Single-Bolt Seatpost saddle slippage?

  • Thread starter Andrew F Martin
  • Start date



J

jim beam

Guest
Tom Kunich wrote:
> "John Forrest Tomlinson" <[email protected]> wrote in message
> news:[email protected]
>>
>> I was simply pointing out that a bolt breaking doesn't
>> necessarily result in injury -- which you said it did, at first,
>> without qualification.

>
> I'm beginning to get the idea that John is starting to use the group to
> work off his aggressions


that's not an accurate assessment of this situation. this is one of
jobst's favorite games - the switch between aggressor and victim.

rather than admit to [and correct] one of his frequent mistakes, jobst
vociferously and personally attacks instead. then, when the aggressee
defends [naturally, because defense of the mistake is unjustified],
jobst switches and plays the victim of an "unwarranted" attack!

it's grossly inappropriate and highly childish, but apparently a
successful strategy when it comes to soliciting sympathy from those who
are susceptible to suggestion.


> which obviously is one of the problems with
> groups in general. I suppose it is getting to be time to ignore his
> postings if they aren't going to add anything.
 
J

John Forrest Tomlinson

Guest
On Wed, 11 Jun 2008 07:07:24 -0700, jim beam
<[email protected]> wrote:

>Tom Kunich wrote:
>> "John Forrest Tomlinson" <[email protected]> wrote in message
>> news:[email protected]
>>>
>>> I was simply pointing out that a bolt breaking doesn't
>>> necessarily result in injury -- which you said it did, at first,
>>> without qualification.

>>
>> I'm beginning to get the idea that John is starting to use the group to
>> work off his aggressions

>
>that's not an accurate assessment of this situation. this is one of
>jobst's favorite games - the switch between aggressor and victim.


It's possibly true, but in this case I simply and politiely pointed
out an inconsistency in what Jobst wrote and he then starts
questioning "good faith" rather than simply saying "Yeah, I mispoke"
and leaving it at that.

So I get annoyed.

Tom is still an ass regardless.
 
B

Bill Sornson

Guest
Tom Kunich wrote:
> "John Forrest Tomlinson" <[email protected]> wrote in message
> news:[email protected]
>>
>> I was simply pointing out that a bolt breaking doesn't
>> necessarily result in injury -- which you said it did, at first,
>> without qualification.


> I'm beginning to get the idea that John is starting to use the group
> to work off his aggressions which obviously is one of the problems
> with groups in general. I suppose it is getting to be time to ignore
> his postings if they aren't going to add anything.


I plonked ol' Flogittodeathlinson because he's personally abusive and uses
dishonest, weasel tactics (like snipping material to hide or, much worse,
alter meaning).

However, the example you quote above doesn't seem out of line at all. He
simply stated his position (I assume addressed to Brandt, another plonkee.
How dare he challenge the almighty Jobst?).

Bill "off to the ortho (shoulder injury from tire blowout at 40 mph on a
downhill curve two weeks ago, not that anyone asked)" S.
 
J

JG

Guest
Jim, it appears you have done what you constantly accuse Jobst of
doing - talked about something you haven't actually looked at.

The Campy SR post has a semi-circular top with the bolt below on an
inner radius. If it breaks, the clamp wants to slide off. The
Suntour Superb has a cradle top. Should one bolt fail, the clamp is
still cradled on the top of the post.

JG
 
J

jim beam

Guest
JG wrote:
> Jim, it appears you have done what you constantly accuse Jobst of
> doing - talked about something you haven't actually looked at.
>
> The Campy SR post has a semi-circular top with the bolt below on an
> inner radius. If it breaks, the clamp wants to slide off. The
> Suntour Superb has a cradle top. Should one bolt fail, the clamp is
> still cradled on the top of the post.
>


i'm aware of that design. and it doesn't have the immediate "dump" fail
mode of which jobst accuses it since the post head and the bottom of the
cradle are in compression. furthermore, the design which jobst holds up
as "superior" really isn't because one bolt at either end of a two-bolt
clamp is incapable of preventing tipping, so you're pretty much in the
same position.

as for ability to follow this thread, you're still making the mistake
jobst wants you to make. jobst's response is that of the righteous
victim. in reality, /he's/ the [unjustified] aggressor - and you need
to learn that distinction. if you can't follow the technical argument,
you're in a difficult position because in most cases, it would be
correct to assume that a "victim" was the one being wronged. but in
this case, the "victim" is actually the one doing the attacking, so
you're [successfully] being suckered.
 
