Purchase smaller road bike to use for tri?

[bartturner]

I am right between a 56cm and 58cm for a road bike. I am closer to a 58cm then the 56cm. I am thinking about buying the 56cm bike and it will be easier to setup for doing triathalons. I am new to all of this. But I am thinking that when adding aero bars the geometry will be better.

Thanks for any help. It is very appreciated.

[Snicklefritz]

Are you buying used or planning to get something from a shop? If you are serious about Tri and/or going to spend more than a small amount of coin, I'd get fitted properly.

[bartturner]

I am buying the bike new. But it is mail order.