I would also like to learn more about your findings in regards to aero helmets. I am wanting one for next year and am very interested in the Rudy Syton Open. Any thoughts on this helmet from MIT or anyone else.

Do you happen to have a link to the MIT podcast you reference in your post?

Yes. Sorry about that. I guess I should have included it in the original thread.

http://www.triathletemag.com/...dcast_Dec19_2006.mp3

It was very interesting to listen to this.

Bento Box more aero. Who would have thought it.

The Triathlete Magazine website seems down for now. I've mirrored the podcast here.

And yeah, I just started working with Mark in the wind tunnel last term. You can find a few pics of some of the MIT cycling team cyclists in their TT positions on the MIT cycling team website. http://www.mitcycling.org/Roster/2007/index.shtml (shameless plug for MIT cycling. q=) Check out Mark Cote and Jason Sears in their Cervelos (and me in my Giant; I just switched to a Cervelo too though). You might have to scroll to get more pics.

- Guo-Liang
chewgl@mit.edu

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___________________________
Chewie
Slowtwitch Aeroweenie since '06

On helmets, there isn't a universally good helmet for everyone. How good a helmet is for you really depends on how you sit on the bike; I have a rather flat back, and my LG Prologue helmet serves me well enough. Mark TTs with a "lumpy" back (a la Lance Armstrong), and the new Specialized helmet seems to work well for him.

Furthermore, how much of an impact a helmet has on your aerodynamics also depends on how big you are (relative to the helmet) too. Helmets work in two ways: they either get the air off your back (those with tails that stick out and up, like the LG Prologue), or help the air flow in a streamlined fashion on your back (those that blend into your back). Both work, but work to different degrees for different sized riders. We haven't quantified that yet, and might be doing more of that in the spring.

As for bento boxes, the air behind the stem is an aerodynamically messy place; I should think adding a bento box helps smooth the air somewhat. Mark's bottle works on the same principle, by having something just behind the stem to smoothen the air, whilst serving as a reservoir for fluids too.

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___________________________
Chewie
Slowtwitch Aeroweenie since '06

Thanks for the link. What is up with the pic of the guy with his glasses upside down at the top of the MIT website? Upside down glasses must be more aerodynamic if an MIT student is doing it.

I really like the Rudy Syton Open and have been looking for one for a while. Hard to get locally for some reason. I liked the pod cast and what was said about the age grouper still benefitting from using an aero helmet and after thinking about it for a long while, will pull the plug and get one this season. 4 times more aero than a standard helmet is worth $200 to me. Already have race wheels and everything that I could want for my bike so the last thing is an aero helmet and a lot more training. I think they mention that even tilting the back of the helmet up helped is some cases.

I still would love to see the custom aerobars from MIT and what was done to them.

After listening to the podcast, it made me think about the un-aeroness of my shift cables coming out from the sides of my Shimano Ultegra STI's mounted on my Soloist.

I wonder what kind of drag these shift cables are producing? Compared to Campy Ergo levers...or Sram Force.

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I wonder what the drag numbers are for the Shimano shifters with Nokon's VS. standard cables. I just installed my Nokon's on my winter bike first to see how hard/easy it was to install them. Very simple and I am not sure why so many people say it is hard. Anyways, I would love to see the difference in Shimano normal, Shimano Nokon's, Campy Ergo and Sram. Would be interesting.

And related to that how about the drag of conventional cork-like bar tape with something like Benotto or the smooth carbon type bar tape?

If you added up all these small gains, I wonder what kind of time savings you could come up with?

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I was fortunate enough to be the one who interviewed Mark and produced the MIT wind tunnel podcast for Triathlete Magazine. Sorry I am a few days late contributing, but I thought I could answer some of the questions based on my time with Mark Cote at the tunnel. I had over 3 hours of audio I had to try and get down to 20 minutes, and there was lots more discussion on the very questions you have asked.

First, chewgl's comments on aero helmets in this thread are right on. Very perceptive.

On Mark's water bottle design, no pictures yet, but imagine a thin tapered cucumber.

Bento box! I saw the data with my own eyes. Cylinders are very, very bad, and the Bento box breaks up that cylinder. Mark's water bottle on the top tube does it even better.

On the cables question in the thread, yes, exposed cables, being cylinders, will increase drag significantly.

I will be taking the "unpublished" interview audio with Mark that covers some other facinating topics and put them in my podcast sometime this summer.

---

David Warden
Tri Talk Triathlon Podcast
http://www.tri-talk.com

@TriTalk: Summer?! Awww man youre killing me. Good podcast, cant wait to hear more.

Yeah I ended up picking up some Campy Record Ergo's for a good price and will now have the cables under the bar tape. Which will yield some very small drag decrease.

Also, Im working on a set of TT cranks a lot like Basso's last year.

