Creeping seatpost

On Mar 3, 9:44*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?


Why not replace the clamp with a metal one?

Also, measuring the post and tube are good ideas...

nate

On Mar 3, 9:27*pm, Jobst Brandt wrote:

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

That's funny. I worked in the trade for ten years, five as a licensed
journeyman plumber, and that's the first time I ever heard hanging
strap called "tape".

Not being a know-it-all, I googled, and sure enough, perf hanging
strap ("iron") is the second choice of meanings for "plumber's tape".

I think this expression went out of style, probably around 1897 or so,
because it is so completely inapt when applied to strap iron.

Tef tape, OTOH, is tape and it is primarily "plumber's", AFAIK, mostly
used (when used as intended) in tapered-thread connections, where it
is frequently a "life saver" when used with the usual poorly made crap
one encounters when trying to get the water/wastewater to stay inside
the pipes and fittings and valves where it belongs.

Moreover, I was glad to learn there is a third entry in the "plumber's
tape" google list-- a vinyl tape meant to cover and protect pipe and
fittings.
Never saw that in my new work, repair/remodel, or v. limited
commercial construction experience.

Whatever. "plumber's tape" = teflon tape, by actual common usage.
--D-y, Texas State Board of Plumbing Examiners, Inactive Journeyman
Lic. #J-27xxx

On Mar 4, 1:34*am, "Mike Jacoubowsky" wrote:
"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 Bicycleswww.ChainReaction.com
Redwood City & Los Altos, CA USA

I agree with Mike; a bike shop is the first choice to solve this
problem.

However, from pictures of your bike on the net, it appears this bike
has a quick release seat post clamp. Your first step (besides going
to a LBS) would be to lubricate the cam portion. And don't be afraid
to get it tight -- I assure you it's not made of Nylon...

N8N wrote:


On Mar 3, 9:44*pm, "Jack Myers" wrote:
Over the course of an hour' ride my seatpost will get pounded into
the frame.

Also, measuring the post and tube are good ideas...

Thanks all for the really helpful suggestions. My strategy will be to
mike the seatpost to make sure it is not tapered. Lube the clamp bolt
and overtorque it, secure in the knowledge that better aftermarket
replacements are readily available if I break the original. There's
teflon tape, and even valve grinding compound, in the garage.

Already tried the blinkey clamp idea with no joy.

Mike, I don't hold the LBS responsible because it's been a few years,
I've moved, and I should have gotten in front of this problem sooner.


--
Jack Myers / Westminster, California, USA

"Words ought to be a little wild for they are the assaults of thought on the unthinking." - John Maynard Keynes

On 4 Mar, 14:26, N8N wrote:
Also, measuring the post and tube are good ideas...

Don't let it fool you, since it might.
The tube may be too large down below, although it appears to fit
nicely at the collar,
being deformed up there.

Sergio
Pisa

On Mar 3, 7:44 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



If you find that your problem is not easily solved by clamping harder
or getting the right size seatpost, try this:

Fold up a Twix wrapper (make sure it's a Twix) into a point so that
you can jam it between the post and the frame as you push the post
into the seat tube. Install to correct height. Trim excess. That'll do
'er.

On 4 Mar, 18:31, RobertH wrote:
Fold up a Twix wrapper (make sure it's a Twix) into a point so that
you can jam it between the post and the frame as you push the post
into the seat tube. Install to correct height. Trim excess. That'll do
'er.

A mylar foil does it too.

Sergio
Pisa

On Mar 4, 12:31*pm, RobertH wrote:
On Mar 3, 7:44 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

If you find that your problem is not easily solved by clamping harder
or getting the right size seatpost, try this:

Fold up a Twix wrapper (make sure it's a Twix) into a point so that
you can jam it between the post and the frame as you push the post
into the seat tube. Install to correct height. Trim excess. That'll do
'er.

If it just needs a thin shim, I'd think that metal duct tape might
work.

nate

On Mar 3, 11:34*pm, "Mike Jacoubowsky"
wrote:
"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?

I would take it to a shop to check the size. They should have a
seatpost sizing rod similar to the following that can determine the
correct diameter:

http://www.biketoolsetc.com/index.cg...&item_id=SN-SR

I agree that it could also be the clamp. In which case, they should be
able to determine if its not holding properly. Good Luck!

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?

Ben C writes:
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.

Simon Lewis wrote:
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.


You may be mistaken on that.
Thread friction and galling under the head of a steel bolt
in aluminum can be significant.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971