Lots of option exist on tri bikes for bottle placement.
I have certain limitations with my set up, so keep that in mind as I list the options I have.
After reading these, please give me your opinion and reasons behind it.
Lynskey custom tri bike with a very conservative aero layout (old man with a bad neck :-)). The tubing is nicely tapered and more aero than simple round tubing and I have a very aero carbon alpha Q fork. There is no rear wheel cutout. Thus, it is moderately aero , as tri bikes go. I do have 60mm rims and an aero helmet.
I need to carry two bottles. I can do so by:
Using the traditional placement of cages in frame triangle
Using one of those and using an aero bottle and straw between the aerobars.
Could put one behind the saddle and an aero bottle and straw between the aerobars.
Could place two bottles behind the saddle
Could use a Speedfill on the down tube, and regular bottle cage on seat tube.
Could use a Speedfill on the down tube and one bottle behind the saddle.
The following things are my concerns, having read about this stuff for years and still not knowing what to believe:
I hear conflicting info on using traditonal bottle set-up. One theory is that they are simply the widest, least aero set-up, while others suggest that bottles inside the frame triangle fill that void, like a disk wheel, deep rim or a fairing, even. Particulalry if use two 24oz bottles to fill most of the space.
Another factor is that filled aero bottles between aero bars make for squirrely handling due to the added weight on the front end.
Lastly, as much as I see it on the race course, I have heard that rear mounted (behind the saddle) bottle set-ups destroy any aero effect you have acheived with your positioning because they creat an eddy-current between the bottles, the saddle and your butt.
I suspect this is just splitting hairs for someone only going 18-20 on a rolling IM course, but since I have some options option, why not hedge my bet.
Behind your butt is supposed to fill the eddy area created by your body, making it even more aero.
Don’t just consider most aero. Also consider the easiest grab/fueling without disrupting your pedaling or causing handling problems. Whatever keeps you in the aero position, pedaling, and safe is going to lead to best results. This can vary by person, so be willing to modify and you’ll be happiest.
I echo the advice on “consider more than aero.” It doesn’t help you if you can’t reach it.
There is some good research posted by our engineers here.
Someone did a study on bottles and frames and found that the right answer is “it depends”
The following is from memory.
- seat or downtube bottle depends on frame. Some frames seattube, some frames downtube. Best is to try and fill the corner as low as possible at the BB.
- bottle behind saddle depends on how close to your glutes the bottles are. This depends on the mount, but also on how far back on the saddle you sit, and how big the bottles are.
- bottle between the aerobars is usually good – except if you have a straw sticking straight up.
- bottle horizontal between the aerobars is good if it fills your arms, bad if it’s above or below.
In other words: take it to a wind tunnel, or try to use the bottle so that it fills a gap; don’t create a gap.
I don’t like bottles behind the seat because they tend to bounce out – especially on cobbles. I like all my bottles to be the same shape so that I can swap them when they’re empty. That way I can always easily reach a full bottle. I like to use good bottles – especially if they’re horizontal – so that they don’t leak.
It’s all a bit of a compromise.
My bike frame is too small, so I actually have to use the small bottles. Large ones don’t fit. I use 3 for an Ironman distance. One horizontal between my arms, one on the seat tube, and one on the down tube. All bottles are round. (my bike still has round tubes.)
Just go for broke and use one of those two-beer-can construction helmets you see the spectators use, and put your water bottles on your head 
(are construction helmets legal in tri?)
… and David Byer is the “someone” who did the study I mentioned.
… and that study shows that at least one “from memory” point was totally wrong…
Why do you need two bottles? I’m not suggesting you don’t need them both, but why you need them could make a difference. I train with three bottles. I race with two. In training I use a bottle between my arms (no straws please, just a regular bottle), a bottle behind my seat and a Bontrager aero bottle on the seat tube which fills ithe triangle nicely. For racing I drop the bottle behind the seat because it is too hard to get too and I have to use rubber bands to insure it doesn’t catapult out.
