Originally Posted by
himespau
I've wondered about how sizing converts as well. Been thinking about building up a townie for my wife so she'll have a bike that's worth riding on her occasional commutes (and maybe if she's got something nicer than her x-mart special that she's had forever and hates, she'll go riding with me occasionally). The question of how reach changes when you're sitting upright with bars that sweep back and are at/above saddle height (and how to achieve that), are things I've been thinking about. The fact that I'm trying to figure out how to do it on a step-through/mixte frame for my 6' tall wife is another complicating issue due to rareness of frames, but, as with you, I'd love to know how fit converts over.
Not having ridden a bike like this in many years, top tube length is what I'm having trouble wrapping my head around. Using the swept back bars considerably shortens the reach, which is a good thing if you want to be upright and comfortable. Eyeballing my road frames and imagining some comfort bars on there, the reach looks really short to me, which makes me think a longer top tube is in order, especially if you plan on ever having to stand to climb a hill. On the other hand, to much reach will force you to lean too far farward, undermining the "comfort" factor.