**Steve, in America, bigger (and more expensive) is *always *better and, the customer is always right.
Tom,
You are right. Forgive me for my momentary lapse of reason! 
"I was talking with the folks at Hed last summer (I live local to them) and the thought was that the vast majority of athletes (non-pro cyclist) should be on a 60mm wheel or a Hed3. "
The HED 3 is a heel that performs very well at yaw angles typically encountered by slower riders, and this makes it a good choice for these cyclists; the reason this wheel performs well in these conditions is tangential to Tomās hypothesis at best, and certainly not supportive of his conclusions.
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Regarding the wind issue,
I bought a new set of 808s just in time for a HIM relay I was doing this past Sept. I got to the start and had forgotten the front wheel. Bonehead. Fortunately, I had a Cosmic Carbone SL still in my truck from a ride I did earlier in the week. Iād had a small mishap and was going to take the wheel to the shop to be checked out. Instead, I ended up racing it.
On the rear, I had my 808 with a wheel cover.
It turned out to be a very windy day. Friends who were racing on 808s on the front told me they really had their hands full. I had no problems at all controlling the Carbone and had the fastest bike of the day (again ā¦ relay).
Incidentally, that 808/cover rear wheel weighs a freaking TON ā¦ but man-o-man is it fast. For the longest open stretch of the race the wind was hitting squarely from the side and yet I felt like I was getting a push. I was passing an awful lot of folks through that section.
Iād say if you have concerns about the wind, go with the 606.
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Must work pretty well for fast riders as well since more than a few of the top ITTās in the tour have been using them for some time. I do get your point though.
Tom, I donāt hold a candle to you in terms of experience or knowledge but I have to respectfully disagree with the underlying premise of your post.
I race mostly small events in the Pittsburgh area and some of these races have seriously steep hills. I have found that on these hilly courses (double digit grades arenāt unusual) riding a 1400gram Hed disc has been way faster than my 970 gram Flashpoint 60 rear.
The weight penalty is far less than the aerodynamic gains. And thatās averaging 21-23mph not in excess of 25mph.
Now if the race was straight up a steep hill say Pittsburghās Canton Ave. (37% grade) Then yes weight would matter more. But that would be true for all cyclists.
If your TT at 30mph or 20, IMO, a faster, (i.e. deeper) aerodynamic wheel will make you faster.
Newbie question - Iāve been watching ST for a while, and finally registeredā¦
So let me get this straight because I was thinking about getting aero wheels for the upcoming seasonā¦the debate that has been going on in this thread about 404 vs 808 is only about the front wheel - right? In the back I should want the deepest dish possible, if not a disk?
Be kind to such a a remedial questionā¦and I look forward to many posts in the future.
Yes, as deep as possible in the back.
I think this thread started about both front and back, drifted towards the front (my posts), and finally went to the back wheel (last post).
BTW- I think 808ās are a great set up, but I canāt recommend one for the front. That doesnāt make it a bad choice though- just my opinion. Definitely for the back though if you donāt get a disc.
The climb might not be long enough to net out the time savings from the weight difference. The climb probably has be a pretty long one, like 10-60 minutes long, like the Col de Vence in Ironman France (a category 2 climb in the Tour de France).
I am with you on the disk being fast- and fastest under almost all conditions. I use a rear disk (Zipp) for nearly everything, and used on at Ford Ironman Wisconsin and it worked quite well I think- at least I seemed to go up the hills OK and had a decent (for me) bike split at 5:37:something.
I only switch out to lighter wheels (Zipp 303ās) on a really mountainous course, which I seem to only go up about once every two or three years.
The HED 3 is a heel that performs very well at yaw angles typically encountered by slower riders, and this makes it a good choice for these cyclists;
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Youāre almost right. Itās a wheel that performs very well at the yaw angles at which slower riders think they encounter. Of course, they actually donāt. People always dramatically over-estimate the wind speed at .5 meters.
For the answer, we delve into the bowels of triathlon historyā¦ Set the wayback machine to the mid to late 80āsā¦
The wheel guys go back to the wind tunnel and re-evaluate wheel aerodyanmics based on this higher speed performance envelope for the pros that is now residing between 27-34 m.p.h. average speed. These are titannic averages seen only among the super human, 400+ average watt efforts of the Armstrongās, Zabriskes, Bassos and Cancelleras. Thes guys are skewed so far ouot of the normal performance envelope that they need a deeper section rim which presents a different aspect ratio for the ultra-high speeds they can average.
