The saddle is another good spot to put hydration or storage pods, as recent independent testing has shown that if you do it right, it's basically aerodynamically neutral. Now, there are LOTS of products made for this category, but I think a lot of them are rather overbuilt, overly large, and just lead triathletes to carrying WAY too much stuff behind the seat. This can lead to a very bloated setup that is anything BUT aerodynamically neutral. So as we go through this page, remember to keep things simple!
For most places on the bike, cage selection isn't critical - any decent cage will keep your bottles in place. Saddle-mounted bottles are different, because of their propensity to launch bottles! So if you want a rear bottle, cage selection is critical, and the difference between cages can be quite large. The best cages have a solid lip that fits into the bottle's choke point, as well as strong arms that wrap the bottle well. I have found that I get the best results with XLAB's Gorilla XT. It launches bottles less than any other cage I have tested. We'll talk more about various cages and mounts on the next page, but for saddle-mount purposes, the XLAB Gorilla XT should be your first and last stop. They're pricey, but absolutely worth the money. If you are looking for something less expensive, try the Specialized Rib Cage. They aren't nearly as effective as the Gorilla XT, and can still launch bottles, but are worth considering if you are on a tight budget.
The most aerodynamic saddle bottle setup will be a single bottle Chris Lieto style, right behind the saddle. You can do this with zip ties for the el cheapo solution (that's how Chris does it). Zip ties weigh next to nothing, and can easily be removed if you want to tweak your setup.
If you have a newer bike or saddle, there may be some options worth considering. Several Quintana Roo and older Cervelo P2/P3/P4 models have a 2 hole pattern on the seat post that can be used to attach a rear mount like the Delta 300 from XLAB. If you have a Ritchey seat post clamp, there are also some direct mount options like the Delta Sonic mount from XLAB. This is the type of clamp found on the Scott Plasma, newer Cervelo P2 / P3 / P5, Kestrel, Fuji, etc. There are several saddles which include bottle mounting options on the saddle itself (Specialized Sitero, Dash TT9, etc).
If you don't want to go the DIY route and your saddle / seat post won't allow for direct mounting of a cage, there are many solutions on the market that allow you to add a saddle bottle. Speedfil, Profile Design, XLAB, Specialized, Beaker Concepts, etc. all make mounts that are quite similar. Aside from price, the main differences between these various products will be the number of bottles that can be carried (1 bottle, 2 bottles, or either 1 or 2 bottles), material (alloy, plastic, carbon), adjustability, weight, and ability to carry other accessories (CO2, storage bags, etc.). There is no clear best product, but a lot of good choices. In general, I prefer to stick to a single cage, mounted close to the saddle. Skip the enormous contraptions that have parts sticking out of every surface. I have linked to some of our past reviews below.
Read more on Saddle Bottles:
- Review: Dash Cycles TT9
- Review: Specialized Sitero
- Review: BC Blaze Bottle Holder
- Review: Specialized Reserve Rack
For longer training rides, using standard cages on the down tube / seat tube can be quite convenient. But I don't recommend leaving them there on race day. There are other good places to put round bottles (BTA or behind the saddle). Recent data on modern frames (from Cervelo and others) suggests that round bottles are a bad choice for frame mounted hydration. They can create quite a bit of drag, and should be a last resort if none of the other options in this article work for you.
If you decide that you absolutely need to put a bottle on your frame, an aero bottle is preferable to a round one. Specialized, Arundel, Bontrager, and Profile Design all make good aero bottles, but some of them integrate better with certain frames than others. If you have a Specialized bike, get the Specialized Virtue bottle and mount it on the downtube. If you have a Trek, get the Bontrager and mount it on the seat tube (it fits better there).
In some rare cases, picking the right aero frame bottle can lead to a solution that's probably almost as good as an integrated one. For example, when I reviewed the DengFu FM086, I found that the TorHans VR bottle was virtually a perfect match. In that case, I'm all for leaving it on all the time, as a permanent storage box or as a concentrated nutrition spot on race day. But again, finding such a good match is rare. The general rule is that if you're using an aero frame bottle, try to put it where it better "completes" the shape of your bike without leaving gaps. Otherwise, try to leave your frame bare, so its aerodynamics can work as designed. In short, the frame bottle should be your last stop, or last resort, for finding a good hydration solution.