slipping seatpost solutions

Raymo853 said:

The seatpost on my 2003 Gunnar Rockhound, claims to be a 27.2, always slips.
I am considering a new frame to escape this problem, painful since the frame
is fine otherwise. I bought a Syncros 27.3 seatpost to test, and it would
not fit into the frame so up-sizing is not a solution. It has done this
from day one so it was nothing I did to the frame.

The amount of slipping has varied based on the seatpost I am using. A
RockShox suspension post was the best, a Titec carbon next and the Titec AL
and current Thompson are the worse. I had hopes for the Thompson since it
has the external striations and the manufactoring tolerance they stick to,
but it has been pretty bad.

I have used both the stock collar and a salsa lip lock with no luck. I have
tightened the collars to 100% limit of my physical strength, and past the
limit of some of my allen keys with out any success. I weigh only 155 and
this happens all the time regardless of the terrain, even when riding on
smooth pavement. You can also spin the seat pretty easily.

Anyone have any ideas on stopping this? I thought about putting fine sand
into the grease or using mylar sheets as size adjusters. The only problem I
am not wild about sand in the frame and I like to move my seatpost up and
down at times for terrain changes so I am not sure the sheets will work
correctly.

Gunnars are kind of famous for this issues, both the current crop using 27.2
post and the past crop using 27.0.

Is the slot in the seat tube closing up completely? If so, can you file
it out a bit?

Raymo853' () said:

The seatpost on my 2003 Gunnar Rockhound, claims to be a 27.2, always slips.
I am considering a new frame to escape this problem, painful since the frame
is fine otherwise. I bought a Syncros 27.3 seatpost to test, and it would
not fit into the frame so up-sizing is not a solution. It has done this
from day one so it was nothing I did to the frame.

I just had a similar problem, using an different post and styled seat.

I just wrapped some duct tape around the post a couple of times. and it's
been ok so far.

steve

On Tue, 20 Apr 2004 15:39:23 -0400, "Raymo853" <[email hidden]>

may have said:

The seatpost on my 2003 Gunnar Rockhound, claims to be a 27.2, always slips.
I am considering a new frame to escape this problem, painful since the frame
is fine otherwise. I bought a Syncros 27.3 seatpost to test, and it would
not fit into the frame so up-sizing is not a solution. It has done this
from day one so it was nothing I did to the frame.

Remove the seatpost and clamp, and look at the slit in the frame tube.
There's probably a tab near the top of the slit which is keeping the
clamp from pinching the tube together properly. If that's the case,
filing the tab out will solve the problem. Also, position the clamp
so that the opening of it is lined up with the slit in the tube.

If there isn't a slit, or if the slit is less than 15mm in length, you
may need to make one. I've found that 25mm of slit is almost always
adequate even with thick aluminum tubing, and a shorter slit may still
work with thinwall Cr-Mo tubing. Try to avoid leaving sharp edges or
corners, and your setpost won't get scarred as badly.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

Raymo853 said:

The seatpost on my 2003 Gunnar Rockhound, claims to be a 27.2, always slips.
I am considering a new frame to escape this problem, painful since the frame
is fine otherwise. I bought a Syncros 27.3 seatpost to test, and it would
not fit into the frame so up-sizing is not a solution. It has done this
from day one so it was nothing I did to the frame. ...

Quoted message said:

Anyone have any ideas on stopping this? I thought about putting fine sand
into the grease or using mylar sheets as size adjusters. The only problem I
am not wild about sand in the frame and I like to move my seatpost up and
down at times for terrain changes so I am not sure the sheets will work
correctly.

I have used shims cut from aluminum pop/beer cans to stop
slipping seatposts. It does work. If the fit is close the shim
will not have to go all the way around. It may be a nuisance
to keep the shim in place if you adjust seat height a lot.

Other more professional options are to get a seatpost knurled or
to get a shop or framebuilder to ream or hone the seat tube to a
known size, like 27.4, and use a stock 27.4 seatpost. Are you sure
the Syncros post wasn't 27.4mm? I never heard of a 27.3 mm post.
Aluminum seatposts can also be sanded down slightly to improve a
just barely too-tight fit. Anyway it should be fixable without
needing a new frame.

"Raymo853" asked about the slipping seatpost:

<< Anyone have any ideas on stopping this? >>

Fold up a little bit of that very lightweight foil-like candy wrapper and cram
it between the post and the inside of the frame as you lower the post into the
seat tube. That will stop it.

Robert

Quoted message said:

Quoted message said:

The seatpost on my 2003 Gunnar Rockhound, claims to be a 27.2, always

slips.

