Not so fast...
Inertia always matters.
Wheels are never rotating at a constant velocity; they are always "micro accelerating" in response to your pedal strokes.
Well that may be true but:
i. inertial load of a wheel won't affect the steady state speed one can sustain for a given power output
ii. the level of velocity variation is tiny* but in any case all that happens is the variations in velocity are of an ever so slightly different magnitude, and importantly
iii. this does not imply a different level of energy demand since conservation of energy applies and of course as has been pointed out:
iv. a wheel with higher moment of inertia also requires more energy to slow down at the same rate, so any energy put into the system to accelerate also helps to reduce the rate at which it slows down. IOW see point ii.
* For anyone that cares to look, I took a deeper dive into the issue of micro accelerations during steady state pedalling in this post: http://alex-cycle.blogspot.com.au/...-crank-velocity.html
For a rider on flat ground at 90rpm / 250W, the normalised velocity variation during a pedal stroke is +/-0.15%
I went further, examining the velocity variations during hard accelerations: http://alex-cycle.blogspot.com.au/...-crank-velocity.html
As the overall impact of additional wheel mass (or a higher moment of inertia) on one's ability to accelerate, well I examined some scenarios where acceleration on a bicycle is at its maximum, and hence where such differences in wheel moment of inertia would potentially matter the most.
Have a look at how tiny the impact of real world wheel mass (moment of inertia) differences are when considered, as Tom Anhalt says, as part of the entire system: http://alex-cycle.blogspot.com.au/...sum-of-parts-ii.html