As well as further tweaks to my aero position. I've found that doing yoga has really helped me to loosen up so that im able to get lower and more flexible on the bike.

jeremy

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Why not just zip tie an Arundel Chrono bottle to the top tube behind the stem?

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Thanks for the update. I would love to hear more information in the future to your interview. I was thinking that since I am re-installing my cables with Nokon's that I will take a lot more care with them around the aerobar area and try to hide the housings as much as possible. The Hed Cliplites do not have internal cable routing but I can make that happen for the most part by drilling out the extensions to hide the housings.

As for the bento box, I have to eat a bit of crow with a friend as I have been bugging him for a year about his "lunch kit" on his bike. I am now thinking that I will use a bento box for storing my tube, CO2 and levers when racing. Every little bit of aerodynamics will help right.

The other questions that I have is in regards to the way that you have your stem. I run my level with 3 spacers and I have been thinking to have the stem angeled and remove 1 spacer. It will put the basebar in the exact same place but I wonder if one or the other is better.

Aero Helmet is on the way once I find a place locally to get a Rudy Syton Open. I like the simple design and look of this helmet. I might order one but my hat size is 38cm so I am right on the border of the S/M and L. I think that the small would still fit and I have to try one on.

Keep us updated as I would not mind listening to all of the audio that you have. I could listen to it on my long runs or on some rides.

I can't belive no one's mentioned Mark's "trimming the straw on your aero bottle" comment from the podcast. If you haven't listened to the podcast, that info alone was worth it. A classic.

Or use integrated VisionTechs with the aero stem?

I like how he says wearing gloves will slow you done. cover all your bases.

I do not wear gloves while racing anyways. Just a waste of time to put them on.

fastening it there will not give me the aero advantages that you get when it is behind your stem.

Depends on if you could find a wedge shaped bag that would fill the gap between your seatpost and the rear-bottle holder. I haven't personally seen anything, but I haven't looked for that specific size/style, so they could definitely be out there.

Chris

The Hooker stem (or integrated aerobars) was even better.

Any pictures of the Hooker stem, Andrew?

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I wonder if the Bento Box measurements were taken with a rider onboard?

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cheaper to cut an airfoil shape out of styrofoam and tape it to your top tube behind your stem. Or, put one of the vision aero headset spacers behind the stem, and fill the space in between with plasticine.

Both of those methods would classify as fairings.

so is a wheelcover.. i don't think it's illegal in triathlon.

Perhaps not; I'm not au fait with triathlon rules on this.

I've also heard of one of the British cyclists competing in UCI track events with a sawed-off section of trispoke taped behind his stem to smooth the airflow, which somehow the commissaires didn't pick up on.

Wheel covers are an exception to the "fairing" rule because they duplicate a disk, but not quite as well. Adding anything non-structura to the bike like that would be considered a fairing, and thus illegal.

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Some are born to move the world to live their fantasies...

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Check out Biketechreview.com to see how a wheelcover relates to a disk...

Also, im thinking of making a carbon fairing that a Profile Upfront bottle sits in that takes the air off of the Profile and brings it right up to the headtube. Making that front area/bottle more disc like.

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here's a link to Dan's Hooker article w/ pics of my old bike, including shots of the stem.
http://www.slowtwitch.com/.../hookers/hooker.html

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________________________________________________________________________
"that which does not destroy me will only make me stronger" Frederick Nietzsche
andrew peabody
http://BREAKAWAYMULTISPORT.COM

actually wheelcovers are considered fairings because they are not allowed in UCI-conformant TTs. You probably don't worry about this because in the USA you guys don't follow those rules yet, as i understand it.

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I would think that they fairing would have to be longer (bento box size) than the fairings shown in the Hooker thread. Also I would bet money that they fairing used to hold the water on the top tube mentioned in the MIT pod cast would be at least half the length of the top tube. I guess we will not know until we actually see it.

Some new information:

From this article:

http://www.velonews.com/tech/report/articles/11504.0.html


Kim Blair, director of the MIT wind tunnel offered a presentation on aerodynamic research with bikes. He talked about drag and boundary layers and airflow, followed by how tunnel testing is accomplished at MIT and at other tunnels. When he got to the results section, many in the audience were taken aback by a water-bottle design from MIT graduate student, purportedly able to save 110 seconds over the course of a 40 kilometer time trial.

Now if only we could see this thing and get one.

What about the water bottle that FLoyd Landis used in the final TT stage of the TDF last year?, it looked pretty aerodynamic to me.....

110 seconds???? Over a 40k???

I know. That is a huge claim. That is why I really want to see this thing and why it would save this much time. From what I have heard, it helps with the flow behind the stem. So if this was the case them why not design the top tube of the bike to actually come up behind the stem and run back to the seattube. I know that other companies have done oval and aero top tubes but maybe after this information they can do it correctly.

