BJL wrote:To all those that don't think that the rotational mass of wheels has any affect:
I'm not a physicist. I did basic physics in high school. That's it. But enough to know that most physicists will try and tell you that the entire universe can be reduced to mathematical equations, time travel is possible and probably have blind faith in one religion or another.
I can only come to the conclusion that when the physicists on here are out buying wheelsets for their bicycles, weight doesn't even come into the equation (pun intended). The intelligent thing to do is to buy cheap, robust, deep dish aerodynamic steel rims lined with lead so you'll continue to roll further than everyone else when the pedaling stops. Why spend money on carbon? You said so yourselves.
No one says it had
no effect. What we are saying is that for most cycling it has a
negligible effect.
The impact of rotating mass on power demand is only a factor when accelerating, the rate of accelerations in cycling is generally very low and fairly infrequent, the differences in moments of inertia of different weight bicycle wheels is tiny, that as a proportion of total kinetic energy the rotational kinetic energy of the wheels is also very small, which all means that the impact on total power demand of a bit of extra rim mass is several orders of magnitude less than the primary energy demand factors. So small it's almost negligible - and in the links I provided earlier I provide a clear analysis of the impact of a lot of extra rim mass on hard accelerations, where such a factor has a very small effect.
And finally, under steady state conditions, differences in rotating mass/moment of inertia make zero difference.
Where reducing wheel mass provides most advantage is in the simple reduction in overall mass when climbing hills. Even so, doing so at the expense of aerodynamics is a trade off that may well not be worth it, much depends on the sustainable climbing speed of the rider.
Hence why those for whom performance really matters, they may choose to spend extra $ to obtaining wheels that are both light AND aero, which is really only attainable with carbon fibre. I can't speak for physicists' (or anyone's) choice of wheels since many factors besides weight and aero go into such a choice.
The good news is this is all high school physics.