Originally Posted by
unterhausen
why would you want a lot of extra space under the DT? It could possibly look goofy. I suggest learing how to use a frame specific cad program. I use bikecad, and it's great. There is also rattlecad, which seems to be really nice too. So far the big advantage of bikecad is the number of pre-defined parts.
This will not really affect stiffness in a way that matters while riding. The top/down tube spacing can affect the stiffness against braking forces if it's too small. On a small frame, you want to avoid overlapping the top tube and down tube. Bikes like that have a higher failure rate from what I have seen.
This question actually came from me using bikecad as you can choose how much past the top tube and down tube you want the head tube to extend. I agree it could look goofy if it goes to an extreme.
Just wasnt sure if some here do something like always have 15mm of space below the down tube or always have 25mm of space- etc etc, and why they decided on that.