Originally Posted by
asgelle
That is true. For a non-aero frame changing the rim in the rear will be 25% less effective than putting that same rim in the front. For a highly aero-optimized frame, the difference will be less (since the air hitting the rear wheel will be cleaner).
Yeah. Chris Yu talked about this on a cyclingtips podcast, and I *think* he was saying closer to half (though he also agreed with you and said it depends on how aero the rest of the frame is).