Seen this vid before, really surprised how freely it can spin.
Wonder why it doesnt do this when in the watch.
Hi Peter,
I believe in the Video the rotor was doing a free spin with minimal resistance because it's not connected to the winding gears.
In the typical automatic watch a major portion of the rotor's kinetic energy is converted into potential energy by the winding gears to be stored in the mainspring.
So the rotor is doing real work and does not spin freely in the watch case.
Having said that you can still observe the free spinning rotor in the Valjoux 7750 when you spin it in the non-winding direction. Due to its unidirectional winding design the Valjoux 7750 only winds in the clock wise direction and the rotor spins freely in the other direction. As you can probably infer from the infamous wobble of the Valjoux 7750, a free spinning rotor is not really a desirable feature in an automatic watch.