my eyes and see pie shaped pieces of material
whizzing about and through people at supersonic speeds. :-(

Ted