Not to rehash old news, but is there a clear position on where the best water bottle placement is in terms of aerodynamics? I am seeing a lot of behind saddle systems and have a profile aerobottle, but I am trying to figure out the “most aero” way to keep one bottle’s worth of water for shorter races. Thanks…and flame on if necessary…
PS: I hate the bento box theory, and I think the profile system is messy and busy, but effective.
There are two places that will actually give you an aero advantage, the downtube and between the aerobars. Everywhere else will hurt you including those no-hands reservoirs that go behind the seat. For 30k or less I go with one 24 ounce bottle on the downtube. More than that and I add the profile between the bars.
If you only want to keep one bottle of water on the bike for a short race, I would use a profile aerobottle or Jetsteam as it is the easiest and most effective way to get water in your mouth without having to move very much. Maybe a neverreach but I honestly do not think it is more aero than a bottle between the aerobars.
Training rides are a perfect time to use behind the seat holders but for racing I would not go with them. In racing no matter what the distance is, I only use a bottle on the downtube and an aerobottle between the aerobars.
Just keep it as simple as possible.
There are two places that will actually give you an aero advantage, the downtube and between the aerobars. Everywhere else will hurt you including those no-hands reservoirs that go behind the seat.
Can you please cite your sources?
One place was right here on Slowtwitch:
http://www.slowtwitch.com/mainheadings/techctr/waterbottles.html
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i’d certainly like to see some more recent data because with all the prevalent tunnel testing available to pros today there are still a significant number using bottles behind the saddle…
Contrary to some of the posts on this thread, we’ve found that the frame-mounted wb’s can cause more drag than either bar-mounted or behind-the-seat systems. Here’s a previous post I made on this subject, based on our wind tunnel testing last year:
"We tested a few bottle/hydration options on the Airfoil Pro bike. I’d have to go dig up the drag numbers, but the bottom line was:
On race day, I would go for the behind-the-seat or in-the-aero-bar option, or both, before the downtube w.b. And again, this was on a no-seattube Airfoil Pro, so might be different for other frames."
I believe the more aero your basic frame design is, the more the above will apply.
-Preston
I use either a… single bottle mounted with an older model Zipp carbon bottle cage between the aerobars (ala Vison Tech) OR a single bottle mount drilled directly into the rear plastic piece on the seat. This last option has the bottle mounted snug up into the rear of the seat at a 45 degree angle. I don’t use any of the behind the seat “systems”. Most of them sit way too far behind the seat for me…and I have very long arms.
Many years ago I tried the Jetstream style in between the aerobars but it was way too heavy for me and I never needed that much fluid, even in a IM.
Not enough flames in this thread 
(Really, just kidding, but …)
What about a CamelBak or equivalent?
Cheers, Richard Nelson
who doesn’t use a CamelBak but has a fast friend that does
in Toronto, Ontario, Canada
i saw the study that gave the tri bar bottle the best result and behind the seat the worst - but personally i just go with what i prefer and i like normal bottles best
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so are the manufacturers clueless or are they helping us out?
I agree plus I dont like the weight of two full bottles up high. I like the weight lower, bike handles better for down hill corners and climbing.
I have not posted anything on this forum for a long time but today I am on the roll 
To answer your question the ideal place for the drink would be inside the frame of the bike. And the drinking tube would come out from the frame for you to drink. If you are obsessed about dynamics this would be very aero and super cool not terribly practical but for a 40Km fantastic performance. Now we do not design bikes at this time but I think for any company that makes them that would be the most logical step in frame development. Honestly the amount of $ that is put to do CFD analysis on frames and then the end user puts a regular bottle cage with regular bottle on it and ruins all of that including some of the benefit of having a $5000 aero frame… is painful to see.
The number one cause of drag is the part with the biggest cross section that the is seen by the airflow and that would be you the rider, everything ales is secondary. So I would focus on your position and then worry about all the other details.
This would help you make the right decision.
Now to answer your question the most efficient position of the bottle from 5deg up 20deg angle of attack is on the seat tube.
We will have more data this spring when we are working on the AEG Toshiba Pro Cycling Team TT skin suits. I will post more data once we complete these tests in February/March, including the in-frame hydration system.
Cheers
How about just putting a standard 24 ounce bottle in the back pocket of a tight fitting cycling jersey?
Wouldn’t this position “hide” the bottle in the wind shadow of your helmet/upper back?
I’ve always raced multisport in a standard cycling jersey with three big pockets in back. Lots of space for nutrition, a water bottle, works fine to run in (without a nutrition belt), and has that nifty zipper front.
Is this an aerodynamic faux pas?
Wow…
No mention of the MIT water bottle that sits on the top tube hiding behind the stem. That has been shown to improve aerodynamics.
No mention of how these numbers are like with and without a rider on. Sure, a behind the seat hydration system tests horribly when the bike is without a rider, but with a rider, that effect is almost completely negated.
No mention that whether the Profile aerodrink (and other aerobar mounted bottles) helps aerodynamically is really dependent on where on the aerobar it is situated, and how close the aerobottle is to the headtube (or how long your stem is).
Paulo isn’t here; I guess it’s safe for me to post… (=
No mention of the MIT water bottle that sits on the top tube hiding behind the stem. That has been shown to improve aerodynamics.
**
And also no mention of the bottle that Santa uses on his sled, either. I heard it has also been shown to improve aerodynamics.
Did you test a traditional bottle/cage inside the frame or an aero bottle?
Good question. Those tests were with traditional (round) wb and cage. Large size bottles.
And as chewgl points out, it matters if the rider is in place. These tests were with rider (Macca) on the bike.
-Preston
Another question I always wonder about is: How often is the rider actually drinking? Is that position shift (if any) taken into consideration when testing?
With behind the seat bottles, some riders have to sit up and turn halfway around to access them, drink, and put the bottle back. Obviously, some riders with some systems are alot more streamlined about this whole procedure. With the bottle in the aerobars, your position is not broken the entire time.
I have a question on this.
So we decide that bottle A located at point Z is better than bottle A located at point X. What kind of difference are we talking? 5 seconds in a windtunnel? , 5 seconds with a static bike with a simulated 25mph tunnel and no rider? … all this debate is great, but the difference this water bottle really makes surely is the same as not drinking at all and never leaving the tuck position? don’t drink …lol,but what if we took 2 more gulps eveyrtime we drank,thus the average for each event would be 10 drinks less and 10 less disruptions to the aero tuck ??? But just how much time is saved? and would an extra 10 yards every time you swam, and 100 yards everytime you ran over all the years training make the same difference? I wonder where Graeme Obree would put his Whiskey Flask to save time?
Cheers
Deano