I used a thin aluminum foil around the seatpost to fix that issue. Please email Charlie at Body Float and tell him. He did not believe it when I told him.
The OD for BF is tiny bit smaller than the ST2 seatpost.
Finish Line makes a product called Fiber Grip. Comes in a small tube (and not expensive). Use generously inside the seat tube and then install seatpost, tighten to spec, and your seatpost will not move. Whenever you remove or adjust the seat, relube. Works like a charm for me and I am morbidly obese. My local shop will not install a seatpost without it.
My St2 seat post did the same thing Jonah. Graphite paste was what stopped mine sliding down. Park Tools or any quality shop will have some . Congrats on getting an St2 . Mine is running better with these cooler temps. were having.
Same issue with my ST1 seatpost. Use assembly compound for carbon: it contains grains. Apply on the inside of the seat tube before installing the seatpost. Because of the grains in the compound, the seatpost will not slip down.
I bought Park Tool Supergrip Carbon and Alloy Assembly Compound
and used it on my 2 regular bikes and the Stromer (all have seat posts that slip, some faster than others). I look forward to seeing if the product works. More to follow.