Do you guys have a trick to combat this? In my last two half ironmans i realized I was getting a lot of air in my stomach, I think in large part from the aero bottle straw.
Thanks,
Dan
www.aiatriathlon.com
What are you drinking? The only time I have had problems is when using Accelerade.
I think that was the protein on a warm day.
this has happened with infinit, regular gatorade, and heed.
Are the two straws snug together. You can suck in air where the straws join if they aren’t snug.
Also, if the straw is too long it can be a bear to suck the fluid that high up and your increased suction might cause air to leak between the straw and your mouth and then be swallowed.
You should go to McDonalds and practice with a large chocolate shake. 
Come to think of it, a big mac and fries would probably go good with that…
I had the same problem. Perhaps my straw was too long and I was catching air when pulling up fluids.
At Rockman, I ditched the aero bottle and went with regular bottles. It just seems easier to squeeze fluids out of a bottle, rather than having to suck it out of a straw.
If there’s a way to avoid this, I’ll give it another try.
I had this issue and it actually went further into throwing up on the bike. I was using carbopro and nuun. I have since ditched the carbopro, nuun and aero bottle. I have found GU2O and H2O in my regular bottles to be the best for me.
You are not alone.
I’m glad it’s not just me. I just recently got a tri bike and used an aero bottle for a few weeks and my first race on it. I had to sit up a few times just to be able to burp. Got a behind the seat thing for regular bottles. Going to try that next.