What about this?

The think the ratio is still wrong. I would think that it would have to be about a 3:1 ratio and this is not even close. The concept is good but I would guess that the reason the new water bottle tests so well that it would make a round tube that is 1:1 become more like a 3:1. Just a guess.

Have an oval top tube that is around 70 -75mm tall and 25mm in width (just an example) but with the headset mounting near the bottle of the tube and have the other 2/3 of the top tube just behind the stem and run it back to the seat tube. Intergrated seat clamp and you would have a very smooth transition.

The issue with almost every aero top tube is that they mount the headset at the top of the top tube and not at the bottom to use the top tube as a fairing.

Maybe the new Cervelo P4C (hint hint) can have an aere top tube that flairs up right behind the stem and run back to create the most aero Cervelo ever.

How about incorporating a hydration bladder into the top tube to hold about 750ml.

yeah, almost 2 mins is crazy.

I start to get worried when a scientist becomes a capitalist. The concern is that they will massage the science data to support the capitalist revenue.

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@ TriTalk----how long was the thin tapered cucumber?

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i will take a photo of mine tonight for ya....


g

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greg
www.wattagetraining.com

I recall the water bottle being about 1/3 the length of the top tube.

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David Warden
Tri Talk Triathlon Podcast
http://www.tri-talk.com

Did it start right behind the stem just leaving enough room to turn the stem and then head back about 1/3. Also was it thicker than the top tube and if so how much. I am so very curious about this and if the claim of 110 seconds is accurate.

"The most surprising thing about aerodynamic gear? A goofy-looking aero water bottle prototype designed by an MIT grad student saved almost as much as the wind tunnel session. It looks like a bedpan on a top tube, but it works."


http://boulderreport.bicycling.com/...attack_of_the_e.html

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" -In examining the aerodynamic benefit of various factors, Blair’s team found that expensive aerodynamic wheels save only 40 seconds over a 40km individual time trial. An aerodynamic rider position saved over two minutes. Granted, the most aero position will come via a $1,000/hour wind tunnel session, but if you’re really interested in it, you can start by experimenting with your position on a long, level stretch of road with a powermeter. The most surprising thing about aerodynamic gear? A goofy-looking aero water bottle prototype designed by an MIT grad student saved almost as much as the wind tunnel session. It looks like a bedpan on a top tube, but it works."


So, let's see... I can save almost two minutes, but I have to drink out of a bedpan. Hmm....

Steve

---

Steve

"If you ain't first, you're last." Reese Bobby Talladega Nights

...and we're STILL waiting to see just what this thing looks like. Any pics out there? anyone? Buhler?

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________________________________________________________________________
"that which does not destroy me will only make me stronger" Frederick Nietzsche
andrew peabody
http://BREAKAWAYMULTISPORT.COM

Is it really a water bottle or a fairing that holds water?

Bman,
I recall that it could be mounted anywhere along on the top tube, but right behind the stem would be the best place to realize the aerodynamic advantages of changing the stem from a cylinder to a wing. I'm confident that it did not obstruct the stem in any way, and it was thicker than the top tube by a few centimeters on each side. Also, I believe that the claim of 110 seconds over a 40K time trial was not due to the water bottle alone, but due to all of the adjustments to bike, equipment and rider, of which the new water bottle was a component. The data I saw verified that the water bottle prototype was one of the most aerodynamic water bottles tested.

---

David Warden
Tri Talk Triathlon Podcast
http://www.tri-talk.com

Typical reporting some days. They always seem to leave out some information. I am glad that you cleared some of this up for us. I would love to see more information in regards to the whole bike set up and them maybe break it down into individual aspects of time savings. Most to least.

I sure hope someone from MIT would take the time to type up a report for the thread. Just wishful thinking.

I've got a plan for this that I think will equal or better anything available anywhere. It involves creating a plasic/rubber bladder about 1 1/14" wide and 3 to 4" tall the length of my top tube and enclosing it in spandex/neoprene between the stem and seatpost. Still working on where I will get the bladder...hopefully there is a think model camelback or other similar brand.

Chris

If you guys would like, I can Email MIT Cycling and ask them to post up.... let me know.

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"Pace is just a matter of having enough RedBull..." -Rappstar

Hey if you can do that, that would be great. The more info and pics the better. It is very interesting stuff coming from those guys.

im going to try and make my own, by making a carbon fairing and putting a small water bottle inside of it.

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Alright.
I sent am email out to the MIT team. Hopefully they'll give me a shout back and I'll let them know about this thread.

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"Pace is just a matter of having enough RedBull..." -Rappstar

Mark,

Great data and information!

Two questions:

1. Did you use the large or small bento box?

2. Also, how much of the benefit of each component is additive? For instance, if you used the bento box AND profile aero drink, what would the aero savings be? You might not have done these specific tests, but I thought I would ask.

