Strange Failure (Trans X shock absorbing seat post), How to repair?

A first I've heard of, my seat post failed, the only expensive component
on the bike. It broke cleanly at the top of the frame, at the front,
and the seat post swung backwards to the milk crate mounted behind
it

http://home.att.net/~rhhardinc/failure002.jpg

You face a decision : do you pedal onwards to your destination, exposing
yourself to a risk of an additional 5 miles if it truly breaks down,
or return home from the point you're at. I proceeded onwards

http://home.att.net/~rhhardinc/failure001.jpg

with the seat tied to the handle bar stem with a handy section of
nylon dog leash that seemed like a good idea to pack once.

I made it home (I now have a theory of stand-up ergonomics) by not
using the seat, and remembering that I have to mount and dismount
in the traditional guy fashion rather than swinging a foot over
the top bar as I preferred.

Swinging the seat back and forth a dozen times broke the remaining
bit of seat post at the rear, and now there is the problem of
getting the aluminum seat post remnant out of the steel bike frame.

It's welded itself in place.

There's a bottom to the aluminum tube remnant, so I put a huge drift
punch in against it, got a heavy sledge hammer, and gave it many good
whacks, to no effect, trying to break it free. No luck, and I finally
broke through the bottom, ending that direction of repair.

So this aluminum tube sits welded to this steel frame. Any ideas
how to separate them? I have several good places to grip the
tube, but it really thinks it's structurally part of the steel, I think.

Ironic that the bike finally gets finished off by the most expensive
component.

Don't buy these

http://home.att.net/~rhhardinc/failure003.jpg


--
Ron Hardin


On the internet, nobody knows you're a jerk.

On 2007-07-16, Ron Hardin wrote:
A first I've heard of, my seat post failed, the only expensive component
on the bike. It broke cleanly at the top of the frame, at the front,
and the seat post swung backwards to the milk crate mounted behind
it

This sort of brake is common when the seatpost is raised above its
minimum insertion line. I can't see the line in the photo so this may
not be the problem, but you should check this when you get a new
seatpost.

As for getting the old post out, soak in WD40/RP7/whatever overnight and
try gripping the post at the slot in the seat tube with needle nosed
vise grips. If that fails slot the seat tube down its remaining length
and roll it up into itself. It should come out fairly easily.

If you put a layer of grease down the seat tube when you install the new
seatpost it shouldn't rust in again

Cheers

Joel


--
Human Powered Cycles | High quality servicing and repairs
| Affordable second hand bikes
(03) 9029 6504 | Bicycle reuse centre
www.humanpowered.com.au | Mechanical and on-road training and instruction

In article ,
Ron Hardin wrote:

A first I've heard of, my seat post failed, the only expensive component
on the bike. It broke cleanly at the top of the frame, at the front,
and the seat post swung backwards to the milk crate mounted behind
it

http://home.att.net/~rhhardinc/failure002.jpg

You face a decision : do you pedal onwards to your destination, exposing
yourself to a risk of an additional 5 miles if it truly breaks down,
or return home from the point you're at. I proceeded onwards

http://home.att.net/~rhhardinc/failure001.jpg

with the seat tied to the handle bar stem with a handy section of
nylon dog leash that seemed like a good idea to pack once.

I made it home (I now have a theory of stand-up ergonomics) by not
using the seat, and remembering that I have to mount and dismount
in the traditional guy fashion rather than swinging a foot over
the top bar as I preferred.

Swinging the seat back and forth a dozen times broke the remaining
bit of seat post at the rear, and now there is the problem of
getting the aluminum seat post remnant out of the steel bike frame.

It's welded itself in place.

There's a bottom to the aluminum tube remnant, so I put a huge drift
punch in against it, got a heavy sledge hammer, and gave it many good
whacks, to no effect, trying to break it free. No luck, and I finally
broke through the bottom, ending that direction of repair.

So this aluminum tube sits welded to this steel frame. Any ideas
how to separate them? I have several good places to grip the
tube, but it really thinks it's structurally part of the steel, I think.

