You must mean the seat tube because there is no derailleur clamp on the down tube. Are you saying the holder bolts on just fine but the pump won't go into it, or that the mount doesn't go on because the clamp gets in the way? If the latter, you might have to cut away some of the material on the mount. I don't have the Road Morph, but I have a different pump mounted the same way and I had to cut part of the middle section away to clear the clamp.