Interesting that Arundel Chrono is less aero, as I thought I had read that Landis did some wind tunnel testing and saw that it gave some improvement.

Keep up the good work!

Mark,

This is what I was hoping for when starting the thread. Thank you very much for the information. I am just in the process of getting an Aero Helmet and have settled on Louis Garneau Chrono which should be better than my Giro road helmet. I have aero wheels already so this should be the last piece of aerodynamics I will need other than continual work on my position.

-cghebert

I used the smaller Bento Box (branded "Bento Box") and not the AKona version or any of the variations. It was what I had available at the time but will test everything I can when I do follow up testing this spring.

In terms of the additive improvement, I unfortunately didn't have enough wind tunnel time to do all of the permutations of combining products. My theoretical assumption would be that using both together would give you some improvement, but probably less than the sum of the two. The products I'm designing will be made to work together aerodynamically -- so look for some things to follow the production of top tube aero bottle.

The Chrono was less aero than the bike and rider alone -- i.e. it did not improve the aerodynamics of the bike. However, if you compare it to a normal water bottle, it was significantly better. When Landis did testing, he focused on placing the bottles near the bottom bracket (this is an assumption based upon what he's using now -- if anyone knows about the specifics of his test, please correct me). His BMC has water bottle bosses very low on the DT to allow for the bottle to act as a fairing between the DT and ST. On my P3, there was a large gap between the bottle and the curved ST. Thus, I wouldn't expect any improvement. On Landis' bike though, this improvement makes sense.


I hope this makes sense and answers your question :) Keep 'em coming and I'll do my best to answer whatever curiosities you may have.

Happy training,

Mark
MIT Center for Sports Innovation
markcote@mit.edu

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Mark Cote
MITAerobike
Specialized Bicycle Components

-Bman

Good to hear :) Let me know if you have any other questions and I'll do my best to answer them more promptly.

Definitely consider the little things too (or often considered little things)....gloves, number placement on the bike, jerseys, tires (tire aerodynamics matters just as much as wheels), aero bottles (as discussed), etc, etc.

Good luck to you and kick some butt this season!

-Mark
MIT Center for Sports Innovation
markcote@mit.edu

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Mark Cote
MITAerobike
Specialized Bicycle Components

Hi Mark,

Interesting stuff, thanks for the post!

Two questions/comments: I wonder how things will look at different yaw angles? I'm suspecting that bottles such as the Arundel become more effective in a cross wind, which I'm suspecting may be one of the reasons it tested slower for you? Additionally, your bottle may even do better in a cross wind? I'm sure you know as well as any one, zero yaw is a pretty unrealistic condition--even on an indoor track.

Also, I'm guessing that the stem shape probably has a good bit to do with this as well, and I'm wondering if an integrated 'aero shaped' stem, i.e. the Vision integrated bar, could also significantly reduce the messy air behind the stem. Any thoughts?

Looks to me like two holes higher up on the Arundel cage would easily push it down to where it's connecting your down and seat tubes. Add a couple of small pieces of carbon cut to fill the gap between the bottom of the bottle and your BB (epoxied to the cage of course so they can easily be removed), and you've just created 7 or 8" of wind-invisible tube.

Chris

Mark,

Thanks for the picture of your baseline position; suddenly, these numbers begin to make more sense.

Your setup leaves quite a bit of real estate between your aerobars and frame, including a not unsubstantial amount of cylindrical steer tube. It doesn't seem to be a great leap in imagination to understand how a top tube fairing would help given this positional arrangement.

I would be quite curious to see how your numbers would look after testing an aerobar setup that was bottomed out on the headtube, and had no steer tube exposed....


.

---

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But do not buy the Chrono. Should I be thinking of the Rocket instead of the Chrono.

I do concider bottle placement as I only use an aero bottle on the aerobars and one on the seat tube. I do not use a behind the seat unit in races at all. Never wear gloves in a triathlon. Skin tight tops if possible and I am very careful of how I run my brake and shifter cables.

Can you go over the tire aerodynamics for us a bit when you have time.

Should I be running a 20mm up front and a 23mm on the back.

Thanks again for all the information.

A bottle on the seat tube is not a very good place for the bottle (aerodynamically) actually; you're better off putting it on the downtube. It's probably easier to reach too.

- Guo-Liang

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___________________________
Chewie
Slowtwitch Aeroweenie since '06

Do I have this right?
-Bento Box's improve dynamics behind the stem? I have an aero stem though so does that negate the advantage?
-The X-Lab, or any behind the seat system w/ 2 bottles is better than on the frame? I have a Hydrotail bit was thinking of ditching it come race day and just using the frame mounts.
-What if you have a bladed down tube but round seat tube, should you put a bottle on the seat tube to break up the rounded shape?

