# water bottle placement?



## T K (Feb 11, 2009)

So I have spent (wasted) the day searching this to come up with no clear answer.
I have a road bike (caad 5) which I have turned into my TT bike. I bought an Arundel Chrono water bottle and cage and am trying to figure out if it would be more aero on the down or seat tube. From what I have read this can make more difference than some may think. Many studies and opinions out there just no clear cut info. I won't go in total depth of what I have found, but it has been all over the map. It seems to depend if you have an aero frame and non aero bottle. Or, non aero frame and bottle or aero frame and aero bottle. Just can't find non aero frame (round tube) and aero bottle. 
Please lets not make the tired arguments about train harder, its the engine, you'll save more watts with ceramic bearings bla bla. Let's assume I've done that. Just looking for some data.
Thanks


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## cxwrench (Nov 9, 2004)

i'd think the best position would be the one that fills in the space at the downtube/seattube junction. that might be w/ the cage on the seat tube...
take photos of both and post them...let's see what both spots look like w/ the bottle in the cage


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## redondoaveb (Jan 16, 2011)

According to Bicycling.com, seat tube is the most aero spot.


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## jcgill (Jul 20, 2010)

Just by imagining in my head, i would think that the seat tube is a little more aero, as the down tube is blocking the seat tube already, so the bottle is sheltered from the wind.


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## qatarbhoy (Aug 17, 2009)

If it's that important to you, behind the saddle is more aero. Get one of those rocket-launcher-type bottle holders instead.










Or do this:


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## T K (Feb 11, 2009)

cxwrench said:


> i'd think the best position would be the one that fills in the space at the downtube/seattube junction. that might be w/ the cage on the seat tube...
> take photos of both and post them...let's see what both spots look like w/ the bottle in the cage


Yes, this was one school of thought I have encountered. And it is most definately closer to the BB and filling the void attached to the seat tube. I could even redrill the cage with lower holes to get it within an inch. But here is where what I have read is getting me. Studies have shown that a round tubed bike, especialy one with large tubes, like mine, benefits from an aero bottle on the down tube. Gives the round tube an airfoil shape. But I have also read studies saying a bottle on the seat tube was definately better. Acted as a cowling to the rear end so to speak I guess. But was that with a round (traditional) bottle or aero? I could see the aero bottle on the seat tube creating a wedge, wich might help especialy with a disc. But I can see the down tube (airfoil) being just as important. Like I said, I would love to see some data. Non aero bike, aero bottle.


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## T K (Feb 11, 2009)

qatarbhoy said:


> If it's that important to you, behind the saddle is more aero. Get one of those rocket-launcher-type bottle holders instead.
> 
> 
> 
> ...


If I had to look like that to win anything I'd rather stay home and drink beer.


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## qatarbhoy (Aug 17, 2009)

> _If I had to look like that to win anything I'd rather stay home and drink beer. _


I agree, some things are a step too far. I'm just warning you, this is where worrying too much about aerodynamics leads.


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## ericm979 (Jun 26, 2005)

Behind the seat bottles are actually less aero.

But the aero difference with water bottle placement is small. Your position on the bike is much more important.


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## AndrwSwitch (May 28, 2009)

T K said:


> If I had to look like that to win anything I'd rather stay home and drink beer.


Was thinking something along those lines myself.

Honestly, I think it would be less bad if he skipped the goofy tri top.

From the pic, it looks like the shape is tapered? I'd think that would work a little bit better on the down tube - to rejoin the air, like the tapered end of a rain drop. Of course, with your seat tube and rear wheel right behind it, that might not be that useful. But at least it would calm down some of the turbulence behind the down tube. Making the open space smaller, regardless of placement, should help too.


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## Fredrico (Jun 15, 2002)

*John Cobb would agree.*



ericm979 said:


> Behind the seat bottles are actually less aero.
> 
> But the aero difference with water bottle placement is small. Your position on the bike is much more important.


Don't have a link, but read a few years ago some data gathered by John Cobb, the guy who originally did testing with Lance Armstrong in the wind tunnel at A & M University. He found no appreciable advantage to water bottles behind the saddle. Seems like the front wheel breaks the wind around the down tube. He concluded mounting on the down tube and seat tube had slightly less wind resistance than up higher. And of course, the differences are greatly overshadowed by rider positioning.

Putting the considerable weight of two water bottles low on the frame also lowers the center of gravity and improves bike handling, like sprinting and slaloming around switchbacks. This would be preferred for normal road riding, not necessarily straight line time trialing. :biggrin5:


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## qatarbhoy (Aug 17, 2009)

Thanks eric and Fredrico for clarifying! I knew my tri-geek buddies were wrong all along, should trust my instincts next time.


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## notclinteastwood (Aug 1, 2013)

I know this is an old thread but I am posting this for the benefit of anyone that may view this thread in the search for an answer to the most aero bottle position. Like I have been doing. And after research and trial and error I have the results of my research and testing. 

Im not sure about seat tube vs down tube but whatever you do, if you only require one bottle, use one cage. The empty cage has the same drag effect if it contains a bottle. 

If you are using aerobars, the best thing to do is zip tie a bottle cage horizontally between the bars. This is the most effective position aerodynamically and has basically 0g of drag. The bottle is also then at your fingertips to drink from without having to come out of your aero position. 

