I definitely can drink 40 ounces per hour when it's HOT! I did a sweat rate test to make sure I wasn't over drinking, and I was not.
I have a "fuel box", which is a little case that velcros to my top tube. It can hold maybe 6 Gu's, just right for a 1/2 iron race. Sometimes, I also stuff things into my tri top bra. Tho, the sharp corners of a Gu packet can cause major chaffing if left there too long.
I use NUUN for electrolytes. It's a small tablet that you drop into your water and it dissolves quickly. It has no calories, just electrolytes. I use 1/2 tablet per 20 ounce water. I have trained using 1/2 NUUN per 20 ounces of water, and Gu every 30 minutes all season, and this feels right for me. I think I am actually drinking less water now that I am using electrolytes. I need to do another sweat rate test.
(I used to just use water with a pinch of salt added, and Gu. This left me craving salt for days after long workouts
).
I have an aerobottle, and two bottle cages. That will allow me to carry 60 ounces of water. I'll have those pre-laced with the NUUN. I'll carry a few extra NUUN's in my fuel box, in case I need to refill my water. I don't mind going thru the water bottle handoffs.
This is my strategy, which I tested in a recent olympic race. I have yet to finish a 1/2 iron feeling "strong", so take this with a grain of salt!
Nutrition:
* dinner night before early at 4:30. pasta and small chicken breast.
* whey smoothie at bedtime
* 3 hours before race: peanut butter and jelly sandwich on white bread
* 45 minutes before:Gu
* Right Before: Gu
* T1:Boost. Go easy on bike for 20 minutes to let this settle.
* Every 30 minutes on bike: Gu
* T2: Boost
* Every 30 minutes on run: Gu, last one Expresso flavor with 2x caffeine
Hydration:
* 20 ounces of water in my aero bottle with 1/2 NUUN tablet
* 20 ounces of water in both bike cages with 1/2 NUUN tablet, to refill aero bottle
* spare NUUN tablets, already split in half, in case I need more water at the hand-off
* 20 ounces of water with 1/2 NUUN tablet in my palm holder for the run.
* Carry a tube of NUUN with tablets already split in half in my left hand, to refill water on the run.