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Old 04-02-07, 10:21 PM   #1
DrWJODonnell
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Wind Tunnel Testing

Does anyone know of links/locations of low speed wind tunnels for testing cycling aerodyanamics?

I know there are tunnels in San diego, Seattle, Texas A&M, and MIT. I think there also may be one in VA. Does anyone know about costs or availability? Thanks for any info in advance.
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Old 04-02-07, 11:12 PM   #2
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I looked into the San Diego tunnel. They suggested getting in touch with an org that's doing group sessions.

$975 for your turn.

Near as I can tell it's around $5-7k a day, if you figure in the group's profit margin.

I'm still interested in doing a session, the last date they had was conflicted for me and they don't have any new dates up yet.

Here's the link:

http://www.multisports.com/windtunnel_camp.shtml
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Old 04-03-07, 09:33 AM   #3
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If anyone has an e-mail address for John Cobb, he could tell you everything you need to know about the Texas A&M wind tunnel. He did a lot of work there with LA in the 90's. Or try the search function on the Texas A&M site. It's www.tamu.edu.
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Old 04-09-07, 06:27 PM   #4
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I saw John today. His e-mail address is jcobb@blackwellresearch.com. Website is www.blackwellresearch.com. He can direct you to anyone at the Texas A&M tunnel in College Station.
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Old 04-09-07, 06:40 PM   #5
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Check out this forum...http://biketechreview.com/phpBB2/index.php
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Old 04-09-07, 08:53 PM   #6
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Quote:
Originally Posted by TSUTexan93
the Texas A&M tunnel in College Station.
Not to hijack the thread, but could we please get at least one Aggie joke out of this?
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Old 04-09-07, 10:37 PM   #7
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why would you ever spend so much on wind tunnel testing?
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Old 04-09-07, 10:44 PM   #8
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Quote:
Originally Posted by Walleye
Not to hijack the thread, but could we please get at least one Aggie joke out of this?

ok. here's one:

What is the difference between the Aggies and Rice Crispies?
Rice Crispies know what to do in a bowl.
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Old 04-09-07, 11:17 PM   #9
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Quote:
Originally Posted by bodaciousguy
why would you ever spend so much on wind tunnel testing?
Some people spend (myself included) $$$ for wheelsets that might get one a few extra seconds in a TT. Aerodynamic positioning relative to power is probably the best way to improve one's time. Oh, and it costs less than many wheelsets.

That is why.
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Old 04-10-07, 07:42 AM   #10
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Quote:
Originally Posted by DrWJODonnell
Some people spend (myself included) $$$ for wheelsets that might get one a few extra seconds in a TT. Aerodynamic positioning relative to power is probably the best way to improve one's time. Oh, and it costs less than many wheelsets.

That is why.

You are right that aero improvement will net much greater improvement than weight savings, but if you race criteriums or road race, you are going to be sitting in 99% of the time, even if you are in a break, you will only be at the front a very small fraction of the time. The only time it will help is when you are off the front alone. How aften does that happen.

If you only TT, then yes it makes sense to wind tunnel test, but its just not effective for road racing or criteriums. The pros only use it for their TT efforts.
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Old 04-10-07, 08:00 AM   #11
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Quote:
Originally Posted by San Rensho
You are right that aero improvement will net much greater improvement than weight savings, but if you race criteriums or road race, you are going to be sitting in 99% of the time, even if you are in a break, you will only be at the front a very small fraction of the time. The only time it will help is when you are off the front alone. How aften does that happen.

If you only TT, then yes it makes sense to wind tunnel test, but its just not effective for road racing or criteriums. The pros only use it for their TT efforts.
Are you serious?!?!?!?!?
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Old 04-10-07, 08:13 AM   #12
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Quote:
Originally Posted by DrWJODonnell
Some people spend (myself included) $$$ for wheelsets that might get one a few extra seconds in a TT. Aerodynamic positioning relative to power is probably the best way to improve one's time. Oh, and it costs less than many wheelsets.

That is why.
No it doesn't, you can spend $5000 a day in a wind tunnel.
you should read about David Millar's work in the wind tunnel, they spent tens of thousands getting him to optimize his position, but this actually slowed him down on the road. Once he dropped his wind tunnel position and went back to his old position, he won his next TT. Wind tunnels assume that the most aerodynamic position is all that needs to be optimized, but this ignores the mechanics of a rider.