T

Tom Kunich

Guest
"Bill Sornson" <[email protected]> wrote in message
news:[email protected]
> Tom Kunich wrote:
>> "John Forrest Tomlinson" <[email protected]> wrote in message
>> news:[email protected]
>>>
>>> I was simply pointing out that a bolt breaking doesn't
>>> necessarily result in injury -- which you said it did, at first,
>>> without qualification.

>
>> I'm beginning to get the idea that John is starting to use the group
>> to work off his aggressions which obviously is one of the problems
>> with groups in general. I suppose it is getting to be time to ignore
>> his postings if they aren't going to add anything.

>
> I plonked ol' Flogittodeathlinson because he's personally abusive and uses
> dishonest, weasel tactics (like snipping material to hide or, much worse,
> alter meaning).


I've been bending over backwards to give him a break because he's been a
REAL(tm) bicycle racer which is rare on these groups. Originally he had a
lot of good things to add and was a nice conservative voice from the pack.
Lately however, he's gotten pretty weird.
 
B

Bill Sornson

Guest
Tom Kunich wrote:
> "Bill Sornson" <[email protected]> wrote in message
> news:[email protected]
>> Tom Kunich wrote:
>>> "John Forrest Tomlinson" <[email protected]> wrote in message
>>> news:[email protected]
>>>>
>>>> I was simply pointing out that a bolt breaking doesn't
>>>> necessarily result in injury -- which you said it did, at first,
>>>> without qualification.

>>
>>> I'm beginning to get the idea that John is starting to use the group
>>> to work off his aggressions which obviously is one of the problems
>>> with groups in general. I suppose it is getting to be time to ignore
>>> his postings if they aren't going to add anything.

>>
>> I plonked ol' Flogittodeathlinson because he's personally abusive
>> and uses dishonest, weasel tactics (like snipping material to hide
>> or, much worse, alter meaning).

>
> I've been bending over backwards to give him a break because he's
> been a REAL(tm) bicycle racer which is rare on these groups.
> Originally he had a lot of good things to add and was a nice
> conservative voice from the pack. Lately however, he's gotten pretty
> weird.


BDS. (Bush Derangement Syndrome.)

Bill "the shoulder's broken" S.
 
J

John Forrest Tomlinson

Guest
Tom Kunich wrote:
> I've been bending over backwards to give him a break because he's
> been a REAL(tm) bicycle racer which is rare on these groups.
> Originally he had a lot of good things to add and was a nice
> conservative voice from the pack. Lately however, he's gotten pretty
> weird.


No Tom, I just got fed up with your nonsense and stopped being
"polite".

Plus, as the US goes to hell it's even more disturbing to hear nuts
like you and Sorni defending evil. Voting for, say, Bush 1 or Reagan
is something we can disagree on and discuss. Supporting, say, Bush 2
for his second term, after what he's done to the constitution, the
economy and our soldiers is inexcusable and defense of it really shows
who you are. I wish I'd understood you earlier.
 
T

Tom Kunich

Guest
"John Forrest Tomlinson" <[email protected]> wrote in message
news:[email protected]
>
> No Tom, I just got fed up with your nonsense and stopped being
> "polite".


Because you've gone over the edge don't blame it on someone else.

> Plus, as the US goes to hell it's even more disturbing to hear nuts
> like you and Sorni defending evil.


I find it interesting that you seem intent on spelling Sorinson's name
incorrectly. That has a great deal to say about you.

> Supporting, say, Bush 2
> for his second term, after what he's done to the constitution, the
> economy and our soldiers is inexcusable and defense of it really shows
> who you are. I wish I'd understood you earlier.


What service were you in?
 
J

JG

Guest
>i'm aware of that design. and it doesn't have the immediate "dump" fail
>mode of which jobst accuses it since the post head and the bottom of the
>cradle are in compression.


Uh, you mean the compression from the rider sitting on it!?!? That
doesn't make it stable because actually it's under torque... and if
the rider didn't have his weight on the saddle , it wouldn't be a
problem.

Face it, neither you nor Jobst are competent to state the risk rate of
one or two bolt designs. Probably nobody is, as it would require well
controlled actuary data sets with enough incidents to be meaningful.
That leaves only anecdote and thought experiment to persuade.

