I am in the process of trying to adjust my road bike to a Tri bike and I am having a lot of trouble finding a seatpost that is both long and has enough forward offset. I need at least 30mm forward offset and I need at least a 350mm post. If possible I would like a 31.6 but I am willing to shim a 27.2 up to 31.6 if that is my only option. I can find short posts with enough offset or long posts with only a little offset, but can't find something with both.

I have looked at setback posts and then spinning it around but I don't know which ones besides the Thomson is actually reversable. Although the Thomson is nice...16mm of offset just isn't going to get me where I need to be.

Does anyone have any experience with posts that may work?