Here is a set of the 6700 C-24's for under 400 with shipping.
http://www.ebay.com/itm/Shimano-WH-6...item19c960ec7c

The 7900's are like $1100[/QUOTE]

about the same price at nashbar - http://www.nashbar.com/bikes/Product...2_506881_-1___

True. I don't know why I didn't check that first ;).
about the same price at nashbar - http://www.nashbar.com/bikes/Product...2_506881_-1___[/QUOTE]

Can I get some supporting data for this? It's not that I don't believe you I'm just looking for some solid information.

This is something we dealt with all the time when I was working with race cars.

Human beings are:

1. Really crappy at feeling absolute values of forces;

2. Very sensitive to feeling deltas (changes) of forces; and

3. Very adaptable, so that "new" becomes "normal" very quickly (limiting the time window for which deltas can be sensed).

So unless you are doing back-to-back wheel swaps, you probably won't feel any difference at all, and that feeling of "difference" will vanish within a couple of minutes.

That's not the same as *making* a difference - the difference will be real and measurable. But you won't "feel" it.

By the end of race season, the race car would "feel" slow. After a winter of driving the truck, the first time back in the car would scare the crap out of me. By the end of that first session, it would be back to "normal".

As an aside, I think sometimes this is why some people are on the upgrade treadmill (cars, bikes, boats, whatever). At first you feel whatever change the upgrade made, but that quickly fades, and you start chasing the next fix....

DG

Technically speaking something more aerodynamic than something else will be faster, at all speeds.

So, for example, I read somewhere that a foot of cable housing is worth about 1 watt at some decent speed (let's say, for example's sake, 30 mph). So that means at 15 mph it'll save something too, maybe .3 watts. At 10 mph, maybe 0.1 watts.

Of course you may not notice a 0.1 watt difference at 10 mph. I sure as hell wouldn't notice. But, technically, for benchtop racers, there's an aero benefit at 10 mph.

By definition any aero reduction takes place at all speeds (pending laws of fluid dynamics, I'm sure at 22,000 mph it's different, and at 0.1 mph it's different, but for say 10-60 mph, it applies).

The more pertinent question, i.e. the real world question, is whether you'll notice a change or not.

I've experimented and discarded some aero ideas of my own. I've tried a LOT of different aero wheels, from the early-mid 90s on (starting with the Specialized TriSpoke, which ended up medaling in the 1988 Olympic ROAD race). I built up a slew of Zipp rimmed wheels, before they ever made a hub or a spoked wheel (they had disk and 3-spoke wheels). I tried the aluminum Campy wheels (original Shamal, Vento), Spinergy Rev-X (all generations, and all flavors of the last generation). I even tried low buck solutions, creating my own J-Disk by literally taping over a wheel with packing tape.

I'm a firm believer in aero wheels. I've swapped wheels, ridden aero and non-aero back to back, spent 2 hours doing repeated sprints, testing top speeds, etc etc etc. In fact I still have my list in my head, in order of preference, and I'll put a "star rating" on each one based on my old data:
1. TriSpoke (now sold as a HED3 or H3D), 4.8 stars
2. Zipp 440 (so a 58mm rim, although now I think that a 90 mm rim may overtake this spot, and even sit at #1), 4.6 stars
3. Spinergy Rev-X, 4.4 or 4.5 stars
4. Zipp 340 (38?mm rim), Shamal/Vento (aero wheels, 12 spoke Shamals, 16 spoke Ventos), 4.4 stars
5. Box section rims (Record Crono 28h), 4.2 stars

In 2010 I figured the next bike design thing for me to try would be an aero frame. For me I saw waterbottles as one of the main detractors from aero framed bikes. get a nice sleek profile, narrow as heck, so skinny it's almost invisible to the wind, then stick two huge cylinders on it.

Well what if I had no bottles?

I decided to experiment with that. I tried to get a narrow profile, NACA shaped tubing, etc. I planned on running no cages, no bottles. I'd run a CamelBak instead, and even bought a small CamelBak as well as a built-in-jersey one.

What did I notice?

Nothing, really. I noticed that I couldn't judge how much fluid I had left in my CamelBak. It moved when I sprinted out of the saddle.

Did I have an aero difference? I'm sure I did, with no bottles and NACA aero profile tubes. Did I notice it?

No.

Maybe I saved 0.1 watts. Who knows? I know it didn't affect me, regardless of what officially/technically happened. I put cages/bottles on and raced my now-unaero bike for the rest of the season.

Disclaimer: I am not, nor will I ever be in this sport/hobby for more than pleasure and fitness. My aero wheels look good and make me happy.

