I am having a small issue with the seatpost and the expander/wedge.
I just realized that crank arm length, cleat system, sole height, and certainly the saddle rail-to-top are the determining factors for the seatpost insertion depth.
I've cut my seatpost a bit shorter than my target saddle height because I miscalculated the insertion depth -- it's primarily because I used 165mm crank instead of my usual 170mm. It became an issue as the seatpost is slipping on every ride even with reasonable tightening on the expander. I haven't applied carbon paste though.
After I checked the seatpost, I noticed that the contact area of the expander to the seatpost is too small. The contacts are mostly on the edges. Each slippage, the expander digs into the seatpost leaving two parallel scratch lines along the seatpost.
The solution should be to increase the contact area. Will carbon paste a solution here?
Other experiences with seatpost so far:
On each slippage, the seatpost became stuck around the wheel cutout area. I had to pull the seat system with a reasonable force. I used a bar around eye-level height, cover it with some clothes, hook the saddle on to it -- after I loosen the expander, and then jerk the bike down. I hope that this force is still within the designed operating force window.
I also noticed that the seat tube doesn't have uniform thickness along its run. It became thinner a few cm in. This might be the cause of some knocking sound someone noticed before.