Here is an illustration of the 19" Kibo Dirt Drop (with quill stem) with an estimated saddle height of 617mm based on a height of 5' 1". As you can see the 19" Kibo DD with quill is likely to be too big assuming an inside leg measurement of 699cm (27.5") - the standover height of the bike will be circa 4-5cm taller than your inside leg - so you may want to consider either the ahead version of the 19" Kibo DD which has a sloping top tube giving a lower standover height, or we can discuss bespoke geometry of this frame based on your specific measurements - we would recommend a sloping top tube with a specific angle providing you with some standover clearance based on your inside leg length. Please email us on firstname.lastname@example.org to discuss.
To measure your inside leg: 1. Get a book and stand with your back against the wall, 2. Place the book in between your legs as high as it will go, 3. Move away from the wall keeping the book against the wall and finally, 4. measure from the top of the book to the floor. It will also be useful to measure the saddle height (bottom bracket centre to the top of the saddle) on your current bike and compare it against the illustrations.
We look forward to designing a bespoke Kibo Dirt Drop for you.