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Re: Official MIT information thread. HOPEFULLY [Bman] [ In reply to ]
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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
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Re: Official MIT information thread. HOPEFULLY [TriTalk] [ In reply to ]
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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.
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Re: Official MIT information thread. HOPEFULLY [TriTalk] [ In reply to ]
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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
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Re: Official MIT information thread. HOPEFULLY [chicanery] [ In reply to ]
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If you guys would like, I can Email MIT Cycling and ask them to post up.... let me know.

"Pace is just a matter of having enough RedBull..." -Rappstar
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Re: Official MIT information thread. HOPEFULLY [BlakeSKI] [ In reply to ]
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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.
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Re: Official MIT information thread. HOPEFULLY [chewgl] [ In reply to ]
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im going to try and make my own, by making a carbon fairing and putting a small water bottle inside of it.

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

Vintage Cervelo: A Resource
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Re: Official MIT information thread. HOPEFULLY [Bman] [ In reply to ]
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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.

"Pace is just a matter of having enough RedBull..." -Rappstar
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Last edited by: MITaerobike: Jan 30, 07 8:00
Re: Official MIT information thread. HOPEFULLY [MITaerobike] [ In reply to ]
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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!
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Re: Official MIT information thread. HOPEFULLY [MITaerobike] [ In reply to ]
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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.
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Re: Official MIT information thread. HOPEFULLY [cghebert] [ In reply to ]
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-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

--
Mark Cote
MITAerobike
Specialized Bicycle Components
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Re: Official MIT information thread. HOPEFULLY [Bman] [ In reply to ]
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-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

--
Mark Cote
MITAerobike
Specialized Bicycle Components
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Re: Official MIT information thread. HOPEFULLY [MITaerobike] [ In reply to ]
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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?
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Re: Official MIT information thread. HOPEFULLY [MITaerobike] [ In reply to ]
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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
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Re: Official MIT information thread. HOPEFULLY [MITaerobike] [ In reply to ]
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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....


.

Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/
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Re: Official MIT information thread. HOPEFULLY [MITaerobike] [ In reply to ]
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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.
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Re: Official MIT information thread. HOPEFULLY [Bman] [ In reply to ]
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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

___________________________
Chewie
Slowtwitch Aeroweenie since '06
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Re: Official MIT information thread. HOPEFULLY [chewgl] [ In reply to ]
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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?

-Of course it's 'effing hard, it's IRONMAN!
Team ZOOT
ZOOT, QR, Garmin, HED Wheels, Zealios, FormSwim, Precision Hydration, Rudy Project
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Re: Official MIT information thread. HOPEFULLY [MITaerobike] [ In reply to ]
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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

3SIXTY5cycling.com
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Re: Official MIT information thread. HOPEFULLY [roady] [ In reply to ]
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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.

--
Mark Cote
MITAerobike
Specialized Bicycle Components
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Re: Official MIT information thread. HOPEFULLY [fredly] [ In reply to ]
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-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

--
Mark Cote
MITAerobike
Specialized Bicycle Components
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Re: Official MIT information thread. HOPEFULLY [Bman] [ In reply to ]
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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

--
Mark Cote
MITAerobike
Specialized Bicycle Components
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Re: Official MIT information thread. HOPEFULLY [MITaerobike] [ In reply to ]
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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.
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Re: Official MIT information thread. HOPEFULLY [chewgl] [ In reply to ]
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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.
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Re: Official MIT information thread. HOPEFULLY [MITaerobike] [ In reply to ]
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In Reply To:

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.




This got lost in a thread titles 'Cosmics', but there's some tire width data in here that may be of interest: http://forum.slowtwitch.com/gforum.cgi?post=1174850;search_string=cosmic;#1174850
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