Originally Posted by
davida
I believe that it is 1lb rotating weight saving equals a 1lb reduction in rotational inertia + the 1 lb static saving, so would require a 2 lb reduction in static weight to provide the same reduction in overall reduction in inertia.
I think it only matters when you are accelerating either horizontally or going up a hill (force against gravitational acceleration).
Hmm I once would have been able to explain this properly, but alas no longer, I just realised I am not really a proper engineer any more.
davida
That's really not how it works. It depends not just on mass, but how that mass is distributed around the center of the object. You can't just say 1 pound rotating mass equals two of static.
IIRC this is discussed in Bicycling Science, and the effect of rotating mass on a bicycle is generally far less than you might think. I'll look it up later. The wheels really don't go around that fast.