Bill,

E=mc² is not a formula from classical mechanics, which is what you are
talking about here. The energy to get a wheel, or any other object,
spinning depends on its "inertial mass", which is usually called "moment of
inertia", and the effective radius. Calculus gives the formula E=1/2 IR²,
which is similar to the formula for a moving object, E=1/2 mv², where m is
the mass of the object and v is the velocity.

Now, once you get an object moving or spinning, there is NO energy required
to keep it doing that, unless there are losses. In a vehicle, losses are
friction, air resistance, and that hundred pound girlfriend's credit card
usage. The wheels on Lance's bike have to be light because of the need to
accelerate, decelerate, and turn. Big heavy mountain bike wheels would slow
him down, but not for the reasons you state.

Earle

"L.W. (ßill) Hughes III" > wrote in message
...
> Horsepower, or imagine the the force you would need to peddle your
> bicycle, now put your Jeep tire on the bicycle and peddle. E=mc². The E
> stands for energy. The m stands for inertial mass, which is similar to
> (but not the same thing as) weight. C squared stands for the speed of
> light multiplied by itself. I would say Lance Armstrong bike wheel are
> very light right about now in france, not like his mountain bike.
> God Bless America, ßill O|||||||O
> http://www.billhughes.com/
>
> RoyJ wrote:
> >
> > The reason you use a 13 pound flywheel is to allow maximum ACCELERATION
> > of the engine. The reason for lightweight tires is to allow
> > ACCELERATION. The reason to not take your girlfriend along is
> > ACCELERATION So what does weight have to do with steady state? (other
> > than the additional wear on the bearings?)
> >
> > L.W.(ßill) Hughes III wrote:
> >
> > > Hi Dave,
> > > To keep something turning takes more horsepower the heavier it
is,
> > > that's why the drag racers use a thirteen pound aluminum flywheel and
> > > lighter rims and tires. Of course, that flywheel also stores energy,
> > > that will made the stock V6 buick power CJ with it's fifty pound
> > > flywheel easily crawl over rocks that would easily stop a couple of
> > > hundred more horsepower in a 350" Chevy V8. I know taking your hundred
> > > pound girlfriend with you down the drag strip will cost you a tenth of
a
> > > second. As far as sprung and unsprung weight, all I know is it makes a
> > > great deal of difference in their ride and cornering ability, like
road
> > > racers need independent suspension to win.
> > > God Bless America, ßill O|||||||O
> > > http://www.billhughes.com/
> > >
> > > Dave Milne wrote:
> > >
> > >>I read somewhere that every lb of unsprung weight is worth 10 lb of
sprung
> > >>weight ; don't know if that's true or not.
> > >>
> > >>Dave Milne, Scotland
> > >>'91 Grand Wagoneer, '99 TJ