Position first, equipment second. Since we had the Morf-Tech only half-tightend it was easy to raise and lower the arms as we went a long to do some dynamical testing before we got set in a postition for the 1-min average reading. Very effective in my view.

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Apparantly Kask Mistral and LG 9 performed nearly equivalent for your position.

Endura and BioRacer trisuit performed also equivalent ?

In both lateral view pictures you posted, your humerus is vertical. Personally I prefer much more pad reach, feel more comfortable and powerful. This verticality could be the reason for full mantis feeling horrible.

Nothing to see here... 😉

We (MORF) are working on some BTA concepts that more cleanly integrate and manage airflow around the bike with rider in ways that are possible when no base bar is present. Allan was kind enough to run one of our prototypes designed for more radical bar angles. Much work to do still, but it looks promising👍. Thanks Allan!!!

Thanks,
Frank

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Thanks,
Frank

http://www.morf-tech.com

What was the watt difference between the P-09 and the sworks helmet? Was there anything about the sworks that seemed "flawed" or is it just a rider dependant, fit result?

2 watts slower than the P-09. Nothing flawed with the sworks

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These are the same shot correct? Because the side profile makes your back look a lot, lot flatter than the frontal. Not sure I like the camera level on that front shot, but then it's not my tunnel. ;)

Also, I think some have danced around it, but no one is really questioning the 0.175? Even at 5º that sounds really really low. I believe that's what the tunnel spit out, but would that be the same number in (or even close) in A2 or San Diego?

For comparison, I am very small and even at 10º I don't sniff 0.180 let alone 0.175. I am also pretty darn efficient being able to average 25.4mph on 193ish watts.

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Hello

Apparently you consider that increasing yaw improve CdA ?
How is CdA calculated at yaw ?
Taking into account "relative longitudinal wind" vs "longitudinal drag" ?
Or ignoring reduction of "relative longitudinal wind" ?

in frame/wheel yaw testing, graph show drag reduced at small yaw (compare to no yaw), but only because "relative longitudinal wind" is reduced. So "longitudinal drag" goes down also. Does not mean CdA is lower.

Everything I have ever seen shows lower CdA m^2 at say 10º vs 0º. This includes my own trip to A2. Subjectively, I'd rather be riding into any direction wind vs that of a dead on head wind.

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In a wind tunnel, when increasing yaw to 90° :
"relative longitudinal wind" goes to zero progressively
so "longitudinal drag" goes down to zero progressively (in grams)

This does not mean that CdA goes to zero.

In a longitudinal flow at 30mph (i.e bike riding 30mph with no wind), bike + rider at given x CdA, drag is y grams
if you add 5mph lateral wind (so resulting wind is 30.5 mph at some yaw)
not sure the lateral wind will improve efficiency of existing system
not sure new drag y2 will be lower than y

In most cases I have seen (cars), y2 is higher than y
Lateral wind perturbate aero efficiency and increase CdA.

This is why I ask the question when I see the opposite

Is CdA really calculated with longitudinal flow, or total flow, and in this second case, it is not realistic. Useful for comparison at same yaw, but how to compare a .17 at 10° yaw and a .18 at zero yaw ?

Let me back up.....you're saying I shouldn't compare the OP's 5° numbers with mine at 0° or 10°?

Really that is what I was doing. Forget that tunnel numbers go down as one sweeps out or anything else. Also, no one suggested CdA goes down to zero.

Also, why would one add in wind? We are not adding in wind when sweeping in a tunnel correct? What we are saying is that to hold 30mph at this new angle of attack we would need less watts; therefore, ones CdA reads out lower. Is this not the correct interpretation? i.e. in this new direction of attack our shape is more efficient than head on into the wind.

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No. When you are at 0 deg then it's analogous to riding 30mph with no wind. Or sitting still with a 30 mph headwind. If you turn the table to 10 deg then it's analogous to a *resulting* wind vector of 30 mph and 10 deg. If you had a 90 deg crosswind that gave you that result, you'd be traveling at less than 30 mph. It is *not* riding at 30 mph with a crosswind.

Right. I'm terrible at explaining myself. Maybe an example?

25mph ground speed 5mph wind. At 0° you need X watts to hold your 25mph ground speed.

Turn away from the wind at 5° and now you need Y watts to hold your 25mph ground speed.

X>Y

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At Y you have less headwind, so of course that will be easier. But that isn't what is measured in the tunnel. There is no ground speed, only wind and direction.

Understood. But how did we even get on this tangent.

I asked how that number (0.175) might stack up if the OP tested in A2 or San Diego. I should have never given my own numbers for comparison. Gotta love forums. 🙄

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If you are sponsored by LG, you could try these. I have a set and like them. Signature 84. They were a little heavier, more substantial feeling (upper was less flexy), and a little wider and roomier in the toe than the Giro Empires I also tried. If you aren't sponsored, they are cheap ;)

Think of it this way....

If windspeed is 25mph then

Wind at zero yaw is = 25*COS(0) = 25*1 = 25
Apparent Wind at 5deg Yaw is = 25*COS(5) = 25*0.9962 = 24.90

So the cda (at this low yaw angle)is the same but wind speed is lower....

