Losing weight will help with climbing but not speed on the flat. 600g won't help *much* with except by tdf standards.

Read

http://en.wikipedia.org/wiki/Bicycle...rotating_wheel

http://www.training4cyclists.com/how...on-alpe-dhuez/

Frankly, telling you the answer to your question wouldn't help you. Using the answer correctly requires more knowledge of physics than obtaining it. (However, a good approximation for a spoked wheel is too consider it as two point masses - one at the distance of the rim with mass of the rim + tyre + tube, the other at half the radius of the spokes and having the total mass of the spokes.)

But: aero resistance is a speed cubed law, which means it matters proportionately more as you go faster, and that you only get the cube root of power reductions as increased speed. Which is a way of saying that what you are doing is utterly pointless outside of a race.

Maths: Your rear wheel might be 10% of your total drag, cutting its drag by amazing 50% gives you an overall reduction in power use of 5%. You take the cube root of 1.05 to find out how much faster you're going - and its a might 1.6% speed boost. In the real world I'd expect you to get only a fraction of that. You'd almost certainly do better to fit latex inner tubes and reduce hysteresis energy - that would give you around a 10% reduction in rolling resistance and cost hardly anything. (Hmm - you're using slime and are probably crappy tyres: you should be able to get rr down by MUCH more than 10%!)

And, yes, I have a physics degree.