I have not the slightest idea how to go about fixing this, or even if it is fixable.
I also question whether it is my fault, not using my seat properly or if it is just that he has a very rough transition. I hate it! Its awful and so uncomfortable. I can't imagine it feels good on his back either when I start bumping around, but it really just throws me out of any kind of decent seat position.
Ex: We are trotting up a nice hill, nice and smooth, listening well.. so hey, lets lope for a bit. We lope for a bit. Now his loping is not any where near collected, so I bet that doesn't help either. Ask him to slow down, he is real slow about it, and then eventually we go to this awful bouncy trot. He already has an awfully bouncy trot, but this is just horrid.
Now that I think about it, I think there is more that needs work than this downward transition. There is not collection at the lope, and most of the time its fairly out of control. Usually he goes a lot faster than I would like.
Ahh! This whole learning by yourself thing Sucks.