So I have a road bike, with STI shifters, but I'm looking to do an Iron Man. I've done centuries before on the bike just staying on the low bars, but I've found that the swim is just so exhausting for my arms and shoulders that I really need to go to aerobars.
I wanted to just get a new base bar with integrated aerobars so I wouldn't be carrying the extra weight of my roadbike handlebars. What's involved in that though?
I'm assuming that I'd need to replace my shifters?
I'm looking for aggressive posture, but I'm assuming this will require my handlebars to come with a fair amount of padding given the duration?
The Ironman I'm doing is very flat, should that play into my selection at all?
You're going to need a lot of stuff to make this change.
Bar end shifters for the ends of your aero bars.
Bar end brake levers for the ends of your base bar.
Base bar & aero bars or an integrated option.
Potentially a new seatpost.
Potentially a new stem.
Maybe a new seat.
You might want to look into clip-on aerobars. These attach to your existing bars and typically have a slightly less extreme position so you should be able to get away without too much of the extra fit stuff above. This'll give you a chance to see if you even want to use areobars, they're not for everyone.
You're also going to want to get a good amount of training in in your new position, if your event's less than a month away, I'd be wary of making this change now.