What are your thoughts of John Cobb’s research in 2003 showing that a water bottle on the downtube and the Profile aero front bottle is the best for aero results?
http://www.slowtwitch.com/mainheadings/techctr/waterbottles.html
Better than behind systems, etc…
Did he have a big inventory of them when the study was done?
**<u>Ave. Drag 40 km 112 mi </u>**
base bike, no bottles 7.537 1:07:26 5:56:48
down tube bottle only 7.370 1:06:58 5:54:29
seat tube bottle only 7.433 1:07:09 5:55:22
bottles on both tubes 7.598 1:07:36 5:57:38
Profile bottle only 7.337 1:06:53 5:54:01
Hydropac w/40oz. only 7.556 1:07:29 5:57:01
Never Reach only 7.561 1:07:30 5:57:07
behind-seat low bottles 7.658 1:07:45 5:58:27
behind-seat high bottles 7.578 1:07:32 5:57:27
the problem with the behind-the-seat systems was that they were too tall, for the most part. As long as they are lower than your butt, they’re a wash drag-wise. A single bottle mounted to the seatpost so that it is below the slope of your back is best.
I would think you’re right, but if you read this study it says otherwise…they tested both behind bottle cages…
I have another question with all this data stemming from what I saw this year on the Tour team time trial.
Maybe half of the teams had bottle cages on the seat tube bosses (eg, Discovery, Lampre, Euskatel) during the TTT. But the Cobb article suggests that the downtube is better.
What is up with that?
harp
Clarence,
Although I don’t disagree with that study and the numbers presented, I believe it is frequently misused and misapplied BECAUSE that study was limited to THAT bike under THOSE circumstances and is NOT universal in application. So (and you certainly did not do it) we can’t say in blanket terms that bottles on the frame are more aero than than being behind the seat (which is what we genarally see as the interpretation). Also, for me, I have to change my pedal cadence and stride when using a frame mounted bottle and I don’t w/ behind the seat bottles.
I would rather have liquids at the ready then worry about a small increase in drag.
Proper hydration outweighs any negative effects of using a bottle while racing.
For under 40k events, little if any race hydration is required, bottle drag is highly dependent on the rider’s position.
Choose whichever system is easiest and most convenient to use.
Personally, I use no hydration for races under 30k and depending on the heat, I might use a bottle or camelbak bladder under the skinsuit for 40k TT events. Otherwise I just pre hydrate extensively.
What is your 40k TT PB?
i have one of these coming what do you think? i had the Campy Aero’s back in the 90’s but this should be much faster.
dan…
I’m with Gary Tingley on this one. I use Neverreach, because I can stay aero, and take liquid frequently in small doses (so I don’t cough it back out…). That for me trumps drag, which I’m not sure I believe is higher for the Neverreach design anyway…
How much drag is caused by swinging your arm around, and taking a swig? How much less efficiently are you pedalling while you’re doing this?? Hmmm…
On the downside, the Neverreach swings about like a pendulum if you like to throw the bike from side to side climbing aggressively or sprinting. Only a problem for me if I’m ‘playing’ with my roadie buddies when I’m on my tri bike though… 
Here’s a question – is it possible to rig, or does there already exist, a water bottle to be mounted on the downtube cage with tubing and a mouthpiece? Wouldn’t that give you the “best of both worlds” – aero qualities of the downtube bottle mount and the ease of the NeverReach tubing? Or would it just be too hard to draw the liquid upward that much?
OK, that was more than one question, I know…
I’m with Gary Tingley on this one. I use Neverreach, because I can stay aero, and take liquid frequently in small doses (so I don’t cough it back out…). That for me trumps drag, which I’m not sure I believe is higher for the Neverreach design anyway…
How much drag is caused by swinging your arm around, and taking a swig? How much less efficiently are you pedalling while you’re doing this?? Hmmm…
On the downside, the Neverreach swings about like a pendulum if you like to throw the bike from side to side climbing aggressively or sprinting. Only a problem for me if I’m ‘playing’ with my roadie buddies when I’m on my tri bike though…
I am with you on this. The advantage of any system is not how heavy or light it is or how “aerodynamic” it is or is not but how much it helps the engine. The advantages of the NR system for longer distances seem obvious if the rider is able to stay in the aero position and still get the optimum fluids. Other systems (which hold less) may work just as well for shorter distances.
Remember the old “Bikestream” one. If I remember right it was a neoprene case stretched between your seat rails and two zip-ties on the seatstays. Inside was a real thick walled bladder that looked like a blood pressure pumping thing. The mouthpiece up front had a spring loaded checkvalve and the system came with a huge pump thing that was like the things they pump snowcone syrup out of.
Was driving a support van for a paraplegic competitior at the Roadrunner Half in Vegas (1991?) when his exploded in his face right out of T1. He kept going covered in a couple quarts of Excel…fun…what a stud.
Michael
I like the Podium Quest with its double bottle and two straws between the aerobars. I mix a super concentrate in one tank and add water in the aid stations to the other. Then sip on both straws to mix my sport drink. With this system there’s no need to carry any other bottles.
Big plus of this is can stay aero when drinking, can change concentration by sippling more or less water with concentrate, and it is easy to refill without stopping.
A potential downside is that the weight of the two bottles is high and in front which could effect handling.
I am not an aerodymanics expert but I disagree with the above. The problem with the behind the seat systems is not the actual airbrake like drag created, but the amount of turbulence that they introduce into the airstream. You have this wonderfully smooth flowing river of air that suddenly hits a “rock” just as the two streams meet. Think of two streams that flow together to be come one, then go park your Ford Expedition right at the point the flows meet. Think you are gonna get some waves? Same thing happens here, you are interupting the smooth passage of the airstream around your torso by sticking something into the air flow. Bottle on the down tube is in a spot that is A) already somewhat blocked by the fork, front wheel, headtube, etc. And B) Widens the airflow slightly, shielding the rear wheel similiar to the rear cutout concept.
Now I realize these are gross generalizations. But my point is that aerodynamics is not just about presenting a smooth surface to the headwind, but smoothing the entire airflow, allowing the rider to slip through with a minium of effort. If you look at when the auto companies really started to pay attention to airflow. You look at the first Ford Tauruses and Mercury Sables. Everyone thought the rounded backends looked weird. Same concept here, smooth the entire airflow.
Oh well, I’ve pratteled on enough…asbestos undies?..check…Flame On Dudes.
The Minoura single bottle carrier solved that problem by putting the bottle essentially between the legs, behind the seatpost and below the butt. No problems with disturbing the laminar flow that comes off the back (which I’d argue is pretty turbulent, but I’ll go with it anyway).
The Minoura single bottle carrier solved that problem by putting the bottle essentially between the legs, behind the seatpost and below the butt. No problems with disturbing the laminar flow that comes off the back (which I’d argue is pretty turbulent, but I’ll go with it anyway).