"David Kunz" <
[email protected]> wrote in message
news:[email protected]...
> frank121 wrote:
> > I was doing some routine maintenance today on the bike. When I was
taking
> > the seatpost out and re-greasing it, I felt a mild indention on either
side
> > of the post. Looks like this is where the seatpost has been clamped in
the
> > seattube on either side of the seatpost. No break, but enough of a difference I could feel the
> > difference when I ran my finger down the
sides.
> >
> > Anything to worry about? Time to replace the seatpost?
> >
> > Thanks,
> >
> > Frank
> >
>
> It could be that your seat clamp is mismatched to your bike. The clamp has a ring/ridge around the
> top to keep it from sliding down the seatpost tube. If this ring is coming into contact with the
> seatpost, it'll crimp it like you describe because it won't tighten properly over the whole
> friction area -- just at the ring. Tompson MAY replace it if this has happened. My Tompson cracked
> in one of the thin areas and collapsed slightly when I tightened it to make up for the fact that
> it was now not holding. They replaced it, but sent me a tech note explaining the above and saying
> that they would not consider that kind of damage a warranty return. I believe that it's also
> mentioned in the installation instructions (that EVERYONE reads
).
>
Yeah, but did Thomson also mention that they design and manufacture their seatposts such that, if
anything, the seatpost will be smaller than the nominal diameter. This means that in some frames,
the post may be a sloppy fit and when you clamp down on it to keep it from slipping, you can end up
with the indentations described above. I had a 27.2mm Thomson post that I couldn't keep from
slipping in two different frames no matter what I did. I had used three or four other 27.2 posts in
these frame with no slippage (bending was the issue with them). The Thomson post was the loosest fit
of the lot so I contacted Thomson. They told me their design and manufacturing tolerances and when I
measured my seatpost with a micrometer, it's diameter was right at the small end of the tolerance
stack-up. To their credit, Thomson sent me another post that was closer to nominal diameter and that
fixed the issue