Originally Posted by DannoXYZ

Well considering that weight and road-bumps load the seatpost vertically along its axis, I doubt a CF post would compress any more than an alloy post (which is basically nil). The flex you're experiencing and that your teammates are seeing is lateral flex due to your weight and leg muscles pushing on the post. A seatpost is much, much more flexible laterally across its axis than along it, so a lightweight CF would probably flex more for the same lateral load.

Yea, I'd say go with a more stout alloy post. You'd never feel the 50-100gm weight difference, but you can definitely feel the difference in lateral rigidity.