Originally Posted by
Kevindale
Is it really? The weight of the shoe on the side that is driving the pedal stroke is helping you mash that pedal down, in a way that negates the weight on the other side. I suppose the extra mass might very very slightly degrade rapid acceleration, and one might pay an incredibly slight penalty on when climbing, but comfort is going to trump weight on a long ride.
Yes, technically it is rotating mass, but contrary to silly rules like "rotating weight costs double", not all rotating mass on a bike has the same cost. Rotating mass ~170 mm from the axis has a little over half the moment of inertia as weight at the wheel rim. Combine that with the roughly 1/3 angular velocity and the rotational effect of a couple dozen grams gets pretty far down into the noise.