But why bother? What advantage does a one bolt design have, other
than, "Look Ma! One bolt!", over its obvious drawbacks?

JG
 
J

jim beam

Guest
JG wrote:
>> i'm aware of that design. and it doesn't have the immediate "dump" fail
>> mode of which jobst accuses it since the post head and the bottom of the
>> cradle are in compression.

>
> Uh, you mean the compression from the rider sitting on it!?!? That
> doesn't make it stable because actually it's under torque...


er, that's bending, not torque. and the degree depends on rider
position. any idea how seat rail positioning evolved?


> and if
> the rider didn't have his weight on the saddle , it wouldn't be a
> problem.
>
> Face it, neither you nor Jobst are competent to state the risk rate of
> one or two bolt designs.


really? personally, i feel pretty well qualified to differentiate
between torque and bending.


> Probably nobody is, as it would require well
> controlled actuary data sets with enough incidents to be meaningful.


nobody is qualified to assess risk of one design over another? that's
like saying that the only way you can assess whether a plane is
airworthy is to crash it so you have "enough incidents to be
meaningful"!!!

reality check: every single time you sit on your bike seat and it
doesn't break, that is an "incident" with a positive outcome. the
science of metal fatigue is well advanced and allows very high
confidence for given outcomes like this - provided a designer bothers to
read any of the last century's worth of research on the subject that is.


> That leaves only anecdote and thought experiment to persuade.


what good is "thought experiment" when one doesn't even grasp enough of
the fundamentals to understand the matter at hand?


>
> But why bother? What advantage does a one bolt design have, other
> than, "Look Ma! One bolt!", over its obvious drawbacks?


even clamp loading for one.

as with many things jobstian, grabbing onto one small element of a
design, then broadcasting it as if it's the whole story, leads to gross
misunderstanding. embarrassment for the broadcaster too, if they are
capable of receiving and not just transmitting.

here's reality: double bolt designs offer no significant safety over
single bolt because once one bolt goes, the other is unbalanced and
cannot sustain anything other than a trivial load. properly executed
single bolt designs otoh are absolutely strong enough for the job.
proven non-redundant design elements are used throughout a bicycle.
there's no logical reason, particularly in view of the above, that a
seat post clamp needs, or even can successfully utilize, two bolts.
 
T

Tom Kunich

Guest
"jim beam" <[email protected]> wrote in message
news:[email protected]
> JG wrote:
>>
>> Uh, you mean the compression from the rider sitting on it!?!? That
>> doesn't make it stable because actually it's under torque...

>
> er, that's bending, not torque. and the degree depends on rider position.
> any idea how seat rail positioning evolved?


As you PEDAL you put rotational loads on the saddle back and forth. You do
understand that don't you?

>> Face it, neither you nor Jobst are competent to state the risk rate of
>> one or two bolt designs.

>
> really? personally, i feel pretty well qualified to differentiate between
> torque and bending.


And you demonstrated that exactly when?

>> Probably nobody is, as it would require well
>> controlled actuary data sets with enough incidents to be meaningful.

>
> nobody is qualified to assess risk of one design over another? that's
> like saying that the only way you can assess whether a plane is airworthy
> is to crash it so you have "enough incidents to be meaningful"!!!


I see.... You don't have a clue about aircraft design either.
 
J

jim beam

Guest
Tom Kunich wrote:
> "jim beam" <[email protected]> wrote in message
> news:[email protected]
>> JG wrote:
>>>
>>> Uh, you mean the compression from the rider sitting on it!?!? That
>>> doesn't make it stable because actually it's under torque...

>>
>> er, that's bending, not torque. and the degree depends on rider
>> position. any idea how seat rail positioning evolved?

>
> As you PEDAL you put rotational loads on the saddle back and forth. You
> do understand that don't you?
>
>>> Face it, neither you nor Jobst are competent to state the risk rate of
>>> one or two bolt designs.

>>
>> really? personally, i feel pretty well qualified to differentiate
>> between torque and bending.

>
> And you demonstrated that exactly when?
>
>>> Probably nobody is, as it would require well
>>> controlled actuary data sets with enough incidents to be meaningful.

>>
>> nobody is qualified to assess risk of one design over another? that's
>> like saying that the only way you can assess whether a plane is
>> airworthy is to crash it so you have "enough incidents to be
>> meaningful"!!!

