I want to get a bag that goes between the top tube and the diagonal tube, to carry extra clothing on long rides. It needs to be light and it needs to have enough room at least for a light cycling jacket and leg warmers.
The problem is that I don't have a whole lot of room there. I used to have a 52cm frame and squeezing a bag in there simply did not look possible. I recently went up to 54cm and it got a little better. I have about 6" from the top of the bottle to the head tube. Most of that space is needed to get the bottle in and out.
I'm wondering if anyone has this kind of setup. What bag do you use, and do you use a regular bottle cage, or did you get something special to keep it from interfering with the bag?