SO during lunch today after enjoying yet even more leftover turkey I decided to give it a go. There are a lot of differant rear hydration system out there of varying cost etc, but I'm a simplistic type person, I don't want one that carries 6 water bottles, 7 tubes, and 14 CO2 cartridges. Ok, so that's an exagerartion. I'm only wanting one rear bottle to go with the one on the bars.
I'm not yet decided if I will run on on my downtube for IMAZ next year, but I have a lot of time to decide, I did my HIM this year with only 2 bottles and it was fine, thinking the same will be true for IMAZ.
None the less here it is, no step by step pictures since I only had about 15 min. Basically it is an aluminum cage, I bent the top mounting hole out to go under the seat, and the bottom mount in so it wouldn't be as blount of a metal cage on carbon seat tube scrathing problem.
I couldn't bend the inward one in too far though as I had to leave room for the bottle to go in.
I ended up not mounting as high as I wanted so the tab I bent out didn't go up under the saddle, also I added a 3/4" strip of carboard on the bottom of the cage to also prevent the metal on carbo scratching. I will try something else late, maybe some type of rubber coating.
I used 3 heavy duty zipp ties to secure it. 2 on the top to the seat rails, and 1 on the bottom around the seat tube. Intial test, it feels plenty sturdy, but the bottle is a tad low, I have to stretch down to get it, but not much, I can live with it and still stay aero to get it. I do like it being low as it is easy to step over. I will try it as intially planned 3/4" higher with the tab under the seat, and that should help.