Originally Posted by merlinextraligh

Wut? Do you have an afro picked out to 4 feet wide?

Even the most optimistic data about aero helmets doesn't put the speed gain at anything approaching 2mph, particularly at 23mph.

The substantial majority of that speed increase was either placebo, or improving fitness.

Once you've got a good aero position on the bike, all the tweaks, like aero wheels, aero helmets, skin suits, not wearing gloves, water bottle placement, etc, are ways to shave seconds and pick up a fraction of a mph.

Meaningful at the margin when seconds count, but they don't get you multiple mph improvements.