Aero data from 19 wheels by Hambini

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AJS914
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by AJS914

The HED Jet 6 is within 2 or 3 watts of most other 60-65mm rims on the chart. That, I guess, is within the margin of error. And the HED wheelset only costs $1000 so it could still be a great choice for triathletes.

tanhalt
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by tanhalt

AJS914 wrote:
Mon Oct 29, 2018 5:46 pm
The HED Jet 6 is within 2 or 3 watts of most other 60-65mm rims on the chart. That, I guess, is within the margin of error. And the HED wheelset only costs $1000 so it could still be a great choice for triathletes.
Well...the stated "experimental error" is +/-2.5%, so more like +/- 4.6"watts" on that arbitrary scale...so yeah, it's pretty hard to say one wheel or the other is any different on almost the entire list :noidea:

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guyc
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by guyc

Buy the ones you like the look of the most. We ain’t pro, bro.

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otoman
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by otoman

Thanks for posting the HED's! I have almost have bought those numerous times over the years...
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C36
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by C36

tanhalt wrote:
AJS914 wrote:
Mon Oct 29, 2018 5:46 pm
The HED Jet 6 is within 2 or 3 watts of most other 60-65mm rims on the chart. That, I guess, is within the margin of error. And the HED wheelset only costs $1000 so it could still be a great choice for triathletes.
Well...the stated "experimental error" is +/-2.5%, so more like +/- 4.6"watts" on that arbitrary scale...so yeah, it's pretty hard to say one wheel or the other is any different on almost the entire list :noidea:
If I understand properly that’s “accuracy”, not “repeatability”. 2.5% accuracy it’s how far away are you from “the exact value” (each measuring tool has an accuracy in his specs), repeatability how far away from each other are subsequent measurements.
Image

We don’t “care” about accuracy (if all the wheels are 5 or 10W off compared to “exact value”), we do care or repeatability of the measurement.

Ultimately improving accuracy is very tough (require higher technology or complete different measurement system), repeatability quite easy multiplying the measurements.


If I misunderstood, please correct me


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hambini
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by hambini

The repeatability of this test is high and it is built into the way the testing is carried out. The measurements are repeated several times but it may not look like it from the graphs.

The main error comes from instrumentation measurements but this is in effect the same for every wheel. So the number is relative. ie if one wheel is 195W and another is 200W. The error might be 2.5% but the relative difference (5W) between the wheels would still stay the same.

Some individuals think the error bars overlap but you can't take the max of one and the min of another as justification. The error bars are more like a normal distribution so it gets less likely towards the extremities.

Hope that helps
Hambini Aeronautical Engineer, Polluting YouTube since 2016 - views expressed are my own...
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tanhalt
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by tanhalt

C36 wrote:
Mon Oct 29, 2018 7:58 pm
tanhalt wrote:
AJS914 wrote:
Mon Oct 29, 2018 5:46 pm
The HED Jet 6 is within 2 or 3 watts of most other 60-65mm rims on the chart. That, I guess, is within the margin of error. And the HED wheelset only costs $1000 so it could still be a great choice for triathletes.
Well...the stated "experimental error" is +/-2.5%, so more like +/- 4.6"watts" on that arbitrary scale...so yeah, it's pretty hard to say one wheel or the other is any different on almost the entire list :noidea:
If I understand properly that’s “accuracy”, not “repeatability”. 2.5% accuracy it’s how far away are you from “the exact value” (each measuring tool has an accuracy in his specs), repeatability how far away from each other are subsequent measurements.
Image

We don’t “care” about accuracy (if all the wheels are 5 or 10W off compared to “exact value”), we do care or repeatability of the measurement.

Ultimately improving accuracy is very tough (require higher technology or complete different measurement system), repeatability quite easy multiplying the measurements.


If I misunderstood, please correct me
That's a question for the data publisher to answer. In his blog post, it only says:

"The MAXIMUM EXPERIMENTAL ERROR has been calculated at +/- 2.5%, the middle of the range is plotted for each of the values to maintain consistency"

I interpret that to mean that each of the values in the chart shown have error bars (measurement uncertainty) above and below them of +/-2.5%...which makes for quite a lot overlapping uncertainty ranges between most of those wheels. In other words, it's more a measure of the repeatability.