---

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MITaerobike;
Thanks for taking the time to make your informative post. This is the reason you can't beat this site. A bunch of guys talking about an aerodynamic waterbottle and then the MIT wind tunnel guy checks in.
I'm going to invest in Bento stocks because once the ST herd hears about the "aero-bento" advantage, they'll all be snapping them up and mounting them on their Cervelos.

Brad

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3SIXTY5cycling.com

First Q: My assumption (based upon lots of testing of other products in crosswinds) is that anything with a large amount of surface area on the side will only improve aerodynamics in crosswinds. I have only tested in headwind, but I designed the bottle to work in all wind situations (not just super narrow, but also tapered...pictures to come). Think aero helmet for a second -- plenty of data (and theory) about disc wheels helping in crosswinds, but aero helmets haven't been discussed. I conjecture that aero helmets help more and more in crosswinds (though they would also apply uncomfortable torque on the rider's neck) just as disc wheels do.

This is a post I would like to really get into, but can't right now (too might to write about!). I'll make sure to reply in the future though. For now just note that when testing prototypes, it's expensive to do more than one yaw angle and wind speed. I do plan on going through and doing yaw tests in the future. In general, if you understand how yawed aerodynamics work (how the vector components break down and how you actually get a component of thrust...a discussion to have later), then head on tests can tell you a lot. They are not the be-all, end-all but definitely help to make products more aero.

2nd Q: I always thought the Vision aerostem did nothing -- HOWEVER, tests over the last year have shown otherwise...that's why you see so many track bikes with aero stems behind the steerer. I conjecture that you need a bit more surface area (i.e. the fairing should be longer), but as this is coupled to the steering, 4-5cm seems safe. Like you said, 0 yaw is rare...usually more like +/- 5 degrees. Vision did their homework before and after the FSA buyout. The products were solid before and are still solid now.

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Mark Cote
MITAerobike
Specialized Bicycle Components

-fredly

There's exactly 2cm of spacers between the top of the HT and my stem. During the season, I drop the spacers and race right against the top of the HT. I'll just note that the bottle I've designed works with this variation in mind (i.e. it's not 15cm tall). Some riders will have no stack and others will have 4-5cm. Either way, the stem is still ~3cm tall and your arms are above that. The air going around the stem and bars is just as bad (if not worse) than just going around a cylinder. Also note that this is a 1" HT (not 1 1/8") and you'd expect a proportional change to the drag given a wider HT.

I do plan on testing with the stem/bars in varrying heights due to stack -- I'll let you know when it's done. Should be interesting to see the change, but I really don't expect much of one. Just the way the cable housing bends when you move stuff around changes the drag a ton. It's really incredible.

Thanks for the note -- I hope to give you more conclusive data in the future.

-Mark
markcote@mit.edu

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Mark Cote
MITAerobike
Specialized Bicycle Components

Bman

I haven't done comparative testing of the two helmets yet...that's coming up this Spring. You'll probably get 85% or more of the improvement off of the Chrono though and like has been mentioned before, your head/back shape really dictates what helmet you use and how you wear it. Don't stress it -- you have a faster helmet than you did before :)

The tires depend on what wheels you're running...I run a 404 up front a flat Zipp disc out back and run a 21mm front tire and a 19mm rear on the Zipp. The 404 rim was actually designed for a wider tire (21mm or 22mm -- Josh from Zipp could answer this for sure) but the disc can deal with a smaller tire for optimum. But honestly, the rear doesn't matter too too much as the air is already broken up back there.

Mark
markcote@mit.edu

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Mark Cote
MITAerobike
Specialized Bicycle Components

Mark,
Very, very interesting. I'm still digesting the data (particular the hydration results) but in the meantime could you tell us what the basic accuracy of the wind-tunnel balance is and what is it's repeatability? In one passage you mention repeating the test three times - how many runs were done for the others? If multiple runs can you share the range, Cv or other metric to give us an idea of the data spread. As an enginerer, I'm always a tad suspicious of single numbers (in general).

Again very interesting and thanks for sharing your data.

I do not have braze ons on the down tube so the seat tube is all I have. From my understanding it is better than the down tube and a lot better than behind the seat.

"There's exactly 2cm of spacers between the top of the HT and my stem."

Which to my mind is a fair bit...



"During the season, I drop the spacers and race right against the top of the HT. I'll just note that the bottle I've designed works with this variation in mind (i.e. it's not 15cm tall). "

OK.

"Some riders will have no stack and others will have 4-5cm. Either way, the stem is still ~3cm tall and your arms are above that. "

Not necessarily.

"The air going around the stem and bars is just as bad (if not worse) than just going around a cylinder. "

Not sure how this is relevent, and your position (minus the fairing) seems to include both...


