To put some numbers on this discussion:

Stage 21, 1989 TdF
Versailles-Paris ITT
1. Greg LeMond 24.5 km in 26:57 (54.545 kph)

Stage 1, 2005 TdF
Fromentine-Noimoutier en l'Ile
1. Dave Zabriskie, 19 km in 20:51 (54.64 kph)

But the important facts here are 1) the Versailes-Paris course had a
significant elevation loss, and a tailwind was reported during LeMond's
run, and 2) Zabriskie was able to accomplish this *precisely* because
of his attention to aerodynamics, not his power output, which is the
level at which otherwise performs.

Something else:

On the tablet aero stuff looks like it should help everyone regardless of
speed - perhaps a slow person even more. But in practice it simply doesn't
work that way. Slow riders are generally inexperienced riders and they can't
hold steady aero positions for long periods of time and so they simply
destroy the effects of any aero equipment from their discomfort.

This doesn't match my experience at all. Slow riders (at least in TTs)
are most often that way because 1) they seem unaware of the magnitude
of improvement that aero eqpt. can afford, often opting for lightweight
components, and 2) they generate significantly less power.

That's why again and again best Cat 4 and 5 TT times are set by guys on
standard racing bikes.

Even if this were true, which it is not (at least in my experience), it
doesn't discredit aero eqpt. at all, unless you can put some numbers on
the power output being generated.

And I will tell you this: having lowered my effective frontal area to
0.23 square meters, I can avg. 25 mph for 20 km, which beats lots of
Cat. 4s and even 3s, even though I'm a lousy Cat. 5 in any mass start
race.

There's a point at which a guy starts getting good at
TTing and that's the time he should start thinking about aero equipment.
Before that it's just a waste of money.

I don't consider that 31:10 for 20 km made me 'good,' but that's the
point at which I saw an old Hooker, grabbed it, tricked it out mostly
in the way Andy describes (but with some custom touches as well --
home-made 32 cm-wide handlebars), and did what I never thought I could
do -- break a half an hour (29:56, to be precise) on an out-and-back 20
km course -- on only 237 W. This put me in a virtual tie with Chris
Mayhew, a bona fide Cat. 3 who can otherwise ride circles around me.
With some changes, I did 30:02 the next year on 229 W, and if all goes
well, I should be able to get to 29 flat, I believe.

Aero awareness can get you much more speed than light weight, but
unfortunately, it can't be as easily quantified as mass, and it isn't
measured in hundreds of units, i.e., "This [insert component] saves you
141 grams!" Call that 5 ounces, and it sounds much less impressive.

Charles Howe
"I have sworn eternal hostility to every influence of the metric system
over the mind of man."