gregoryoftours wrote:It's actually less that they're designed to be fitted with a bit of post up, but that installing them down to the top cap/collar can result in the action binding. This is especially true if the tolerances are a bit sloppy between the frame and the post so the seat clamp is done up tight to compensate. It's best to use carbon assembly paste with a dropper post so that less clamping force is needed, and clamp a couple of inches below the top cap.
That still doesn't ring any bells with me. I've never heard any manufacturer advise against installing a dropper post all the way into the frame until the top cap is touching. I've just searched the online manuals and can confirm that KS Lev, PNW and OneUp don't mention it and I installed both my X-fusion and Tranz X posts, so I know they don't advise against it. They all mention the golden rule which applies to all seat posts - i.e. make sure it goes to the minimum insertion depth, or you risk breaking your frame. If you've got any references to where the 'don't fully insert' advice comes from, I'd be keen to see as my Tranz X is indeed installed all the way into my XC bike's frame but, touch wood, has worked flawlessly.
Obviously, over-tightening the seat clamp isn't a good idea, but over-tightening anything never is - so assembly paste is usually a better bet than grease to prevent the post corroding in.