>
> I see.... You don't have a clue about aircraft design either.


tom, this conversation lacks two elements for continuation:

1. a point - because inability to understand the difference between
torque and bending is a fundamental prerequisite.

2. the scent of sincerity - all i smell from you right now is "let's you
and me fight".

one last thing - don't snip content out of context, and /definitely/ not
without annotation. thanks so much.
 
T

Tom Kunich

Guest
"jim beam" <[email protected]> wrote in message
news:p[email protected]
> Tom Kunich wrote:
>> "jim beam" <[email protected]> wrote in message
>> news:[email protected]
>>> JG wrote:
>>>>
>>>> Uh, you mean the compression from the rider sitting on it!?!? That
>>>> doesn't make it stable because actually it's under torque...
>>>
>>> er, that's bending, not torque. and the degree depends on rider
>>> position. any idea how seat rail positioning evolved?

>>
>> As you PEDAL you put rotational loads on the saddle back and forth. You
>> do understand that don't you?
>>
>>>> Face it, neither you nor Jobst are competent to state the risk rate of
>>>> one or two bolt designs.
>>>
>>> really? personally, i feel pretty well qualified to differentiate
>>> between torque and bending.

>>
>> And you demonstrated that exactly when?
>>
>>>> Probably nobody is, as it would require well
>>>> controlled actuary data sets with enough incidents to be meaningful.
>>>
>>> nobody is qualified to assess risk of one design over another? that's
>>> like saying that the only way you can assess whether a plane is
>>> airworthy is to crash it so you have "enough incidents to be
>>> meaningful"!!!

>>
>> I see.... You don't have a clue about aircraft design either.

>
> tom, this conversation lacks two elements for continuation:
>
> 1. a point - because inability to understand the difference between torque
> and bending is a fundamental prerequisite.


Perhaps you can explain to me why you're arguing about bending when the rest
of us are discussing the fact that if the bold on a single bolt mechanism
breaks that you have ROTATIONAL forces applied to it?

> 2. the scent of sincerity - all i smell from you right now is "let's you
> and me fight".


You are the one that picks a fight with everything that Jobst writes. Often
you have to really stretch it to force his writing into some sort of form in
order to criticize it.

At times it appears that you actually have a mechanical education but then
you start trying to argue that the important forces on a single bolt
seatpost are BENDING after the bolt has been broken?

> one last thing - don't snip content out of context, and /definitely/ not
> without annotation. thanks so much.


Perhaps you'd be kind enough to take your own advice?
 
J

jim beam

Guest
Tom Kunich wrote:
> "jim beam" <[email protected]> wrote in message
> news:p[email protected]
>> Tom Kunich wrote:
>>> "jim beam" <[email protected]> wrote in message
>>> news:[email protected]
>>>> JG wrote:
>>>>>
>>>>> Uh, you mean the compression from the rider sitting on it!?!? That
>>>>> doesn't make it stable because actually it's under torque...
>>>>
>>>> er, that's bending, not torque. and the degree depends on rider
>>>> position. any idea how seat rail positioning evolved?
>>>
>>> As you PEDAL you put rotational loads on the saddle back and forth.
>>> You do understand that don't you?
>>>
>>>>> Face it, neither you nor Jobst are competent to state the risk rate of
>>>>> one or two bolt designs.
>>>>
>>>> really? personally, i feel pretty well qualified to differentiate
>>>> between torque and bending.
>>>
>>> And you demonstrated that exactly when?
>>>
>>>>> Probably nobody is, as it would require well
>>>>> controlled actuary data sets with enough incidents to be meaningful.
>>>>
>>>> nobody is qualified to assess risk of one design over another?
>>>> that's like saying that the only way you can assess whether a plane
>>>> is airworthy is to crash it so you have "enough incidents to be
>>>> meaningful"!!!
>>>
>>> I see.... You don't have a clue about aircraft design either.

>>
>> tom, this conversation lacks two elements for continuation:
>>
>> 1. a point - because inability to understand the difference between
>> torque and bending is a fundamental prerequisite.

>
> Perhaps you can explain to me why you're arguing about bending when the
> rest of us are discussing the fact that if the bold on a single bolt
> mechanism breaks that you have ROTATIONAL forces applied to it?


eh? a bolt is loaded in tension or shear. it's only subject to
rotation when it's being fastened.


>
>> 2. the scent of sincerity - all i smell from you right now is "let's
>> you and me fight".

