Aero Bars
It's hard to quantify...I'd say once I actually got used to the handling of aerobars, I probably added about 1mph to my avg 40k TT pace, but the excitement of knowing how to ride them and wanting to ride them helped me add another 2-2.5mph because my training improved so much.
It's very hard to know without a powermeter and a whole lot of testing. Anecdotally, I'd guess that riding in the aerobars nets me maybe 1 to 1.5 MPH.
empirically, i went from pedaling downhill after friends to coasting nicely along with them...that's got to be worth a few mph
I have a little shorty-ITU setup and I'd say it's given me a 1-1.5mph bump over a 40k ride, maybe I'm cranking harder when I'm in the aero position, maybe I'm thinking more about the speed and time... who knows. If anything I'd say they can't hurt your speed as long as you have a decent fit.
Weary is the path that does not challenge.
Short answer is: The faster you go the more they help (on a descent, for instance, you may see a 4mph increase (guessing). Resistance increases exponentially, so whereas you may see a 1mph difference at 18.5mph you could see a 4mph increase at 40mph. Whatever the case, the speed increase is more than enough to justify the purchase.
Greatness is only achieved by those who perpetually raise the expectations of themselves to the point where it ruins their life.
some say the slower you go the better they pay off because you're out there longer and stand to take greater benefit from the reduced resistance




How much time have you shreaded off of your avg mph once switching to an aero bar setup?