Bottom line: If you can average speeds on the bike well above 25 m.p.h. consistently then the 80mm deep rims may offer a benefit as compared to the 60ās. If youo are more like the rest of us, averaging up to 23 m.p.h. on a good day, then 60mm is probably an optimal balance between weight, aerodynamics and overall performance.
They may have thought that in the 80ās, but Greenwellās oft-quoted work published in the 1995 Aeronautical Journal pretty much threw that out the window. He demonstrated pretty clearly that the impact rotational speeds have on wheel aerodynamics is negligible.
Thatās why wheels are often tested at lower speeds and the results are normalized to 30mph. In Zippās propaganda, theyāve mentioned too that theyāve tested at difference speeds (20 and 30mph) and the results were proportional.
If a wheel starts going 200mph, then you may have somethingā¦
āyouāre almost rightā¦ā
Well, maybe you have different data than I do, but the info I have shows the h3 to be a wheel that comes into its own in yaw situations that are pretty difficult for a fast rider to seeā¦ Heck, the whole knock on this wheel at the zipp site is that its fantastic at 20 plus yaw, and bfd as a resultā¦
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āyouāre almost rightā¦ā
Well, maybe you have different data than I do, but the info I have shows the h3 to be a wheel that comes into its own in yaw situations that are pretty difficult for a fast rider to seeā¦ Heck, the whole knock on this wheel at the zipp site is that its fantastic at 20 plus yaw, and bfd as a resultā¦
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No, my argument is that even slower riders will rarely see those yaw anglesābecause they dramatically overstate the actual ground wind speed. Just for reference, Iāve done some WINDY-ASS ttās where the ground wind speed was measured at about 4-6 mph at .5 meters (think 'riding around some very flat valley where you can barely control your 3 spoke, getting almost blown off of the courseāthe actual gusts were about 8-12 mphāI know this since thereās a Wunderground measurement on the course, interestingly enough about 5 feet off of the groundā¦). If you asked someone in the parking lot, pretty much everyone would have said 'man, that had to be like 20-30 mph winds (including me)ā¦
"No, my argument is that even slower riders will rarely see those yaw anglesābecause they dramatically overstate the actual ground wind speed. "
Given that all your suppositions are correct, and If you mean angles like 20 degree, than yeah; You need to be going about 15mph to get a 20 degree wind on rider effect with 5mph winds. That is totally discounting the āgusts,ā and assuming your WU station to be accurate, which is not necessarily the case for ground level winds, which are by nature very localized phenomena - localized as in 5 feet away can be an order of magnitude difference.
So, weāre arguing right past each other.
As I said earlier, the whole knock on the H3 from the Zipp perspective is āBFd if a wheel rocks at 20 degrees. You wonāt ever see that.ā
My original point wasnāt that the H3 would be the killer ap for a slow rider because they would live in the 20 degree domain, rather the more universal truism that the slower you go, the higher the effective yaw angle of the wind, and the more likely you are to see benefit from the deeper/more surface area rims/wheels. While the magnitude of the advantage is what is up for debate, itās pretty darn clear that (all things being equal) the greater the surface area a wheel has, the better it is likely to perform in higher yaw situations (from a simple drag perspective, at least - weāre not talking about handling and other issues like āchuffing.ā)
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Iād be curious to know where you got your data. The three tests Iāve seen te Hed 3 is either right behind the Zipp 808 at almost all yaw angles, or right ahead.
What tire was used in the test you have? Is it 23mm wide? Thatād probably be an explanation for the Hed 3ās less than stellar low yaw performance. Itās max rim width is around 20mm, would you run a 26mm tire on a Zipp 808 and call it a good test.
With a 19-21mm tire, the Hed 3 becomes a consistent performer across all yaw angles. Whereas deep section wheels are specifically geared for the 5-12 yaw range.
A final thing to remember is when you look at wind speed constantly recorded at bike heights, it isnāt constant. The speeds you may see on the weather report are the average they are most often seeing. Wind is constantly going up and down second by second, minute by minute. This is why when run with the correct tire, the Hed 3 becomes such a great wheel.
Check out this wind speed recording, taken by a cyclist, for the means of understanding time trials. Wind is not predictable or constant.
http://wattagetraining.com/blog/greg/uploaded_images/SaltairWindData42607_BF39/wind2.png
"Iād be curious to know where you got your data. The three tests Iāve seen te Hed 3 is either right behind the Zipp 808 at almost all yaw angles, or right aheadā¦, blah blah blah "
ā¦and where, in anything I wrote, do you see anything contradictory to what you write?
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