Bill Sornson wrote:
Jobst Brandt wrote:
Bill Sornson wrote:

Over the course of an hour' ride my seatpost will get pounded into
the frame. This is a stock Trek 7200 hybrid and I'm reluctant to
tighten the [nylon?] clamp any more. (Yes, I'm a large rider.)

The problem will only get worse over time. I'm considering green
Loctite. Will that work? Anyone have a better suggestion?

Lots of things you can do. Assuming the post is correct (accurate)
size, you can try a little plumber's tape or other "shim type" fix;
or use a clamp of sorts above the insertion point to help keep the
post from sliding down. (Plastic blinky holder or a full on hose
clamp, for examples.)

The OE clamp shouldn't be nylon, I wouldn't think. Mine are all
metal and I tend to over-tighten stuff; haven't had a problem yet.

Loctite might work, but I'd worry about it causing a "frozen" post.
Others may have experience with it though...

If it's really sliding all the way into the frame on rides, then I'd
say your post is undersized. Visit a bike shop to measure, maybe?

Well, plumbers tape (ain't tape) is thick steel.

Geez, Jobst, for a humorless pedant you sure are funny sometimes.

A) It's plumber's tape with an apostrophe. B) The common variety
sold in Home Despot and every other hardware store is thin, teflon
wrapping, not "thick steel" /strapping/.

Very first Google hit: http://www.wisegeek.com/what-is-plumbers-tape.htm
I'd try a section
out of a soda-pop can or beer can. They are easily cut with
household scissors into a one inch wide band, and see if that can be
made to fit. One full wrap or even more should do the job if it
really is an undersized post that it seems to be. Use grease for
final tightening to prevent future water intrusion.

Jobst Brandt

Since it's sliding down so dramatically, you might be right about the
fix. You might have replied to the OP with that, and skipped the
needless (and wrong) nitpick about plumber's tape.

HTH! (But not betting on it.)

BS

PS: You also deleted the OP's attribution. Yet another Usenet /faux
pas/...