From your description it is likely the Al oxidized and
the compound expanded. Best bet is to cut away the Al
from the inside out. First choice is a horizontal mill.
Next is a drill press. Rotate the bed of the drill
press out of the way. Then find a way to securely clamp
the seat tube dead vertical. Perhaps you can use the
edge of the drill press bed. The remainder of the job
is a doddle.

--
Michael Press

Ron Hardin wrote:
A first I've heard of, my seat post failed, the only expensive component
on the bike. It broke cleanly at the top of the frame, at the front,
and the seat post swung backwards to the milk crate mounted behind
it
http://home.att.net/~rhhardinc/failure002.jpg
You face a decision : do you pedal onwards to your destination, exposing
yourself to a risk of an additional 5 miles if it truly breaks down,
or return home from the point you're at. I proceeded onwards
http://home.att.net/~rhhardinc/failure001.jpg
with the seat tied to the handle bar stem with a handy section of
nylon dog leash that seemed like a good idea to pack once.
I made it home (I now have a theory of stand-up ergonomics) by not
using the seat, and remembering that I have to mount and dismount
in the traditional guy fashion rather than swinging a foot over
the top bar as I preferred.
Swinging the seat back and forth a dozen times broke the remaining
bit of seat post at the rear, and now there is the problem of
getting the aluminum seat post remnant out of the steel bike frame.
It's welded itself in place.
There's a bottom to the aluminum tube remnant, so I put a huge drift
punch in against it, got a heavy sledge hammer, and gave it many good
whacks, to no effect, trying to break it free. No luck, and I finally
broke through the bottom, ending that direction of repair.
So this aluminum tube sits welded to this steel frame. Any ideas
how to separate them? I have several good places to grip the
tube, but it really thinks it's structurally part of the steel, I think.
Ironic that the bike finally gets finished off by the most expensive
component.
Don't buy these
http://home.att.net/~rhhardinc/failure003.jpg

With all respect I don't believe Trans-X are any different from any
other aluminum post. Having just spent over an hour removing the
remnants of a broken post stump I think you're in for a real adventure now.

Your bike doesn't look all that rusty. But since you report that it is
indeed stuck, know that oxides are larger and less dense than metals.
Corrosion between a snug-fitting aluminum post in a steel tube is really
tight once any moisture gets in. And it always gets in.

If it is mildly corroded you may be able to slit one side, curl up the
edge and withdraw the post. That can be tedious. Here's an example:
http://www.yellowjersey.org/goodn.html

If it is severely corroded you may be able to slowly ream the post in
multiple passes until there is only a shell of corroded hard oxide left.
Polish that away with a tube polisher or hone. With good
tooling,(letter H reamer, solid long Starrett handle, rigid work stand)
expect about an hour and a half of vigorous work.

If your time has any value, melt out the post. Remove any equipment you
don't want to immolate (cables, etc) . Position the seat tube nearly
horizontal over a bucket of water. A welding rod or similar helps to
pull out the melted aluminum once it's plastic. It won't flow well if
there's a lot of oxide. The aluminum melts at a temperature well below
any damage to the steel.

Acid etch, primer and color complete your adventure. Once or twice
annually, a seatpost clean/lube in future!
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

In article ,
Ron Hardin wrote:

A first I've heard of, my seat post failed, the only expensive component
on the bike. It broke cleanly at the top of the frame, at the front,
and the seat post swung backwards to the milk crate mounted behind
it

http://home.att.net/~rhhardinc/failure002.jpg

You face a decision : do you pedal onwards to your destination, exposing
yourself to a risk of an additional 5 miles if it truly breaks down,
or return home from the point you're at. I proceeded onwards

http://home.att.net/~rhhardinc/failure001.jpg

with the seat tied to the handle bar stem with a handy section of
nylon dog leash that seemed like a good idea to pack once.

I made it home (I now have a theory of stand-up ergonomics) by not
using the seat, and remembering that I have to mount and dismount
in the traditional guy fashion rather than swinging a foot over
the top bar as I preferred.

Swinging the seat back and forth a dozen times broke the remaining
bit of seat post at the rear, and now there is the problem of
getting the aluminum seat post remnant out of the steel bike frame.