I imagine that the System(bike and rider) cda actually goes up due to other factors at yaw like the system(bike and rider) gets wider..

Thanks for the info. What position was this and what suit? Also, if you could show detail (CdA for each) I'd appreciate it.

 
I made some search to see if CdA of same rider with different yaw was available.

Because it make sense to test at some yaw. In real life, in most case some wind not in the same direction as we are, so 5° yaw is probably more realistic than 0° yaw.
At least for a triathlete, not a pursuiter.

And all comparisons at same yaw make sense.
I mean, if Mistral is 2w faster than S-Works at 30mph 5°yaw, will be same on the road.
If this suit faster than this one at 5° yaw, will be same on the road.

But my question was : is 5° yaw deliver better or worse CdA than 0° yaw ?
Just to know.
And especially, can I compare Allan very low CdA to other CdA at 0°yaw, or calculated from real conditions ?

So, find this :

https://www.researchgate.net/...n_Experimental_Study

Interesting research done at 0, 15, 30, 45° ... until 90°.
Worst CdA is at 15°, but :
not a lot of granularity in measurements
CdA increase much at 15° if torso is higher, not as much if torso is lower

And also this :

https://forum.slowtwitch.com/...da_target_P5496638-5

Graph from Andrew Coggan (page 5) show that :
for Superman position, CdA increase at yaw (5 and 10°)
while
for classic aero position, CdA decrease at yaw (5, 10 and 15°)

OK, so conclusion is..... it depend....

Most probably Allan CdA at 5° yaw is probably very similar to his CdA a 0° yaw.
Slightly higher or lower... don't know.


Side note : was also very surprised to see for "bike only measurements" some drag graph (not CdA graph, but drag in grams) lowering at yaw, some other going up at yaw... strange.

I am not sponsored by TorHans, the VR was the fastest option I tested on the frame, although I drilled my own holes in the bracket so it sits lower than it would otherwise. In fairness, I did not drill out the Xlab that I tested as it was slower in the baseline position than the VR in the baseline position so I had already decided that I was going with that option (I wanted to be able to return the items I wasn't going to use!). The VR was negative drag, so for 70.3s I race with the bottle on the frame even though I typically don't fill it. The angle on the bottle I have behind my seat was the biggest savings I found. Once Jim helped me get the angle correct, it was a very nice drop in cda. The AeroZ was the only BTA set up that I tested that was net zero, everything else I tested at the time was positive drag for BTA options.

I have changed my head/hand position significantly over the last year and am going over to the Boardman center in the UK to test out again this January. Looking forward to seeing where I can make fast faster as well. FWIW, the average CdA for the all but one of the races I did this year were under .23 with one of them being under .22.

Very minor but the stock thru axles can be swapped out for Maxle Stealths for less frontal area and lighter weight.

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Thanks a lot for your reply. I really appreciate it. I will go for a TorHans VR.

Did you test the xlab on seat tube and down tube? do you know what position which is best? I have a race on Sunday and not time to get a new solution by then.

Will be very exiting to see your results in the tunnel.

BTW, congrats on you Hawaii slot :D

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I apologize for my lack of response, but I had a lot that absolutely needed to be done (like getting my bike in actual riding condition) before traveling one month to Patagonia and the Patagonman.

I said I would share everything and be transparent so here is my full results from the wind tunnel: https://www.dropbox.com/...3y3fXe4y2THpYia?dl=0 (UPDATED WITH A WORKING LINK)

The "Allan Hovda Aerofit 21 November" is the numbers and the data and the file below contains all the pictures from the test. If anything was unclear just ask.

Btw, if anyone wonders why I tested the Castelli Gabba jacket vs Santini Beta it is the options I have for Norseman where you need warmer clothing.

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I really appreciate you sharing your info!

The link has a problem though: "Unable to retrieve file: The path is incorrect, or the public link has expired"

I am in the process of changing my transparent round gel bottle on the downtube to an aero bottle. After reading this interesting thread I got aware of the xlab aero tt. However, the Torhans VR seems more aero.

2 questions:
-how do you purchase the torhans in Europe?
-how is the holder of the torhans? (I heard some aero holders are insecure at vibrations and the xlab seems to be very stable)

I've been running the Felt version on my Da since it's inception (had a teammate that hated it and gifted it to me). I've done maybe 20-30 Time Trials with it varying road conditions from perfect to horrible) and at least 1000 miles one the road (~300 of which were on Minneapolis's crappy roads). I've always had my doubts about bottle security with the VR so I always pull it when traveling with the bike on the rack. That being said, when I loaned the VR to Kiley for his shootout and specifically tell him to pull it from the cage when he drives home he forgets....he makes it from Mooresville NC to Philly without losing the bottle, though. I've also found me some nasty potholes that have launched BTS bottles and knocked me out of my pads, but yet the VR holds firm.

I doubt i'll be driving with the VR in the holder any time soon, but my doubts about losing the bottle during a ride/race all disappeared a long time ago. It's not even a thought anymore.

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