Active Toby,

That pretty cool, which 1/2 IM are you doing? How tall are you and what frame size do you have? The only tip I have is that to make sure when in the aero position your arms(biceps) are perpendicular to the ground and you fore arms are parrallel, if you're too stretched out, then you will negate some of the benefits of the aero bars by over using your shoulders for support. If you're too crunched up, your breathing will suffer due to your legs compressing your abdomen during the 2nd 1/2 of the upstroke phase and beginning of the power phase. 1 more question, what kind of bars did you get?

-Anthony

Active Toby,

A forward facing seat post would be a great idea, taking in to account the info you provided.  It sounds like you have bike frame that may range from just right to very slighty too large, which is fine, riding styles and comfort level are different from bike to bike, as well as the individual.  I have a road bike that is a 59cm and I am 6'2".  In my situation, which is similar to yours, would also call for a retro fitted seat post to accomodate a more accurate fit that resembles conventional tri geometry.  I opted for an entry level tri bike(felt S-32), due to a killer deal(50% off), other wise I was going to do exactly the same as you are.   Good choice of bars, I am very happy with all of my profile design equipment.

-Anthony

I just came across this thread and wanted to comment that the advice offered here is awesome!  Keep it simple and try each bike modification before moving onto another.  I made small modifications to my Giant OCR-1 that have resulted in what I feel is a great ride.  My first change was some profile aero bars, then a new Ritchey stem and finally a new seat post.  I would highly recommend working with a local bike shop with experience in fitting bikes - this will save you time, energy and if they are a good crew you will learn a lot.  Small changes to you set up can reap you big rewards in comfort and performance. 

Good luck and have fun!