Airtaxi,
To answer your original question the weight (a vector quantity) due to effects of gravity on the mass of the blades remains unchanged.
Lu,
What JT & Pie have been saying is true, a few other ways to convince yourself …
Take a wheel off your push bike, spin it up and see if it gets any lighter....
[This message has been edited by Zeke (edited 04 July 2001).]