Since they were used as bikeshare bikes, these are meant to accommodate most adult riders. Through experience, it seems 5′ 3″ is the shortest comfortable ride and 6′ 5″ is the tallest. My personal suggested inseam is 28″ to 35″. I have sold bikes to shorter kiddos that were comfortable hopping on and off the seat when stopping if their feet didn’t touch the ground, since there is no bar in the middle.