You want something in the 60mm or deeper range. Don't use a HED3 on that frame/fork unless you want to sacrifice some serious wattage.

Chris

Is that due to the aero profiles of the fork/frame?

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Ryan
Engineer. Duathlete. Roadie. Human.
CAPA Cycling

Yes.

The fork blades are too close to the wheel on the front. It might not be too bad on the back, but you'd have to test that out yourself.

Chris

Chris,
I know you've tested this out a bunch on your 650c bikes, but I don't know if we've ever seen any hard numbers on your results. So, forgive me if you've already shown this, but could you please give us a brief "tutorial" in your test methodology and the magnitudes of the differences you observed?

The main driver in my curiosity on this subject has to do with the fact that I'm considering picking up set of H3s for racing next year.

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http://bikeblather.blogspot.com/

It seems like HED should just put this topic to bed and give us some numbers. They make both deep dish and the H3 so it is not like they would lose a sales (I realize they are the exclusive on the H3 and there is tons of comp for deep dish). HED is in a position to control the conversation and say if you have X type frame or fork, this wheel combo is best for these reason and here is where to get it.
I have deep dish and love them and my wife has H3 and loves them. We both are on Cervelo so I have to assume one of us has a faster bike on paper, but who? If HED could show that and H3 is the way to go, I'd change jsut becasue the look cool on the car.

Well look what I found...not sure how helpful it is, but it has a lot of colors :)

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Ryan
Engineer. Duathlete. Roadie. Human.
CAPA Cycling

Hmmm ... I wonder exactly why the Flashpoint rim "needed" a Tangente tyre on it rather than a CX, and why Zipp never use VF records or other thin & fast tyres for the H3 ...

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AeroCoach UK
http://www.aero-coach.co.uk

Ok, the forks I have tested are the following (in order of worst to best with a Nimble Crosswind):

Kestrel (old version, not the threadless)
Reynolds Ouzo Pro
Profile BDC (steel steerer tube, nearly 700 grams)
Reynolds Ouzo Pro Aero
Oval Jetstream
Kinesys Wedge
Kinesys Carbon Aero
Older, wide crowned, narrow blade Colnago

Only the BDC, CarbonAero, and Wedge were tested with a HED3 (alu rim, Corsa CX tire), but they came out in the same order.
No front brake to speed up the fork switching. Brake hole taped.

Protocol:

4 runs each between 6:30 and 7:30 am. 1 run = 10 x 3/8 mile @ 25mph on a banked oval track. Distance, avg. speed, wattage recorded along with wind speed, direction, barometric pressure and temperature.
Data logged every 4 seconds and averaged over the run.

4 runs each between 1:30 and 2:30 @ 25mph, same track. Same data readings, but with wind from the Northwest at 115 degrees (wind on rider = 17.3 deg when running perpendicular to the wind). Weighted average created from a plot program I created to simulate yaw vs. time.

There was as much as 8 watts difference between the CarbonAero and Ouzo Pro Aero. I would put the Wolf right in between the BDC and Ouzo Pro Aero in terms of blade width/shape vs. crown width.

Chris

So I read this as saying with an H3 on the front and a Wolf fork it is actually a good set up given the fork options you tested. Does that sound correct? Any idea how that compares with 404 type wheel?

Worst to best, my friend. The Wolf is not a good fork to use with an H3.

With a 404 (or a HED Stinger 60) the order changes dramatically. For either of those wheels, the Reynolds is the fastest fork that I have tested.

Chris

 
Great! That's good stuff. Any chance you could also give us the spacing between the blades at the brake track? I think I recall you mentioning them before...

The question about running some of them with an equivalently deep wire spoked wheel is a good one. Wouldn't that help determine if what you're seeing is a result of some sort of interaction between the wheels and the forks, or just the aerodynamic properties of just the forks themselves? It would only take confirmation runs using forks from either end of the "spectrum", right?

