you obviously don't need to get into that position while riding, but doing this stretch will give a pretty good indication of the range in your hip flexors. having flexibility there is what allows you to sit comfortably with your bars well below your seat, with your hips rotated forward and your legs still able to generate good power.

I can do the stretch to where my wrist is past my foot and I can even double over like the pro in Euro's pic, but I still have bars only about 2" below the seat.

[edit] btw, even though I can double over like Rujano, "good power" for me while riding is probably equivalent to what he generates while stretching!