That was a pretty puzzling result: he said that max speed was higher with the handlebar bag than without. It turns out that he'd recorded the ride on Strava so we downloaded his data file and looked at the speed. His max speed with the handlebar bag was a one-second anomaly where it jumped up by a couple of mph then in the next second it returned to normal. Without that one-second point, his max speed without the handlebar bag would have been higher. So his long blog post about the aero benefit of handlebar bags was based on that. We commented on his blog post explaining the one-second anomaly and he removed our comment but left the blog post up. (His GPS device was the iPhone he had in his pocket).

[Edited to add:] By "we" I meant, Tom Anhalt and I. I wasn't using the Royal We.