Single-Bolt Seatpost saddle slippage?

jim beam

JG wrote:
> I had a one bolt Campy for a long time. I would tighten it very hard
> and it would still eventually slip. The original Avocet design was
> perfect, and I was lucky to find a Suntour Superb in 27.0. I'd love a
> Nitto Jaguar, but I'd have to be drunk to PayPal that kind of money.
> I've never understood why two bolts is not universal. You keep the
> angle and move the seat backward and forward by loosening and
> retightening only one bolt, or keep the displacement the same and only
> change the angle by loosening one bolt as you tighten the other.
> Brilliant!

not really. if one bolt breaks, the remainder of the cradle is
unbalanced and fails under trivial load. pointless really, especially
for a system where tilt load is the main fatigue factor. much better to
have a single bolt at what would effectively be the "neutral plane".

* * Chas

"JG" <jchg@cox.net> wrote in message
news:55a3f601-2730-4ea3-98e8-818ce6bcd053@z16g2000prn.googlegroups.com...
> I had a one bolt Campy for a long time. I would tighten it very hard
> and it would still eventually slip. The original Avocet design was
> perfect, and I was lucky to find a Suntour Superb in 27.0. I'd love a
> Nitto Jaguar, but I'd have to be drunk to PayPal that kind of money.
> I've never understood why two bolts is not universal. You keep the
> angle and move the seat backward and forward by loosening and
> retightening only one bolt, or keep the displacement the same and only
> change the angle by loosening one bolt as you tighten the other.
> Brilliant!
>
> JG

Back in the day there were a lot of complaints about mounting seats and
adjusting them with Campy 2 bolt style seatposts (and similar knockoffs).
It was partly due to not having a proper fitting 10mm wrench to get to the
bolt heads. The Avocet and similar 2 bolt seatposts that used socket head
cap screws accessible from the bottom was a great solution.

I've switched most of my bikes back to 2 bolt Campy seatposts.

Chas.

jim beam

* * Chas wrote:
> "JG" <jchg@cox.net> wrote in message
> news:55a3f601-2730-4ea3-98e8-818ce6bcd053@z16g2000prn.googlegroups.com...
>> I had a one bolt Campy for a long time. I would tighten it very hard
>> and it would still eventually slip. The original Avocet design was
>> perfect, and I was lucky to find a Suntour Superb in 27.0. I'd love a
>> Nitto Jaguar, but I'd have to be drunk to PayPal that kind of money.
>> I've never understood why two bolts is not universal. You keep the
>> angle and move the seat backward and forward by loosening and
>> retightening only one bolt, or keep the displacement the same and only
>> change the angle by loosening one bolt as you tighten the other.
>> Brilliant!
>>
>> JG
>
> Back in the day there were a lot of complaints about mounting seats and
> adjusting them with Campy 2 bolt style seatposts (and similar knockoffs).
> It was partly due to not having a proper fitting 10mm wrench to get to the
> bolt heads. The Avocet and similar 2 bolt seatposts that used socket head
> cap screws accessible from the bottom was a great solution.
>
> I've switched most of my bikes back to 2 bolt Campy seatposts.
>

let's say the front bolt breaks for some reason. how would the rear
bolt alone stop the seat bending the clamp and tilting off the bracket?

John Forrest Tomlinson

On 11 Jun 2008 03:23:14 GMT, jobst.brandt@stanfordalumni.org wrote:

>John Forrest Tomlinson wrote:
>
>>>>>>> The same goes for seat post saddle clamps. If the single bolt
>>>>>>> fails, the rider falls onto the rotating rear wheel to produce an
>>>>>>> involuntary colostomy.
>
>>>> If the degree of danger if the bolt breaks varies with different
>>>> designs, I don't understand why you say "the rider falls" as if that
>>>> is a consistent outcome.
>
>>> You can only seriously say that having deleted what I had written and
>>> reinserted. I explained why the single bolt is hazardous and the
>>> difference between a heavy Schwinn attachment and a pseudo Campagnolo
>>> attachment that uses a single bolt the original size. I included the
>>> disclaimer: "I suspect these posts are the ones under discussion."
>
>>> From your comment I'm not convinced you are posting in good faith.
>>> Your question was anticipated and previously answered.
>
>> Here is what you wrote earlier:
>
>So why did you delete that from this response?