"Also note that this is a 1" HT (not 1 1/8") and you'd expect a proportional change to the drag given a wider HT. "

Sure. Again, relevence?

"I do plan on testing with the stem/bars in varrying heights due to stack -- I'll let you know when it's done. Should be interesting to see the change, but I really don't expect much of one."

OK - care to expand on this? What do you think is causing the reduction in drag you cite, and how would this be independent of positional changes that have a direct effect on airflow in the area of the bike you are manipulating with your fairing application?

Aren't you, in effect, replicating the design of, eg, a Look style front end, by fairing the stem area of the bike into the top tube?

"Just the way the cable housing bends when you move stuff around changes the drag a ton. It's really incredible. "

Yup.

"Thanks for the note -- I hope to give you more conclusive data in the future. "

You're welcome, and thank you.I look forward to the data.


.

---

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-rmur

I hear you entirely -- Too much information often confuses more than it helps, but here you go: Our repeatability in the wind tunnel is very good. The wind tunnel test setup is fairly dialed and the balance gives us results with standard deviations around 1/100 of a lb (.01 lbs). This is after the wind speed is corrected to standard atmospheric conditions. Of course, once you pull a product out, get a rider back on the bike, etc, etc. you have introduced several variables. I got data within .03 lbs between different tests of the bottle (not back to back)...back to back tests were within .01 of a lb. These variations are usually more due to the rider slightly shifting in the wind tunnel. However, testing without an athlete would be completely useless.

I just want to reiterate to everyone reading this post though that wind tunnel time is super expensive and only so much time could be devoted to prototype testing. Once a production model comes out, I'll share more data with you all. That is my focus going forward and I really want to help explain more and more. At this point though, I'm not claiming I can save everyone in the world 2 minutes over 40km....I'm just saying that my prototype does that on my bike :) The final time savings may be more or less, but at least I'm trying to share what I do know. Only a few other people have done this testing on water bottles and it generally agrees with my findings.

One more quick thing too -- this is the only data I can show now, but let me reiterate that I've been testing products and athletes for around 4 years now. Though yaw data explains more about a product, understanding what you'll probably see in that yaw data is just as useful. If I spend 365 days a year testing and post all of that data, it doesn't make better products. I will focus on pulling together data and then using it in the most useful way: sharing it and then developing products that utilize the research time. It'll be a split going forward for sure.

Thanks everyone for reading and asking questions. It's good to see how many people really care about aero these days :)

Mark
markcote@mit.edu

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Mark Cote
MITAerobike
Specialized Bicycle Components

This has been a great thread! Thanks Mark and all those involved for the thoughtful questions and incredible information. Amazing stuff here.

That's all, I'm not going to pretend I have anything to add...

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Jim Manton / ERO Sports

okay taking 0.03 as the 'accuracy baseline' most of the differences noted were well above that 'noise' level. Speaking loosely here of course :)

thanks for the info ...

BTW, I figure your baseline position Cda is down around 0.225 ... purty slick.

Mark-
Thanks for sharing some good data. I (and many others) enjoy triathlon as a training / tinkering hobby. I like to workout, and I like to tinker. aerodynamic concepts always seem like part voodoo and part science. I like hearing experience from someone spending time in the tunnel. Good luck with graduation and marketing your ideas.

Cool data. It would be interesting to see what happens if you get that Arundel closer to the seat tube. I have heard of people drilling out the carbon cage to get it closer so that its more of a fairing.

Your information has made me into a total aero weenie (ie the homemade front skewer that barely exists) Probably doesnt save me more than a 1/2 second but I like it. See below:




Plus it only weighs 16 grams :)


Dura Ace Baseline:

Jeremy

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Want: 58cm Cervelo Soloist. PM me if you have one to sell

Vintage Cervelo: A Resource

Jeremy,

What was the starting point of the skewers. I would like to see what they looked like before and after.

Thanks.

Mark,

Is there a reason you guys don't wear the "Bionic Wings" with your aero helmets?

Just wondering if you have tested to see if they actually make a difference.

Thanks!

Hahahaha

Two reason:
1. When we got the helmets, we got some of the early ones before the "wings" were available.
2. For team time trial, communication is key and when we've tried ear covers in the past, we can hear each other yelling "On", "Gap", etc.

Aerodynamically, it would make sense that they would help, but I haven't tested them so idk for now.

Mark
markcote@mit.edu

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Mark Cote
MITAerobike
Specialized Bicycle Components

I have a question for you about water bottles on a round seat tube. It has been written that you said it was faster to use a water bottle as to not. My question is, would I be better/faster to use a normal water bottle or an Arundel Crono water bottle?

Thanks for sharing your data with us.

I would like to see if someone could do a test to see how much a skewer actually affect the wind. Especially the front one.