I went from a pair of Fulcrum 7s to SRAM S60s. I didn't really perceive much if any difference in speed until I compared the wheels against another bike. My buddy and I would always tuck and coast down a long steep hill on a regular ride. He would consistently coast slightly farther and faster than I did until I swapped my wheels. The difference was definitely noticeable. Now I was actually pulling away from him. I know that's not very scientific, but it's really the only appreciable difference in speed that I noticed going to an aero wheelset.

For me the biggest difference is the way these wheels perform in windy conditions. I have compared them against an older set of 50mm CF wheels and against the 24mm aluminum wheels that I replaced. I was a little skeptical about claims regarding the toroidal (the sides of the wheels bulge) design of the rims (Zipp designed, not sure about other manufacturers), but they do an amazing job in the wind (head and cross). The bike stays true for the most part, with very little of the jerkiness associated with riding in the wind.

Is that enough of a difference to buy aero wheels? That's up to you.

I guess what would concern me most is this: Can I beat another rider with this wheel? Or better yet, could I beat myself riding the the less aero wheel?

A serious question, if I can put out 485watts for a minute on a flat section of road and get to a top speed of 31mph with 27mm aluminum wheels, would I be able to get to 32 or 33 mph with a 56mm aero wheel? If so, then it's absolutely worth it. If not, then it's worthless.

That's a serious question though, if anyone has experience with a waterrocket-type interval on aero wheels let me know.

Very Good points. My tourniquet is tight, just show me which needle is better.

This is obviously true, but you forgot to mention that air resistance is a cube function, which means that the faster you go ... the more it will -incrementally- matter.
At 10 mph the difference between an aero wheel and any other wheel will be hard to even measure ... but at 30 mph it will be quite big ... something like a second to a few seconds per kilometer.

The question is: can anyone "feel" a few seconds per kilometer?
I don't think so ... and until I see actual data of double blind tests conducted with placebo calculated in ... I will assume that no human being is able to "feel" the difference between doing a kilometer in 1:49 versus doing that same kilometer in 1:48.

If one is competing in a sanctioned race those seconds may mean the difference between winning and not winning ... obviously for that use it's great to have aero wheels.
I have a disc wheel and a 50mm front ... a great combination and a nice whooshwhoosh :)

Yes I agree, which is why my theoretical 1 watt savings goes to .3 at 1/2 speed and .1 at 1/3 speed.

I was answering in reference to the following statement:
which implies that there is a great benefit to having aero equipment at slow speeds.

Although true on paper (i.e. if you did 12 mph for 120 miles, you'll save a greater % of energy based on a given reduction in force or a increase in speed), the benefits of aero really come into play, for me, at higher speeds. I'm more concerned about picking up 1 mph at 30 mph (so about 3%) or saving enough gas to stay on the wheel when under extreme duress at high efforts.

What a lot of energy calculations don't take into account is the penalty for falling below a certain threshold. So, for me, if I slow down just a touch, and I mean I lose all of 5 or 10 feet, I'm not going 0.05 mph slower anymore - I'm going to be going 6 or 8 mph slower because I'm out of the draft. This is the case on group rides and in races, and that's where I care about performance. On my own, except when I draft stuff or do sprints, I really don't care; I go pretty slow when I ride solo.

Aero benefits are kind of like calculating mortgage payments. I can pay (as an example) $2k for my mortgage. Every day I can keep the $2k in a savings account, I get about 1/365% interest. But if I pay one day late, I would have to pay about $2200 (1% penalty). It's a digital thing, the late payment, and it undoes 365 days of keeping my money in my account. Would it kill me to pay 5 days early, losing 5/365% interest? No. But if I pay a bit late, then it becomes really, really expensive.

Likewise, with aero wheels (or anything aero), if I'm at my limit and the aero wheels (or light weight) help me keep a gap closed, I just bought myself a bunch of riding. If I can't close the gap or blow up because it takes 50 more watts energy every time I jump out of a turn, then I go from averaging 21->27 mph (group ride -> race) to averaging 17-19 mph (my pace).

Having said all that, I found that aero wheels (or lack thereof, depending on the situation) and wheel weight (or lack thereof) make the most difference for me. I also feel that looking down helps in top speed sprints, but I try to limit my time looking down because then I can't see where I'm going. My aero frame experiment, although it looked cool, didn't convince me it helped.

I forgot, I use Cane Creek Speed bars (mass start legal aero bars). They help too, but I'm at the front when I use them.

Depending on the wheels you might save 20W at 30MPH. If it's taking you 485W to do 31MPH then getting an extra 20W would be a little over 4% extra power. As a rough approx you can divide that power increase by 3 giving you a speed increase of 1.3% or less than .5MPH. So you won't get 32-33MPH but saving 20W is not worthless.