Many riders at all levels are going to shorter cranks anyway. I'm not one of them, but I won't argue. Eddy and I have about the same leg length, 89 cm. Eddy used 175s and that's what I've gotten used to. I think my position is a little better with that length and I appreciate the leverage when climbing. Miguel Indurain, who was taller, used 180s. I don't think you'll gain anything by going longer than 180 or 177.5.