...so we've got 4 pages of posting and STILL no pic of this magical freakin' water carrier. Is this a matter of national security of something? It never happened unless there are pictures, right??

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________________________________________________________________________
"that which does not destroy me will only make me stronger" Frederick Nietzsche
andrew peabody
http://BREAKAWAYMULTISPORT.COM

You have to read the MIT post within the thread and you will get your answer.

why would he post a pic of something hes still developing until hes got it right and patented. :)

I HAVE read the entire thread, including all of the amazing claims, various descriptions, etc. With the just the info that's been passed around the internet forums, any enterprising person out there with visualizing skills and manufacturing capabilities could easily bring something to market in a minute if they wanted to. I would think that a patent would have been applied for well before building a prototype , or at least before publicizing it so much, and if patent is pending, a photo from the tunnel and some data to back up the claims is not an outrageous request. If I were developing something that could be so revolutionary, I wouldn't be talking so freely if I hadn't taken steps to protect myself.

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________________________________________________________________________
"that which does not destroy me will only make me stronger" Frederick Nietzsche
andrew peabody
http://BREAKAWAYMULTISPORT.COM

There is a Patent Pending and I do have legal protection. If anyone would like to discuss this in a more direct manner, please contact me personally.

Mark Cote
markcote@mit.edu

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Mark Cote
MITAerobike
Specialized Bicycle Components

[reply]
There is a Patent Pending and I do have legal protection. If anyone would like to discuss this in a more direct manner, please contact me personally.

Mark Cote
markcote@mit.edu[/reply]
Is this something that is even patentable? Is it novel? Not sure. This place - http://www.twofish.biz/bike.html - sells a bottle holder that can be mounted anywhere, including the top tube. The claim that the bottle improves aerodynamics can be universal. Too much upstream can affect overall rider+bike aerodynamics. While it worked for you, it is conceivable it may be of no aero benefit (or even an aero detriment) for another rider+bike due to completely different configuration changes. Just like some riders are more aero with elbows closer together than other riders, some helmets work better than others, etc.

The location isn't novel. Check the 2006 Marin Mount Vision - http://www.marinbikes.com/bicycles_2006/html/bikes/bike_specs/specs_mt_vision.html. While it's a mountain bike and not a time trial bike, I'd have to wonder if the precedence of that location will affect things.

Good luck with it, but it seems like it could be a difficult sell.


By the way, seems almost obvious which bottle this is (and you have to love the language) -

A sports bottle includes a generally cylindrical hollow vessel having a liquid chamber formed therein and a closed end bottom. The generally cylindrical vessel further defines a reduced diameter neck portion and an upper chamber terminating in an upwardly facing mouth. The upper chamber supports a porous antisplash element preferably formed of a coarse porous foam material plastic or the like. An elongated tubular straw extends from the bottom surface within the vessel upwardly through the neck portion and through the antisplash element and beyond the mouth to form an upwardly extending end which receives a flexible mouth tube which is preferably curved toward the user when the sports bottle is secured to a conventional bicycle. In alternate embodiments, the antisplash element within the upper chamber of the vessel is formed of a plurality of tubular members defining passages therethrough and grouped together to form a generally cylindrical multipassage combination. In still further alternate embodiments, a flexible planar member having a plurality of flexible generally triangular segments is secured to the mouth portion of the vessel to provide an antisplash element. In a still further alternate embodiment, a generally planar valve member is pivotally supported within the mouth portion of the vessel and is pivoted to an open position as liquid is poured into the vessel mouth.

Tigermilk, were there not three spoke plastic/composite bmx wheels before Dupont created the trispoke? Your being so picky for no goddamn good reason.

Your little soap box paragraph will unliely sway the U.S. patent office.

Way to go Mark.

Hell, if anything I gave some clues of things that could be similar so that he can build arguments as to why they are unique. As to why DuPont got a patent? Beats the heck out of me unless no similar patent existed or perhaps the novel concept was the process (the patent for the wheel does call out a fairly specific process).

Have any test been done on the NeverReach system? if so are the results significant in terms of time savings?

Mark,
Thanks again for joining the thread. With regards to the wheel data. I read this originally in Bicycling magazine and was just amazed that wheels weren't more important. The "aero helmet more important than wheels" stuff just seemed crazy, but heck, I've got an open mind and this is fascinating stuff.
I do see from your data (in this thread anyway) that you compared Zipp 999's to Krysriums, not a traditional 32 hole wheel. Nevertheless, that little of a difference in drag will have us rethinking expensive wheel purchases.