>
> You are the one that picks a fight with everything that Jobst writes.


that's misrepresentation - i don't bother with the majority of his
emissions - only the stuff that's "tech" and blatantly wrong.


> Often you have to really stretch it to force his writing into some sort
> of form in order to criticize it.
>
> At times it appears that you actually have a mechanical education but
> then you start trying to argue that the important forces on a single
> bolt seatpost are BENDING after the bolt has been broken?


see above.


>
>> one last thing - don't snip content out of context, and /definitely/
>> not without annotation. thanks so much.

>
> Perhaps you'd be kind enough to take your own advice?
>


i haven't snipped a single letter in this thread. you otoh have snipped
whole paragraphs that in fact answered points that you have then tried
to argue against. not very honest of you.
 
T

Tom Kunich

Guest
"jim beam" <[email protected]> wrote in message
news:[email protected]
> Tom Kunich wrote:
>>
>> Perhaps you can explain to me why you're arguing about bending when the
>> rest of us are discussing the fact that if the bold on a single bolt
>> mechanism breaks that you have ROTATIONAL forces applied to it?

>
> eh? a bolt is loaded in tension or shear. it's only subject to rotation
> when it's being fastened.


Ahh, I see - you don't understand that we're talking about the SADDLE and
not the bolt. No wonder you don't have any answers that make sense.

>>> 2. the scent of sincerity - all i smell from you right now is "let's you
>>> and me fight".

>>
>> You are the one that picks a fight with everything that Jobst writes.

>
> that's misrepresentation - i don't bother with the majority of his
> emissions - only the stuff that's "tech" and blatantly wrong.


Your idea of "blatant" and the Encyclopedia Britannica are substantially
different.
 
J

jim beam

Guest
Tom Kunich wrote:
> "jim beam" <[email protected]> wrote in message
> news:[email protected]
>> Tom Kunich wrote:
>>>
>>> Perhaps you can explain to me why you're arguing about bending when
>>> the rest of us are discussing the fact that if the bold on a single
>>> bolt mechanism breaks that you have ROTATIONAL forces applied to it?

>>
>> eh? a bolt is loaded in tension or shear. it's only subject to
>> rotation when it's being fastened.

>
> Ahh, I see - you don't understand that we're talking about the SADDLE
> and not the bolt. No wonder you don't have any answers that make sense.


pleeese. the saddle rails bend. what next - discuss the torque effect
of sweat on leather. give us a break.


>
>>>> 2. the scent of sincerity - all i smell from you right now is "let's
>>>> you and me fight".
>>>
>>> You are the one that picks a fight with everything that Jobst writes.

>>
>> that's misrepresentation - i don't bother with the majority of his
>> emissions - only the stuff that's "tech" and blatantly wrong.

>
> Your idea of "blatant" and the Encyclopedia Britannica are substantially
> different.


tom, if you want to play, play it straight. thanks.
 
S

smokey

Guest
On Jun 9, 10:47 pm, Andrew F Martin <[email protected]>
wrote:
> I've got a Madone with the Bontrager single-bolt Seat Mast. 3 straight
> races I've hit a bump and had the saddle nose drop significantly.
> Anybody else have this problem with a single-bolt design?  I'm 180 and
> do tent to slide forward to the nose of the saddle (Arione) when I'm
> digging hard.
>
> My shop said to try carbon prep, and it seems a lot stickier, but
> setting up the angle was a pain.  Any alternatives?  Anybody know of
> an aftermarket Madone Seat Mast with a traditional 2-bolt design?



One thing that I've used successfully on slipping metal parts is
automotive valve lapping compound. It stopped the metal post from
slipping down in my steel framed Lemond. It might also work on your
seat post head. It can be found at any auto parts store.

Smokey
 
L

Luke

Guest
In article <[email protected]>, Tom Kunich
<[email protected]> wrote:

> "John Forrest Tomlinson" <[email protected]> wrote in message
> news:[email protected]
> >
> > No Tom, I just got fed up with your nonsense and stopped being
> > "polite".

>
> Because you've gone over the edge don't blame it on someone else.
>
> > Plus, as the US goes to hell it's even more disturbing to hear nuts
> > like you and Sorni defending evil.

>
> I find it interesting that you seem intent on spelling Sorinson's name
> incorrectly. That has a great deal to say about you.


Let's give BS his due: his name is spelled S-O-R-N-S-O-N!