Athletic tops for the well-endowed take some (expensive) trial and error. Do you wear 2 jogbras when you run? If that works for you, a similar approach may work for the tri. I wear a Sugoi Fizz bra (which you can swim in) underneath a Zoot tri top that has a built-in shelf bra. The combo is adequate for my 34DD's and doesn't chafe. The Fizz bra especially has a the best rib-band (whatever they're called) of any of my sports bras - really stays in place. The main thing is to wear a bra (and top) of seam-free wicking material for the tri - you'll be running around wet and all that. I don't think something like an Enell would work for a tri, too restrictive and heavy. I swim in my Fizz bra/tri top combo, as well as bike and run.