# Effect of Water Bottles on Aero Frames



## bernithebiker (Sep 26, 2011)

OK, so you've just bought your dream aero road bike. 

Hours of wind tunnel testing, graphs that show it to be better than any other aero frame out there, a sexy video with soft lighting and pumping music. Free speed. Fantastic.

Then you bolt on your two water bottle cages and bottles. 

That beautiful tear drop / kamm tail down tube, just became a figure of eight.

Is this a problem or not?


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## Blue CheeseHead (Jul 14, 2008)

If one is that hung up on aero it is. One could reduce the impact by using the bottle cages that bolt to the back of the seat, just run one bottle on the seat tube or hire a domestique to follow you and hand you bottles at your whim.


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## wim (Feb 28, 2005)

Blue CheeseHead said:


> One could reduce the impact by using the bottle cages that bolt to the back of the seat,


Last time I looked, the bottle at the back of the saddle was said to be one of the worst places you could put it as far as aerodynamics are concerned. But for every cycling-related study that claims something, there seems to be another that says "not so," so take this with a grain of salt. And to keep this in perspective: in one study (John Cobb), bottles behind the saddle added 19 seconds to a 25-mile ride compared to no bottle at all. (Added 9 seconds compared to bottles on seat- and downtube.)


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## tihsepa (Nov 27, 2008)

Really?


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## cda 455 (Aug 9, 2010)

bernithebiker said:


> OK, so you've just bought your dream aero road bike.
> 
> Hours of wind tunnel testing, graphs that show it to be better than any other aero frame out there, a sexy video with soft lighting and pumping music. Free speed. Fantastic.
> 
> ...



Maybe this thread will answer your question:

http://forums.roadbikereview.com/pro-cycling-race-discussion/illegal-water-bottles-269093.html


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## Wadl (Oct 8, 2011)

just wear a camelback UNDER your shirt !!! LOL


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## Kontact (Apr 1, 2011)

This is the reason the Cervelo S5 looks the way it does.


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## bernithebiker (Sep 26, 2011)

cda 455 said:


> Maybe this thread will answer your question:
> 
> http://forums.roadbikereview.com/pro-cycling-race-discussion/illegal-water-bottles-269093.html


Interesting, so aero bottles are to be banned.

So presumably it is now impossible to stop your big round water bottles totally messing up your aero frame's aerodynamics....?


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## bernithebiker (Sep 26, 2011)

Kontact said:


> This is the reason the Cervelo S5 looks the way it does.


Well, at least they seem to have thought about it, but even so, the bottle is alot wider than the down tube, and who knows what size/type of bottle the rider is going to use?

It just surprises me that there isn't an aero road frame out there (not TT) that sells you a special bottle WITH the frame that mimics the shape of the downtube so smoothing air flow.


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## wim (Feb 28, 2005)

bernithebiker said:


> It just surprises me that there isn't an aero road frame out there (not TT) that sells you a special bottle WITH the frame that mimics the shape of the downtube so smoothing air flow.


Cervelo claims zero drag penalty with an Arundel aero bottle on the S5 downtube, so at least they give you a hint which bottle they used in their wind tunnel testing.


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## trailrunner68 (Apr 23, 2011)

Just go without water, dude. Having a bike that looks fast is more important than carrying the stuff that will make you fast. By the time you are thirsty, you will be at the coffee shop.


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## AdamM (Jul 9, 2008)

Unless its a 40k or longer do you really need to carry a water bottle?


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## danl1 (Jul 23, 2005)

Somebody made a Camelback joke; it's actually a really good answer. The models they design for it are said to improve the aerodynamics of the body, which is the largest source of drag by far.

I've wondered how a horizontal bottle under (or above) the top tube would test out.


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## Kerry Irons (Feb 25, 2002)

*Need?*



AdamM said:


> Unless its a 40k or longer do you really need to carry a water bottle?


I don't know - how about if it is the middle of the day, 100F (38C), and high humidity? What do you think?


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## andresmuro (Dec 11, 2007)

bernithebiker said:


> OK, so you've just bought your dream aero road bike.
> 
> Hours of wind tunnel testing, graphs that show it to be better than any other aero frame out there, a sexy video with soft lighting and pumping music. Free speed. Fantastic.
> 
> ...


Water bottles have little effect. some people tie them under the aero bars. However, there is little evidence that a water bottle in the downtube or seattube will affect aerodynamics. In fact, there was one study that said that the round bottles had little effect on aerodynamics. 

As long as you can get low and narrow, with a good aero position, without loosing power, you are doing great. That's what a good aero frame should help you achieve. High profile wheels should also help a bit.


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## INeedGears (Aug 23, 2011)

I wonder what impact the non-aero dynamic rider sitting on top of the aero bike will have. Oh man, everyone on an aero bike better start using TT helmets. 

Sorry for the sarcasm but if the aerodynamic look is that important on a training ride then by all means buy an aero bottle. On race day, nobody is using an aero bottle so there is no advantage. If you're talking about a TT bike the odds are your time trial is short enough that the aerodynamics of the bottle will have neglible impact either way and if you like triathlons the rules aren't the same.


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