At least on my wife's S22 there is only one set of bosses to which to attach a water bottle cage (on the seattube). It's probably the same on on all the sizes though, because it'd be pretty tough to install them on the trailing edge of the aero down tube. You should be able to fit a 24oz bottle no problem. If you need more water get a Jetstream aero bottle or some back of the saddle bottle cages or both.

i've got a size 60 s25 and it's only got the setup for 1 bottle. i can fit a big bottle no problem

Nope...mine are behind my seat.

There are water bosses on the seat tube, but not the downtube (if I remember correctly).

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TheBikeRacer.com

I have a 2005 S22 and it has one cage but will hold a full size bottle. I also put a holder behind my seat that will hold 2 bottles.

Here's a couple of pics: