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Creeping seatpost



 
 
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  #1  
Old March 4th 10, 03:44 AM posted to rec.bicycles.tech
Jack Myers
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Posts: 2
Default Creeping seatpost

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
Loktite. Will that work? Anyone have a better suggestion?


--
Jack Myers / Westminster, California, USA

Our policy is, when in doubt, do the right thing.
-- Roy L. Ash, ex-president, Litton Industries


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  #2  
Old March 4th 10, 04:12 AM posted to rec.bicycles.tech
Bill Sornson[_5_]
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Posts: 1,541
Default Creeping seatpost

Jack Myers 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
Loktite. 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.

Loktite 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?

Good luck. Bill S.


  #3  
Old March 4th 10, 04:26 AM posted to rec.bicycles.tech
landotter
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Posts: 6,336
Default Creeping seatpost

On Mar 3, 8:44*pm, "Jack Myers" 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
Loktite. Will that work? Anyone have a better suggestion?


Clamp it harder--it's aluminum and steel with possibly a nylon cam. If
it still slips, get a proper hex-key collar (you can sometimes convert
a QR model to keyed), grease the threads and tighten with a torque
wrench to the specifications. The Salsa Lip-Lock is a nice strong
model and pretty commonly available at bike shops.
  #4  
Old March 4th 10, 04:37 AM posted to rec.bicycles.tech
Bill Sornson[_5_]
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Posts: 1,541
Default Creeping seatpost

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


  #5  
Old March 4th 10, 05:12 AM posted to rec.bicycles.tech
Bill Sornson[_5_]
external usenet poster
 
Posts: 1,541
Default Creeping seatpost

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/...


  #6  
Old March 4th 10, 05:13 AM posted to rec.bicycles.tech
Sergio Moretti
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Posts: 105
Default Creeping seatpost

On Mar 3, 8:44*pm, "Jack Myers" 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
Loktite. Will that work? Anyone have a better suggestion?

--
Jack Myers / Westminster, California, USA

Our policy is, when in doubt, do the right thing.
* * * * * * * * -- Roy L. Ash, ex-president, Litton Industries


The clamp is probably aluminum -- make sure the screw threads are duly
lubricated.
You could also try friction paste between seat post & frame. Tacx &
Ritchey sell it, to name two.
  #7  
Old March 4th 10, 07:02 AM posted to rec.bicycles.tech
Hugh Fenton[_2_]
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Posts: 19
Default Creeping seatpost


"Sergio Moretti" wrote in message
...
On Mar 3, 8:44 pm, "Jack Myers" 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
Loktite. Will that work? Anyone have a better suggestion?

--
Jack Myers / Westminster, California, USA

Our policy is, when in doubt, do the right thing.
-- Roy L. Ash, ex-president, Litton Industries


The clamp is probably aluminum -- make sure the screw threads are duly
lubricated.
You could also try friction paste between seat post & frame. Tacx &
Ritchey sell it, to name two.


If you (or your dad/granddad) is old school, he's sure to have a small
container of valve grinding paste hanging around somewhere. Its just the
right grit size to stop movement, all embedded in a lubricant. Been using it
for years in an old aluminium CADEX where I'm always adjusting the seat
height - and can't be bothered with a too tight clamp.
Hugh Fenton


  #8  
Old March 4th 10, 08:34 AM posted to rec.bicycles.tech
Mike Jacoubowsky
external usenet poster
 
Posts: 2,972
Default Creeping seatpost

"Jack Myers" wrote in message
...
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
Loktite. Will that work? Anyone have a better suggestion?


--
Jack Myers / Westminster, California, USA

Our policy is, when in doubt, do the right thing.
-- Roy L. Ash, ex-president, Litton Industries


Have you brought it back to the shop it came from? It could be a
slightly-undersized seatpost, or a clamp that's not exerting enough force.
Whatever the case, any decent shop should take such an issue seriously on a
bike they sold, and help work out a solution. Or have you already done that
without success?

If the post *is* undersized, and it's the one that came with the bike, it
makes a lot more sense to get a post that works for it instead of a kludge
fix found on the 'net. If it's a used bike that's been through the war, then
all bets are off and maybe the frame is distorted enough in the seatpost
area that a kludge is the best you can do.

--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
Redwood City & Los Altos, CA USA

  #9  
Old March 4th 10, 09:41 AM posted to rec.bicycles.tech
Ben C
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Posts: 3,084
Default Creeping seatpost

On 2010-03-04, Jack Myers 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
Loktite. Will that work? Anyone have a better suggestion?


Get a better clamp. They're replaceable and just sit on the top of the
seat-tube.

This is the best one I've used:

http://www.identitibikes.com/identit...php?id=SCIDB28

Put a bit of grease on the bolt on the clamp so you're sure to be
tightening it up properly.
  #10  
Old March 4th 10, 10:36 AM posted to rec.bicycles.tech
Simon Lewis
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Posts: 441
Default Creeping seatpost

Ben C writes:

On 2010-03-04, Jack Myers 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
Loktite. Will that work? Anyone have a better suggestion?


Get a better clamp. They're replaceable and just sit on the top of the
seat-tube.

This is the best one I've used:

http://www.identitibikes.com/identit...php?id=SCIDB28

Put a bit of grease on the bolt on the clamp so you're sure to be
tightening it up properly.


Adding grease would make zero difference to the tightening. The
considerable force applied for the final tight turns would really not be
affected at that point by any grease.

 




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