Cages behind the saddle look crap, and they are not easily accessible. There are camelbak style options that have a straw and attach to your bars/top tube, all you have to do is bend your head down and take a sip (look ma, no hands!). These do have aero disadvantages but are practical.

If you use aero bars I would 100% reccomend strapping a cage to them horizontally. It's cheap- you don't need no arundel aero bottle that costs a load- it's also practical, and it has- as I've mentioned- virtually no drag.


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## bwbishop (Sep 17, 2011)

Just send them here. 

http://www.cervelo.com/en/engineering/ask-the-engineers/hydration-and-aerodynamics.html


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## notclinteastwood (Aug 1, 2013)

bwbishop said:


> Just send them here.
> 
> Hydration and Aerodynamics - Cervélo


I knew Cervelo did a test but couldn't find the link!

So just to back up what I said earlier (to anyone scouring this thread), please see the Cervelo link!


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## mikeyc38 (Sep 8, 2011)

T K said:


> If I had to look like that to win anything I'd rather stay home and drink beer.


What's that behind his seat, a spoiler?


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## froze (Sep 15, 2002)

T K said:


> Yes, this was one school of thought I have encountered. And it is most definately closer to the BB and filling the void attached to the seat tube. I could even redrill the cage with lower holes to get it within an inch. But here is where what I have read is getting me. Studies have shown that a round tubed bike, especialy one with large tubes, like mine, benefits from an aero bottle on the down tube. Gives the round tube an airfoil shape. But I have also read studies saying a bottle on the seat tube was definately better. Acted as a cowling to the rear end so to speak I guess. But was that with a round (traditional) bottle or aero? I could see the aero bottle on the seat tube creating a wedge, wich might help especialy with a disc. But I can see the down tube (airfoil) being just as important. Like I said, I would love to see some data. Non aero bike, aero bottle.


That study is correct for round tubes. Round bottles could actually be a bit wider than the frame tube thus it would be better to use aero bottle.

Here are some tests about this sort of thing though not inclusive; see: Bicycles and Aerodynamics


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## T K (Feb 11, 2009)

Wow! So I have not been on here or my bike for that matter, in months. Thinking about getting my fat a$$ back on the saddle and doing some training for next year. The last two years have been about family, home and business. 
Thanks for dredging up an old thread for me. Kind of gets me motivated.
Oh, and I finally got a proper TT bike and put an aero bottle on down low.


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## mpre53 (Oct 25, 2011)

qatarbhoy said:


> Or do this:


That gut doesn't look very aero.


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## JGSnCA (Sep 2, 2013)

T K said:


> If I had to look like that to win anything I'd rather stay home and drink beer.


This pic has really made me nauseous. Honestly, this is disturbing. I think I'm going to give up cycling and take up RC airplanes.


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## T K (Feb 11, 2009)

JGSnCA said:


> I think I'm going to give up cycling and take up RC airplanes.


I know a guy who has done just that. Too bad, he was a beast on a bike.


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## T K (Feb 11, 2009)

mpre53 said:


> That gut doesn't look very aero.


What he lacks in aero, he makes up for in sexy!


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## froze (Sep 15, 2002)

T K said:


> I know a guy who has done just that. Too bad, he was a beast on a bike.


People are strange, I knew a guy that would pick up a hobby and master it in one to two years then get bored and find another; mostly artistic hobby's he excelled at. Picked up the guitar and in one year could make a acoustical guitar sound like 2 people were playing two guitars and won some sort of contest for doing so. Then it did the same thing with photography, one year of getting into photography he had a calendar issued featuring his pictures and won a expensive camera outfit for doing so.

But for me, I'm sort of a simple guy, I like to ride and I do it for my health, and as fun as RC flying might be it would do nothing for my health. I use to fly my own ultralights but I also rode a bike too, so at one time I had two hobbies...well maybe 3 if count the cars, but the cars don't take up a lot of time unless something breaks.


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## jkuo (Mar 30, 2008)

Only downside to putting the bottle between the aerobars is that they launch much easier. Right now my TT/tri bike is my only road bike and the only bottle I have on there is between the bars. It's great when I'm actually riding aero since my arms keep it in place. But if I'm riding on the base bars, the bottle launches a lot. I'm guessing it's because the bars see more movement than the frame. I've just been too lazy to swap the cage.

And one minor downside is that when the bottle is full, you can notice the weight while turning or sprinting. Not that much of either is done on a tri bike.




notclinteastwood said:


> If you are using aerobars, the best thing to do is zip tie a bottle cage horizontally between the bars. This is the most effective position aerodynamically and has basically 0g of drag. The bottle is also then at your fingertips to drink from without having to come out of your aero position.
> 
> Cages behind the saddle look crap, and they are not easily accessible. There are camelbak style options that have a straw and attach to your bars/top tube, all you have to do is bend your head down and take a sip (look ma, no hands!). These do have aero disadvantages but are practical.
> 
> If you use aero bars I would 100% reccomend strapping a cage to them horizontally. It's cheap- you don't need no arundel aero bottle that costs a load- it's also practical, and it has- as I've mentioned- virtually no drag.


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## azurenak (Aug 25, 2013)

i've heard that the bottle on the seat tube is more aero than on the down tube


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