I am building up a road bike for my partner. She has been riding a modified road bike (flat bars) which had an very upright position. Question: On the new build, should I start with a more aggressive position and, if neccesary, gradually work towards more of a "comfort' fit or should I start with the more upright position and work towards a more aggressive fit? I should note that she is fairly flexible (yoga teacher).

Ask her....

I did. She replied: " I don't know, whatever you think".

I guess, I am wondering what is the typical starting point. Level with the seat and go from there?

Yes. Leave lots of room to move the stem up and down. In other words, don't trim the fork so much that you reduce options.

Start closer to what she's used to, and move the bars down as she gets comfortable. Don't push her if she's not interested in going fast.

Too late

Already seems disinterested. Sell her on ebay or CL and upgrade.

Wonderful thing about bike is when you get rid of them, they don't take half your **** with them.

Set it up so that the hands-on-hoods position is close to the bar height and reach she's used to. Let her explore the drops and other hand positions herself and see what she likes.

BL