Originally Posted by
Kommisar89
Now there we disagree - maybe the clamp on top of it is an external part but the post itself is there to allow you to fine tune the length of the seat tube which is part of the frame.
But think about what you are implying there - hypothetically if we could build a frame of some new design with some unobtanium new material such that it had absolutely zero flex but the seat post still flexed a great deal, you would ride that bike and still think it was flexy. You cannot separate the seat post from the frame outside of a laboratory.
I doubt you could really get a seatpost long enough to get it to flex that much, since they are made of such thick-walled aluminum. My 15" compact geo mtb frame has about 3" more seatpost showing than a 17" mtb, it actually feels stiffer in the pedals.
The flex that is undesirable in bike frames is generally not related to flex in the seatpost.
I take it you're not in the market for a Trimble.