Have you ever thought about more directly measuring the "power to spin" by mounting the fork and wheel in a vice and measuring the rate of spin decay both in the presence of a strong breeze (from a fan blowing at an angle) and without? To be honest, I have...and there's a reason I've been saving the blower fan from my old furnace...maybe this winter ;-)

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http://bikeblather.blogspot.com/

ah, got it - still working on reading and comprehension. The 404 type wheel being better than an H3, on a Wolf fork, is what I have read and understood to be correct. Thanks

Chris, thanks for the data. That is very interesting. I have P2C with Wolf TT forks and run Hed3 clinchers front and rear. They seem great to me! My training buddy is about exactly the same level cyclist as me. He has a P2C as well and when we train on standard training wheels we do about the same speed at about the same heart rate. However, when we time trial and he uses his Hed Stingers 90/60 and I use my HED3s , over various distances from 10-100km and in various weather conditions, he has never beaten me. Just anecdotal evidence I know!

I also noticed Brian Rhodes had H3s on his cervelo recently, they didn't hold him up :)

Hmm...so tell me, why doesn't that square with this (off of the Zipp site)...most notably, the H3 and 404 curves?:

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http://bikeblather.blogspot.com/

So then what is a good fork to use with the H3? Examples, please.

Thanks!

-- Boris

Any iteration of the Trek TT forks, or the current Quintana Roo forks both have the wider crown and leg spacing. As already mentioned the Blackwell Time Bandit and Kinesis Carbonaero should be good canidates. Finally, the Oval jetstream, though the vents are facing the wrong way, is a decent option due to wide spacing.

Chris,
Do you have any idea how the Cervelo Chord fork fits into your ranking? By my measure, it's ~36mm spacing at the brake track.

I hope you don't think I'm being critical about all this. As I said above, my main interest is because I've been contemplating picking up a set of H3s for general racing. I'm also trying to reconcile it with my own experience on my P2K with the Cervelo Chord fork. I found that my CdA was within .001 m^2 (i.e. ~= 1 watt difference at race speed) when using a Trispoke brand trispoke (VERY similar to an H3. Nearly identical rim depth and similar aspect ratios on the spokes) or a 404 front wheel. Both setups were tested with the exact same tire (VF Record 20c) and latex tube.

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http://bikeblather.blogspot.com/

IIRC, the Chord was just a rebadged Kinesis CarbonAero, which was the same as the Profile BDC.

The Cervelo Chord looks very similar to the CarbonAero from the side, but I don't know that it actually is a rebadged item if Tom is seeing a ~36mm blade separation at the brake track. The CarbonAero as used by QR is ~48mm there.
36mm is around my rememberance of the Profile BDC blade separation though. Perhaps there were multiple versions of the Chord?

Chris

More likely my recollection is incorrect. That is, I'm 99% certain that the Chord is the same as the BDC, which I thought was the same as the CarbonAero. If you say otherwise, though, I'll certainly take your word for it (especially since it would explain why you found differences between them...although Tom's data wouldn't seem to fit that scenario).

It's definitely not the same as the BDC that I had previously. That fork actually looks very similar to the newer Cervelo Wolf.

Chris

I would agree with that, especially since your reported weight of the BDC is ~200 grams heavier than what I measured on the Chord. From what I remember from from pics of BDCs, I think the profile fork legs are thicker.

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http://bikeblather.blogspot.com/

RE: your 1 watt difference between the 404 and HED3 - while that may not seem like much, you are indicating that in fact, the HED3 is performing poorly in that fork. All other things being equal (ie, not losing speed due to the pressure drag of the spokes), the H3 should be closer or equal to the performance of the 808, which would most likely get you more into the general area of my data.

Chris

Well...not exactly. For one, I don't have an H3, it's a TriSpoke, which is a slightly worse performer than an H3 according to the limited data I've seen. Second, when I said it was within .001 m^2 I was being generous...my calculated CdA for both configs was exactly .228 m^2. The "within .001" estimate was just my estimate of the precision of that calculation. Third, even Hed's own data on the H3 (which surprisingly show it worse performing than Zipp's data, go figure) doesn't show it to be as good a performer as an 808...I'm not saying it can't, because I've seen data that WITH THE RIGHT TIRE the H3 is pretty darn good. Lastly, my testing is basically at zero yaw and close to it. None of these wheels we're discussing perform dramatically differently at zero yaw.

Can you see why I'm slightly confused? :-)

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http://bikeblather.blogspot.com/