It's welded itself in place.

There's a bottom to the aluminum tube remnant, so I put a huge drift
punch in against it, got a heavy sledge hammer, and gave it many good
whacks, to no effect, trying to break it free. No luck, and I finally
broke through the bottom, ending that direction of repair.

So this aluminum tube sits welded to this steel frame. Any ideas
how to separate them? I have several good places to grip the
tube, but it really thinks it's structurally part of the steel, I think.

Michael Press wrote:
From your description it is likely the Al oxidized and
the compound expanded. Best bet is to cut away the Al
from the inside out. First choice is a horizontal mill.
Next is a drill press. Rotate the bed of the drill
press out of the way. Then find a way to securely clamp
the seat tube dead vertical. Perhaps you can use the
edge of the drill press bed. The remainder of the job
is a doddle.

Clamping the frame rigidly and in line with a reamer isn't trivial.

When I worked for Ray Gasiorowski, I sent a 27.2 reamer right out the
side of a new freshly painted custom frame's seat tube. Ouch.

To his credit, he didn't murder me on the spot, as I richly deserved.

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

Ron Hardin wrote:
...
So this aluminum tube sits welded to this steel frame. Any ideas
how to separate them? I have several good places to grip the
tube, but it really thinks it's structurally part of the steel, I think....

What would Sheldon do [1]?

See http://sheldonbrown.com/stuck-seatposts.html.

[1] Insert snarky retort from Ozark Bicycle here for mentioning S. Brown.

--
Tom Sherman - Holstein-Friesland Bovinia
The weather is here, wish you were beautiful

--
Posted via a free Usenet account from http://www.teranews.com

Joel Mayes wrote:
This sort of brake is common when the seatpost is raised above its
minimum insertion line. I can't see the line in the photo so this may
not be the problem, but you should check this when you get a new
seatpost.

There was lots of length below the seat tube, so it's not that. Indeed
the length there is more of a problem, more material to weld itself in.

I'm surprised at the failure, because there's certainly no particular
load on the seat tube. I only weigh 150, and use the bike for
commuting and errands, not rock jumping. I have maybe 20k miles on
this particular bike.

Maybe I'll stick with steel seat posts in the future, if the aluminum
ones all tend to do this.
--
Ron Hardin


On the internet, nobody knows you're a jerk.

On Tue, 17 Jul 2007 08:52:07 GMT, Ron Hardin
wrote:

Maybe I'll stick with steel seat posts in the future, if the aluminum
ones all tend to do this.

You think they all tend to break this way? If so, why do you call the
failure strange?
--
JT
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John Forrest Tomlinson wrote:

On Tue, 17 Jul 2007 08:52:07 GMT, Ron Hardin
wrote:

Maybe I'll stick with steel seat posts in the future, if the aluminum
ones all tend to do this.

You think they all tend to break this way? If so, why do you call the
failure strange?

I thought it was unique. It was, in my experience. But people responded
that it's a fairly common problem, which I put down to my inexperience
with expensive bike parts. I had always gone with steel before.

Oh except I had a Campy seat post on my long-ago stolen Raleigh
International, that didn't break. Now there was a nice bike.

--
Ron Hardin


On the internet, nobody knows you're a jerk.

On 2007-07-17, Ron Hardin wrote:
John Forrest Tomlinson wrote:

On Tue, 17 Jul 2007 08:52:07 GMT, Ron Hardin
wrote:

Maybe I'll stick with steel seat posts in the future, if the aluminum
ones all tend to do this.

You think they all tend to break this way? If so, why do you call the
failure strange?

I thought it was unique. It was, in my experience. But people responded
that it's a fairly common problem, which I put down to my inexperience
with expensive bike parts. I had always gone with steel before.

It's common the when a seat post brakes it brakes there. It's not comon
for seat posts to brake.

--
Human Powered Cycles | High quality servicing and repairs
| Affordable second hand bikes
(03) 9029 6504 | Bicycle reuse centre
www.humanpowered.com.au | Mechanical and on-road training and instruction