Quoted message said:

I am considering a new frame to escape this problem, painful since the

frame

Quoted message said:

is fine otherwise. I bought a Syncros 27.3 seatpost to test, and it would
not fit into the frame so up-sizing is not a solution. It has done this
from day one so it was nothing I did to the frame.

Have a shop run a 27.2 reamer through it. You may just be clamping the post in
a couple of places.
Phil Brown

Quoted message said:

The seatpost on my 2003 Gunnar Rockhound, claims to be a 27.2,
always slips. I am considering a new frame to escape this problem,
painful since the frame is fine otherwise. I bought a Syncros
27.3 seatpost to test, and it would not fit into the frame
so up-sizing is not a solution.

I had a similar problem with my old Montague. Turned out the
factory-provided seatpost *was* too small, which I deduced after
carefully measuring the seat tube outside diameter and wall thickness at
several points. Fitting a 0.4mm-larger seatpost was the cure, but
involved a good bit of work, because several months of tightening and
re-tightening the clamp had deformed the top of the seat tube, and the
larger-diameter seatpost wouldn't go in. I restored the sizing and
roundness of the seat tube by forcefully rotating a short length of
water-pipe inside it, using an automotive half-inch-drive "breaker bar"
as a lever: the handle end of the breaker-bar went inside the pipe,
which went inside the seat tube, with a small [maybe 2mm] clearance
between each, enough for me to rotate 'round while wrestling with the
frame to keep it still. Crude, but effective: the new, larger seatpost
glides up & down just as intended.

"Phil Brown" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Have a shop run a 27.2 reamer through it. You may just be clamping the

post in

Quoted message said:

a couple of places.
Phil Brown

Won't that make it bigger and slip even more? Actually I am assuming a 27.2
reamer would end up not even touching the interior of the seat tube.

"You may just be clamping the post in a couple of places." What does that
mean?

"Benjamin Weiner" <[email hidden]> wrote in message
news:4085a2eb$1@darkstar...

Quoted message said:

Other more professional options are to get a seatpost knurled or
to get a shop or framebuilder to ream or hone the seat tube to a
known size, like 27.4, and use a stock 27.4 seatpost. Are you sure
the Syncros post wasn't 27.4mm? I never heard of a 27.3 mm post.
Aluminum seatposts can also be sanded down slightly to improve a
just barely too-tight fit. Anyway it should be fixable without
needing a new frame.

I am 100% sure it was a 27.3. It was made for those few Waterfords that
used 27.3 seatposts.

I am not going to do the reaming. I do not like this frame enough to put
money into having it reamed, I would rather go get a quality frame like an
IF instead.

rcc-<< The seatpost on my 2003 Gunnar Rockhound, claims to be a 27.2, always
slips.
I am considering a new frame to escape this problem, painful since the frame
is fine otherwise. >><BR><BR>

Have a competent LBS 'knurl' the seatpost where it goes into the frameset or
have same competent LBS slightly rear the seatube to accomodate a larger
seatpost...no need to get rid of the frameset.

rcc-<< Gunnars are kind of famous for this issues, both the current crop using
27.2
post and the past crop using 27.0. >><BR><BR>

Waterford products have been kind of 'famous' for this for years.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

Quoted message said:

"Benjamin Weiner" <[email hidden]> wrote in message
news:4085a2eb$1@darkstar...

Quoted message said:

Other more professional options are to get a seatpost knurled or
to get a shop or framebuilder to ream or hone the seat tube to a
known size, like 27.4, and use a stock 27.4 seatpost. Are you sure
the Syncros post wasn't 27.4mm? I never heard of a 27.3 mm post.
Aluminum seatposts can also be sanded down slightly to improve a
just barely too-tight fit. Anyway it should be fixable without
needing a new frame.

Raymo853 said:

I am 100% sure it was a 27.3. It was made for those few Waterfords that
used 27.3 seatposts.

I am not going to do the reaming. I do not like this frame enough to put
money into having it reamed, I would rather go get a quality frame like an
IF instead.

That cost is minimal. Also, seatposts vary quite a bit
(which you can see at any bike shop if you bring a micrometer).

It may indeed be not round but more likely an undersized or
mismarked post. A post may be knurled, BTW, saving even the
cost of a post, so yet another reason to consult a good
frame service shop.

And Waterford ran 27.4, as did a few top-end Italian bikes,
but not 27.3.

Why the gratuitous slam? Both IF and Waterford are at the
pinnacle of our industry.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971