Seriously, unless you are entering the Pro Tour and are optimizing to win a grand tour, wind tunnels will not make you any faster.
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Old 04-10-07, 08:15 AM   #13
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Quote:
Originally Posted by San Rensho
You are right that aero improvement will net much greater improvement than weight savings, but if you race criteriums or road race, you are going to be sitting in 99% of the time, even if you are in a break, you will only be at the front a very small fraction of the time. The only time it will help is when you are off the front alone. How aften does that happen.
Sounds like the opinion of a wheel sucker.
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Old 04-10-07, 08:25 AM   #14
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Quote:
Originally Posted by DocRay
Sounds like the opinion of a wheel sucker.

Ever heard of a little concept called a circular paceline? Probably not, so let me enlighten you.

Several guys, lets say ten, get off the front. The form a paceline that has two lines, one line moving up, the other moving back. At all times, everyone stays on someones wheel, except for the guy at the front, who is only in the wind for a couple of seconds. The whole idea is one massive wheel suck. Its the fastest way for a group of riders to travel.

Maybe you've seen this technique used? All pro road racers use it, so next time you watch a pro race, look for it, you may learn something and then be able to post something intelligent here, instead of your imbecilic comments.
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Old 04-10-07, 02:33 PM   #15
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Quote:
Originally Posted by DocRay

a) No it doesn't, you can spend $5000 a day in a wind tunnel.

b) you should read about David Millar's work in the wind tunnel, they spent tens of thousands getting him to optimize his position, but this actually slowed him down on the road.

c) Seriously, unless you are entering the Pro Tour and are optimizing to win a grand tour, wind tunnels will not make you any faster.
a) $975/day if you go with a group.

b) LSWT testing has improved a lot of pro's TT times, just because one guy is allergic to penicillin doesn't mean you shouldn't use it.

c) I don't believe that physics only apply to Pro Tour riders.
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Old 04-11-07, 12:33 AM   #16
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Quote:
Originally Posted by San Rensho
Ever heard of a little concept called a circular paceline? Probably not, so let me enlighten you.

Several guys, lets say ten, get off the front. The form a paceline that has two lines, one line moving up, the other moving back. At all times, everyone stays on someones wheel, except for the guy at the front, who is only in the wind for a couple of seconds. The whole idea is one massive wheel suck. Its the fastest way for a group of riders to travel.

Maybe you've seen this technique used? All pro road racers use it, so next time you watch a pro race, look for it, you may learn something and then be able to post something intelligent here, instead of your imbecilic comments.
Please stop, i'm embarassed for you. Do you really think people go to wind tunnels on their road bikes? He is talking about his TT bike which is (believe it or not) ONLY for solo time trials.
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Old 04-11-07, 05:42 AM   #17
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Please stop, i'm embarassed for you. Do you really think people go to wind tunnels on their road bikes? He is talking about his TT bike which is (believe it or not) ONLY for solo time trials.
+1 billyun
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Old 04-11-07, 06:05 AM   #18
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Quote:
Originally Posted by DrWJODonnell
Some people spend (myself included) $$$ for wheelsets that might get one a few extra seconds in a TT. Aerodynamic positioning relative to power is probably the best way to improve one's time. Oh, and it costs less than many wheelsets.

That is why.
Other than the pretty charts and graphs, what will a wind tunnel tell you at your level of development, that you can't find out doing coast downs on a good downhill on a windless day?
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Old 04-11-07, 06:31 AM   #19
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Originally Posted by NoRacer
Other than the pretty charts and graphs, what will a wind tunnel tell you at your level of development, that you can't find out doing coast downs on a good downhill on a windless day?
Oh for heaven's sake. You guys are ridiculous.

Dr. Will... Ignore this bunch and take these types of questions to the BikeTech Review forum. You will find what you're looking for there.

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Old 04-11-07, 06:39 AM   #20
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Quote:
Originally Posted by NoRacer
Other than the pretty charts and graphs, what will a wind tunnel tell you at your level of development, that you can't find out doing coast downs on a good downhill on a windless day?
Position changes varying wattage outputs for one... Coasting downhill will only help in working out one part of the equation. You can force yourself to ride in a very extreme position because it has shown the best figures during your roll down test but not how you maybe can only push out half the watts because your pedalling and breathing is impacted.

If we had a tunnel with the expertise here in Australia I would be booking a session in first thing tomorrow morning!
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Old 04-11-07, 06:42 AM   #21
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Quote:
Originally Posted by DocRay
Seriously, unless you are entering the Pro Tour and are optimizing to win a grand tour, wind tunnels will not make you any faster.
See my post above. This is ridiculous.

