Aero at any speed? True or urban myth?

The amount of wind resistance increases by the velocity squared.  Wind resistance is a factor at all speeds and runners do, indeed, use a drafting effect.  However, the higher velocity, the larger percentage of overall power is used in overcoming wind drag.

If something gives an aerodynamic advantage with no compromises/sacrifices, then it's advantageous at any speed.  Thus, all else being equal, always opt for the more aerodynamic choice.  However, all else is not always equal and aerodynamic options sometimes come at the cost of other variables. When a racer is in a position where he has to make compromises between aerodynamics and other important factors (comfort, coolness, weight, mechanical efficiency)... then the speed is relevant to the decision.  The faster the speed, the more the tipping point is weighted toward aero.

This is pretty much what I was going to post as well.

Two aspects to consider here:aero position and aerodynamics.

Aero shouldn't only be considered for the aerodynamic benefit, but for the pressure it takes off of wrists and hands.  I know I'm opening a can of worms, but after 50 miles, I start to have numbness in one hand if I don't have access to aero bars.

I'm more comfortable aero than not.  I'll even go aero in a sustained gradual climb because of the comfort level.  But I guarantee I'm not moving fast.

I disagree that a runner in a draft cannot reduce his CdA as much as a cyclist in a draft. A runner has more x-sectional area at wind-risk, and also, they run at slower speeds than a bicycle, hence it will be easier to maintain a close distance safely and thus improve the draft effect.

I agree that for SOLO athletes, a runner cannot reduce draft as much as a cyclist, but as drafting is eminently legal in running races, the fact that the pros do not run-draft strongly indicates that there is a minimal-negligible aero benefit from drafting at slower speeds.

By this standard, it might actually be true that 'significant aero benefits don't come until you're at X speed on the bike' - which is one of the most anathema statements you can make here on BT despite lack of evidence supporting.

The equation with v^3 as well also strongly supports the concept that slower beginners should NOT get the same time savings as a rider at fast speeds, so it would be accurate to say beginners are not getting anywhere near as much benefit from their deep-dish race wheels as a fast rider if the equation played out that way in real-world situations.

One of the most COMMON things you'll here on this forum are:

"Speed benefits from aero gear end up being net the same for same distance traveled. While the faster rider gets a bigger mph drop, the slower rider overall gets the same time savings because they're on the course longer."

Do a search - this is by far the most common rationale for beginners by expensive aero gear like wheels for their bike.

I actually agree with your statement that there is no lower limit at which aero gear doesn't stop working, but I do believe the difference we're talking about are a lot smaller than people think on these forums - like trivial enough to be barely measurable at small speeds, honestly.

If pro marathoners don't find any benefit in drafting at 12mph, it's hard for me to believe that you'll get much of a time savings in a 40k bike at 15-16mph, which is trivially faster. Add the fact that most aero benefit measurements by wheels are done at high speeds where the gains are bigger (20+mph), and this supports this idea.

To date, I've never seen any real substantive data regarding time savings of aero gear by beginners riding at ,say, 15-17mph, more than isolated anecdotal incidents. 

I'm definitely playing devil's advocate here, but this is one of the most often asked questions and heated areas of debate - and to me, the data about pro marathoners really casts doubt on how much of a time savings you're getting when you're near their speed on a bike (like 15-16mph), and serious doubt on the concept that beginners save the same amount of time as fast cyclists because they're on the course longer. (I actually dont buy that one at all anymore.)

Again, not disagreeing that aero benefits occur at any speed (they obviously do), but disagree on the oft-cited key concept here:

That net time savings for aero gear for slow and fast riders is the same because beginners are on the course longer. 

When I'm talking run-drafting, I'm commenting on why pro running teams clearly do not have team-pacelines to drag their favorite runner to the finish. Yes, there is some 'drafting' going on, but it is all loose and informal - nothing like HTC pulling Mark Cavendish or a yellow jersey rider to a finish in an organized manner. If drafting really worked that well at 12mph, I'm sure we'd see it done.

I'm starting to be inclined to take the position (especially based on your formula) that time savings are significantly greater for riders at 20+mph and that this idea of having equal net time savings on the course for slow vs fast riders is not true despite it being commonly said on these forums.

How about you bring up the threads that lead to this belief since you have the question?  Then the responders can go from common ground.  Shane has done an excellent job explaining this, so what keeping you from accepting it?

No need to get personal here. I've always found Shane's responses very helpful and elucidating. I don't have an axe to grind, but I disagree when I see big discrepancies between theory and reality as practiced by the pros. (As per my marathoners not doing draftlines example.)

I'm still in the dark though on the conclusion - Shane, what is your  final take on the statement I posted above:

"That NET time savings for aero gear for slow and fast riders is the same because beginners are on the course longer."

Agree/disagree? I obviously value your judgment enough to ask!

A search for what I'm mentioning turned out thousands of threads - too many to go through individually, but this one should suffice as a started (scroll down to AndrewMTs response)

http://www.beginnertriathlete.com/discussion/forums/thread-view.asp?tid=263374&start=1

This question was brought up on "that other site" and the point was made that "faster riders save more watts and slower riders save more seconds".  That seems to be a simple way to sum it up.  There are more benefits than just amount of time you save.

And again, if this is true, why don't marathon runners, who would obviously get a significant aero benefit by closely running in a draft, safe those seconds during racing? You'll see them form loose packs, but they don't optimize their draft, even when going for the world record or Olympic gold. According to the statement you just made, marathoners (analogous to a 'slower rider) should benefit MORE over a 26 mile distance than a cyclist if the statement is in fact true.

 EDIT - actually, I'm coming around to seeing GSMacloed's point - missed it the first time. It has to do with the differences in resistance of running vs cycling. That makes more sense to me. 

Thanks gsmacloed!

This is an apples to oranges comparison as well.

You spend a large amount of your energy cycling overcoming air resistance to propel yourself forward.  When you're running, most of the resistance is provided by gravity, and that is what you spend your energy overcoming in order to continue forward.  I'm not sure why you're trying to directly compare two very obviously different things.

Just realized this as Gsmacloed pointed out above. Good to have experts on this forum! Thanks.

Through a quick google search, I found several sources recommending drafting like this one:

http://www.marathonandbeyond.com/choices/williams.htm

"How can biomechanics help the marathoner? Most of us who have run a marathon have used a simple biomechanical strategy. When running into the wind, we have drafted off another runner or, better yet, a group of runners. In doing so, we have reduced the adverse effects of air resistance, or drag. When we draft, the oxygen cost of running is reduced dramatically, improving running efficiency and saving energy for the latter part of the race. "

I'd like to say that I've seen runners draft in the Olympic marathon as well as NY, Boston, etc.

Edit: Realized as I posted this that three other people posted, but leaving this here as the article is at least a decent read.

If there are a thousand posts then it should be easy to find a handful to link.

And here is what Andrew said:

It doesn't say that they save the same time.

You do see some drafting / position jockeying in running -- look at an Olympic 1500m for example.  But I disagree that it's easier to maintain a close distance running.  On a bike you can be *right on* someone's wheel or even overlapping slightly to the side.  In a run you have to stay out of their kick.