A few important questions though:

1) Did you normalize for wattage output to spin the wheels? This has often been overlooked in testing(at least in the early days). Sure wheels have X lbs of drag compared to a static helmet, but how much faster do you go because of the watts available that you don't have to use to spin the wheel? John Cobb has talked about this and it's significant. It takes very little watts to spin a disk, and quite a few to spin a traditional wheel at 30 MPH through air. When it comes to wheels, we can't just talk lbs of drag and extrapolate to time saved. It's all about the watts. Frontal area at zero yaw and drag on the sensor is just one component.

2) Did you account for different yaw angles? Both drag and wattage to turn a wheel very sharply at yaw angles and this is where surface area wheels excel.


I applaud the research you guys are doing, but I think wheels are much more significant.

Quake

This is true. A bottle on the downtube or no bottle at all hardly makes a difference. It's one of those wonderfully inexplicable aero results, but it happens all the time. We did it once again with Frank Schleck in the tunnel, riding with a bottle on the downtube, then tossing it to the side and the drag hardly changes. It does however seem to be important that the bottle is not too close to the rider's feet.

But put one on the seattube and all hell breaks loose. Not a problem in training of course, but in racing keep it on the downtube only, or use a different hydration system altogether (ADS, behind the seat, Camelbak, etc).

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Gerard Vroomen
3T.bike
OPEN cycle

I've always found this John Cobb test informative:
http://www.profile-design.com/...s/water_bottles.html

The findings agree with your point in that down tube bottles are good, even better than no bottle. But seat tube bottles are also an improvement over no bottle, though not as good as a down tube one. However, he finds both bottles at the same time are worse than no bottles. An aero bar bottle works best, though. So, ideally one downtube bottle ane one aero bar bottle.

He tests the bottles on a QR Tiphoon, but I wonder if things wouldn't change a bit with a round seat tube as I have on my QR PicanTi. In this case, I'm guessing a seat tube bottle would probably trump a down tube bottle, since a vertical, round tube is such a drag.

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Outside of my bike, my running shoes are my favorite things. Inside my bike, it's too cramped to run.

Our findings aren't quite like that, but it is dependent on the frame (and to some degree the rider).

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Gerard Vroomen
3T.bike
OPEN cycle

   
Yup. I've observed this with the P3 and the Felt DA. In the wind tunnel, a Campy biodinamica was slightly slower on the P3. In field tests, it was either very slightly slower or very slightly faster. I believe Scot had the same results in the wind tunnel.

By contrast, an Arundel bottle on the seat tube of the DA is not looking so good. I haven't done the all-out formal test yet, but it's looking measurably slower.


-- jens

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My latest book: "Out of the Melting Pot, Into the Fire" is on sale on Amazon and at other online and local booksellers

So Gerard, what is the fastest option for a P2SL rider? (other than to sell it and buy a P3C??) Assuming the rider uses a variety of wheelsets (Zipp 303, Specialized 3-spoke, and maybe a disc).

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Swimming Workout of the Day:

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2020 National Masters Champion - M50-54 - 50m Butterfly

Put a bottle on the seattube for training, not racing. ADS, behind the seat, all viable options (of course the seattube is also a viable option, just not as good, though better than downtube AND seattube).

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Gerard Vroomen
3T.bike
OPEN cycle

Gerard,
any experience with the Arundel (on Bontrager) aero bottle and the P3/P3C frame? if not, what would your opinion be for such a bottle on the downtube vs. a std. bottle?

Gerard,
Why are the only bosses on a P2SL and Dual on the seat tube if you've found that the downtube is a better spot? I'm confused.

Quake

Gerard --
If this is the case, why can you only put a bottle on the seattube and not the downtube on a Dual (and also the P2SL, I believe)? The soloist has spots for bottles on both seattube & downtube so it seems possible, no?
thanks,
tom

what is a ADS?

aero drink system.... profile, jetstream...

Here's a photo of that prototype bottle that was discussed a few months ago...

Yeah baby! Turn your multi-thousand dollar TT/Tri bike into a 1940s cruiser bike with the fake "gas tank"...yeeha!

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http://bikeblather.blogspot.com/

So what do you think....fairing? Waterbottle? What would the UCI think?

How is that any different than an Arundel or a Bontrager Speed bottle? It just happens to not attach in the same place.

What would the UCI think? Who knows? Would Obree use it? If so, then it won't be allowed ;-)

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http://bikeblather.blogspot.com/

Ever since the talk about this bottle started, I have been trying to figure out how to make my own. I'm almost to the point that I want to boil a gatorade bottle and crush it in a vice. Any ideas?

No bottle ideas...but if you want to get most of the "savings", just go get a "bento box" :-)

It would probably be a good idea IMHO to "field test" it before using it in competition though, since like most things aero, I'm sure that the "savings" may be user specific.

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http://bikeblather.blogspot.com/

well simple
make a model of plaster wipe a cheap carbon on it backed ,wipe out the plaster with water
ready the macig bottle

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http://www.ada.prorider.org
skype ceesbeers191053