The purpose of the wind tunnel is to find the position on a time trial bike that results in the best tradeoff of aerodynamics and sustainable power output. The idea is to find out one's CdA in multiple positions and get an initial feel for power output at each position. This must be followed up with work on the road using a power meter to determine which position will actually acheive the sustainable speed sweet spot.

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Old 04-11-07, 07:32 AM   #22
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Hope the OP has lots of money:

Considerations for Data Quality and Uncertainty in Testing of Bicycle Aerodynamics By: Michael J. Flanagan, Ph.D.

Quote:
This concept of ergodicity requires that the data be stationary, specifically, that the data exhibit no time-dependence in any of the statistical moments. Figure 7 presents a plot that is representative of the RMS drag value (second statistical moment) versus time. For this particular run, 20 seconds of data were taken corresponding to approximately 10,000 data points. The result of this run is one "test point" - the average of all 10,000 data points for this run. The data exhibit a trend to converge to approximately 0.8 lb - the value is actually meaningless. The very fact that this plot shows ANY time dependence, as opposed to being a straight line, is VERY significant. This plot shows that the flowfield is NOT ergodic. Consequently, the entire data set is suspect from an accuracy standpoint. The concept of ergodicity requires, regardless of the particular ensemble (data set) analyzed, that there will be no time-dependence in the ensemble - that all test points will yield identical results. In order to achieve an accurate result, repeat runs would be necessary to achieve some type of ensemble average. This ensemble average would provide a more accurate estimation of the "true" drag level. How many repeat runs are necessary for this one test point? The only way to know for sure would be to make perhaps a dozen or more and plot the average value from those runs.

One can now understand the problem encountered. If our original test matrix involved several model configurations at several velocities, 100 test points could be involved - say five days of testing at $4000/day. Now, if we are required to repeat each test point 10-15 times to achieve our desired accuracy goals, we now need 50-75 days and $300,000.


CONCLUSIONS
The most significant trends apparent within the test data are the dynamic influence of wheel rotation and the rider pedaling. Additionally, the effect of subtle changes in body position during the run is significant. While the dynamic trends are of interest, the most useful information to the rider is some type of accurate, time-averaged drag value. Accurate time-averaging, however, does require the assumption of flowfield ergodicity. As the flowfield surrounding the cycle and rider within the wind tunnel is clearly NOT ergodic, "real" drag values are meaningless for short-duration testing. In order to achieve meaningful drag levels, the test plan must allow for sufficient repeat runs for each test point. What are the reasonable limits to data quality? For this test, the customer wished to know drag levels to 0.06 lb or approximately the predicted measurement uncertainty level. This was not possible after the fact, as the flowfield was clearly not ergodic and the test plan and funding did not allow for any additional testing. Some of the information obtained was useful. In particular, specific effects during a given run, such as the effect of head-up versus head-down, provided a repeatable increment from run to run. So, even though the absolute level of the drag was never determined, a highly accurate measurement could be made of the effect of handlebar droop, head-up versus head-down, and pedaling versus stationary. In addition, as the effect of pedaling was the primary reason the flowfield was not ergodic, all data taken while the rider was stationary data were valid.
For this particular technique, the sources for uncertainty are neither the instrumentation nor the data acquisition system. Rather, the close-coupled nature of the balance and test vehicle system creates a flowfield environment that is not ergodic. The presence of the rider and the dynamics due to the pedaling required to achieve proper flowfield simulation force the assumption of ergodicity to be invalid. This raises serious doubt about the certainty of the measured drag levels. Only through repetition of one particular test condition will sufficient data be available for an ensemble average. This will provide a more accurate estimation of the "true" drag level.
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Old 04-11-07, 09:29 AM   #23
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"Reproduced from: Cycling Science Fall '96" I didn't read the article, but I know 11 years is a long time in terms of technical progress.
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Old 04-11-07, 09:40 AM   #24
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Quote:
Originally Posted by zimbo
See my post above. This is ridiculous.

The purpose of the wind tunnel is to find the position on a time trial bike that results in the best tradeoff of aerodynamics and sustainable power output. The idea is to find out one's CdA in multiple positions and get an initial feel for power output at each position. This must be followed up with work on the road using a power meter to determine which position will actually acheive the sustainable speed sweet spot.

--Steve
+1 See my post above as well with a link to the Biketech review forum.
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Old 04-11-07, 09:59 AM   #25
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"Reproduced from: Cycling Science Fall '96" I didn't read the article, but I know 11 years is a long time in terms of technical progress.
True. And, the cost of living has dropped in 11 years, too. I'm sure you'll get a lot more charts and graphs for $300,000.
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