My bottle between the arms is just water. The aero bottle is nutrition. The reason I asked why you needed two was really to determine the need to refil them both. My nutrition bottle does not need to be refilled at all, except in a full IM, which I can do easily at special needs. Otherwise, it is not quick to refill and I would not want to have to mess with it while rolling through an aid station. The bottle between my arms gets tossed at the first aid station and replaced with a plane water bottle from there out. In training, of course, I have no volunteers manning the aid stations so I just stop and fill both my water bottles back up if my ride is sufficiently long.
So I suggest aero bottle on the seat tube or down tube plus a bottle between your arms. If it is a short race where I will take little or no nutrition, I keep the aero bottle in place on the seat tube, I just don’t put anything in it.
Food for thought.
David (and everyone),
Thanks for the replies. I do have one question about “the straw”. Given that your study didnt like the drag effect of a straw, it begs the question: How much aero advantage are you getting in a real world setting with a horizontal bottle, when you have to take your hand off the bar, grab the bottle and contort either your drinking arm or your head in order to drink? All the while, a straw system, albeit adding a bit more static drag, allows for very little head movement while drinking AND your doing it hands free. Less turbulence. So, we have two situ’s: constant drag created by the straw in exchange for static aero posiion while drinking and uber convenience, or superior aero dynamics as long as you dont drink, but a potentially huge parachute effect each time you drink. Does my inquiry make sense? I think I see where this may be going. In cases where hydration is less critical, a.k.a. sprint-oly distance, you opt for horizontal bottle. In long course, you opt for whtever will insure that you’ll drink enough.
OK, let me have it !
David (and everyone),
it begs the question: How much aero advantage are you getting in a real world setting with a horizontal bottle, when you have to take your hand off the bar, grab the bottle and contort either your drinking arm or your head in order to drink?
Great question! It does make sense to ask. Frankly, we have no study of that comparison. In fact, it would be very difficult to execute a study with so many variables involved. However, if we are talking real world situations, we should take everything into account.
First; does any athlete ride without needing to break their aero tuck at some point during a tri, be it OLY, HIM, IM or whatever distance? I think most people need a break from the saddle or arm rest, even for a couple of seconds, for the sake of comfort and focus. Most athletes that we spoke with take this break and drink/eat at the same time.
Second, with the aero bottle between the arms, you don’t really have to come out of the aero bars to drink. It’s a relatively small movement to swing the bottle out and tip it up toward your mouth as long as you are willing to suck on the nozzle like you would from a straw. Now, I can’t claim to race super long distances so I usually just leave the bottle off altogether, but I have watched a couple of athletes do this on rides. I’m sure it takes a couple of practice runs but pretty simple.
Finally, the bottle between the arms isn’t just saving the constant drag created by the straw; it can potentially lower your overall drag compared to riding with no bottle and no straw if position properly. Pretty cool.
Damn it :-). 25 years of laying down on aero bars and NOW I have to learn a new trick?! Okay, so while I monopolize your time. Lets talk about the rear saddle cages and bottles. Your study concluded that we want the bottles as close to the saddle/butt and as narrow as possible. Done. Now, what about height? I assume, that we do NOT want them riding high, so as the creat a v-shape (if viewing from the side) between the bottles and the body. That, lower is better, to create a smooth line from my lumabr sacral area to the bottle tops, or better still, tucked nicely under the back half of the saddle. Yes?
Good lord, I have gone from years of being a weight weenie to an aero nerd. I am not shaving my gotee!!!
nature’s pocket… always the answer for “where to put” something in triathlon.
Too low creates drag, too high creates drag. So, the answer is “just right”… ha. I think the best place is generally right in the ‘wake’ of the body. The best way to determine that is with a wind tunnel. With the ‘wind tunnel of the eye’, try to get the bottles as ‘behind’ your body as possible given that you will still be able to reach them.
Clear as mud?
See Thread above…one round bottle on down tube!
Yes. Makes sense. Thanks for your time.