I'd also like to point out that there's a note of the rider position being with +/-10mm. That can be concerning as well. I know from my own aerodynamic position testing that sometimes a change of 5mm or less in bar height can result in a dramatic increase or decrease in drag. I'm not saying it always does...just that at some points, that minor of a change can have disproportionate drag effects.

spartacus
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by spartacus

Hmmm. I was - and still am I suppose - considering the hed jet 6+ but it’s a little disappointing that they aren’t faster than the other 50mm wheels.

spartacus
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by spartacus

AJS914 wrote:
Mon Oct 29, 2018 5:46 pm
The HED Jet 6 is within 2 or 3 watts of most other 60-65mm rims on the chart. That, I guess, is within the margin of error. And the HED wheelset only costs $1000 so it could still be a great choice for triathletes.
Why do people always say they’re a good choice for triathletes specifically? Is there something about them that makes them less suitable for road riding? If anything it seems like the aluminum braking surface would make them preferable for road cycling.

tanhalt
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by tanhalt

spartacus wrote:
Mon Oct 29, 2018 8:44 pm
Hmmm. I was - and still am I suppose - considering the hed jet 6+ but it’s a little disappointing that they aren’t faster than the other 50mm wheels.
Personally...I wouldn't take this "testing" to mean that they are (or aren't)...too many unknowns, starting with the input data acquisition.
Last edited by tanhalt on Mon Oct 29, 2018 8:55 pm, edited 2 times in total.

tanhalt
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by tanhalt

spartacus wrote:
Mon Oct 29, 2018 8:46 pm
AJS914 wrote:
Mon Oct 29, 2018 5:46 pm
The HED Jet 6 is within 2 or 3 watts of most other 60-65mm rims on the chart. That, I guess, is within the margin of error. And the HED wheelset only costs $1000 so it could still be a great choice for triathletes.
Why do people always say they’re a good choice for triathletes specifically? Is there something about them that makes them less suitable for road riding? If anything it seems like the aluminum braking surface would make them preferable for road cycling.
They are perfectly suitable for road riding. They are within a handful of grams of the mass of equivalently performing all-carbon clincher wheels, and as you point out, the aluminum braking surface outperforms braking on carbon...especially if you go with one of their models that has the "Turbine" brake track treatement (basically engraved radial grooves w/black anodizing). Coupled with a quality brake, they equal, or outperform disc brakes, even in the wet.

You just have to get over the stereotype that the hybrid aluminum/carbon construction is "cheap". It's actually a better solution to the "aerodynamics plus good braking" problem than so-called "high tech" all-carbon clinchers, rim OR disc braked.

Of course, now I'll probably be accused of being a "shill" for Hed :roll: (which if you are aware of any of my history with interactions with them you migh find quite laughable).

AJS914
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by AJS914

I only said triathalon because they seem to be popular with triathetes. Looking at them, they do weight 1700 grams so they are more than a handful of grams heavier than say a Campy Bora One 50mm (1485 grams) but they are also around $600 cheaper.

hambini
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by hambini

tanhalt wrote:
Mon Oct 29, 2018 8:54 pm


Of course, now I'll probably be accused of being a "shill" for Hed :roll: (which if you are aware of any of my history with interactions with them you migh find quite laughable).
Well in England, we'd call you a chancer who talks a good game. Because you are not familiar with "British English" in the purest form - I will elaborate for your benefit and the amusement of fellow forum members.

Someone who talks a good game is an individual who acts like they know a lot about a subject (in this case aerodynamics), has all the right "buzz words" and talks like they are a professor when they are simply a spec of $hite on the anus of humanity and when put under the microscope, they have the same knowledge as that of an amoeba.
Hambini Aeronautical Engineer, Polluting YouTube since 2016 - views expressed are my own...
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tanhalt
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by tanhalt

hambini wrote:
Mon Oct 29, 2018 9:41 pm
tanhalt wrote:
Mon Oct 29, 2018 8:54 pm


Of course, now I'll probably be accused of being a "shill" for Hed :roll: (which if you are aware of any of my history with interactions with them you migh find quite laughable).
Well in England, we'd call you a chancer who talks a good game. Because you are not familiar with "British English" in the purest form - I will elaborate for your benefit and the amusement of fellow forum members.

Someone who talks a good game is an individual who acts like they know a lot about a subject (in this case aerodynamics), has all the right "buzz words" and talks like they are a professor when they are simply a spec of $hite on the anus of humanity and when put under the microscope, they have the same knowledge as that of an amoeba.
I just wanted to quote that in case you decide to edit it out later. For posterity, if you will...

BTW, do you talk to your mother with that mouth?

Now then...to get back to the subject at hand instead of constantly responding to your ad hominem attacks and diversions...you said that the data points reported are the midpoint of the ranges. Also, are you saying the +/-2.5% represents the spread of the data, and not the calculated sample variance?

As you should well know, the standard method of reporting experimental values is to report the mean (not the midpoint of the range of data) along with the calculated sample variance (not just the high and low of measured data). If that's the case, then the +/-2.5% represents an estimate of only 68.27% of the population estimate...so, overlapping ranges of those values means a much different thing than what you stated above (i.e. unlikely at the "tails").

I'm starting to think you created a test that really only tells us roughly how deep a wheel is...not necessarily how it will perform in real life. And measuring wheel depth can certainly be accomplished with much simpler methods...like a ruler, perhaps?

Marin
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by Marin

Wow what an. So sad.

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