>>1798257Because leaving out the top tube requires changes to the geometry of the frame that makes the bike ride like a barge: steady and true but lumbering and slow. On my Cross Check, I feel like I'm steering the bike almost as much with my hips as I do with the bars. Compared to that, my aunts town bike feels like a block of cement with wheels.
Mixte bikes mitigate this problem somewhat, but then again they are not truly top tube-less, they just have their top tubes moved further down, which is really just a slightly more extreme version of the sloping top tube found on most modern mtbs (including the one in your pic).
Bottom line is that when discussing this type of stuff, you have to maintain a more holistic view of frame geo. Minute changes can make a huge difference in handling and comfort.