Because it wasn't relevant, but you were trying to make it lool like I
was up to somethign deceptive, which I wasn't. If you want to rag on
my usenet skills, go ahead, but you shouldn't assign motive to those
lack of skills.
> As you see, I
>reinserted that paragraph and you deleted it once more. You didn't
>have to get it from an earlier posting and add it here/
>>>
>
>>># That depends on how clever the design is. Old Schwinn balloon
>>># tired bicycles had single bolt clamps that with bolt failure the
>>># saddle could not fall away from under the rider as the current
>>># light weight designs "racing" do. Old Campagnolo Record posts
>>># had two bolts with which two bridge clamps allowed fore and aft
>>># sliding and by differential tightening adjust the fore and aft
>>># tilt.
>
>> You wrote "that depends on the design" after saying that "If the
>> single bolt fails, the rider falls onto the rotating rear wheel"
>
>That's why I mentoned old Schwinn design that does not present this
>hazard, thereby not making it dependent on one bolt but rather the
>design of that one bolt clamp.
>
>> Again, you made a definitive and comprehensive statement, and then
>> qualified it to apply to only some situations and not others. The
>> earlier statement was simply wrong in trying to be comprehensive.
>> That's all I'm saying and I'm saying it in quite good faith. And
>> laughing.
>
>You're creating your own entertainment at my expense.

Yes. The entertainment is that I point out a tiny inconsistency in
what you wrote, and you use the occasssion to suggest I was posting
"in bad faith." If by bad faith you mean trying to be deceptive,
you're wrong. The only "bad faith" is some small enjoyment is
pointing out a tiny error on your part. So I enjoy that? So what?

The single bolt
>seat clamps that are a derivative of the earlier Campagnolo Record
>seat post seemed to some to be an advance, but when the single bolt
>breaks, the saddle falls backward, the load of the sit bones being
>behind the pivot during at least part of the pedal stroke. This is
>not apparent to many in the business or its users, so I think it is
>worth mentioning the details.
>
>By bolt failure the saddle can drop to the ground and the rider, still
>attached to his pedals, land with his rectum on the rotating rear
>wheel. I know this from a couple of incidents, so I mentioned it.
>The injury was serious but repairable with emergency room sutures.
>
>You needn't defend the single bolt seat post here at my expense. I
>think there are better ways of discussing the merits of seat clamps
>than with ad hominem argumentation. I explained that these seat posts
>ignore the need for redundant bolts similar to stem and bar
>attachments, and that the danger is not apparent.

I'm not knowledgeable enough about engineering to comment on all of
the above, so I won't even try. I'm not even discussing the merits of
seatposts. I was simply pointing out that a bolt breaking doesn't
necessarily result in injury -- which you said it did, at first,
without qualification. If you want to try to disparage my statement
in some way to preserve your ego or make me look foolish, go ahead.
If I were in your situation, I'd simply let it go.

Tom Kunich

"John Forrest Tomlinson" <usenetremove@jt10000.com> wrote in message
news:ma7v445rubscfbagoutht0qadrnel4sk56@4ax.com...
>
> 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.

jim beam

Tom Kunich wrote:
> "John Forrest Tomlinson" <usenetremove@jt10000.com> wrote in message
> news:ma7v445rubscfbagoutht0qadrnel4sk56@4ax.com...
>>
>> 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.

John Forrest Tomlinson

On Wed, 11 Jun 2008 07:07:24 -0700, jim beam
<spamvortex@bad.example.net> wrote:

>Tom Kunich wrote:
>> "John Forrest Tomlinson" <usenetremove@jt10000.com> wrote in message
>> news:ma7v445rubscfbagoutht0qadrnel4sk56@4ax.com...
>>>
>>> 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.

Bill Sornson

Tom Kunich wrote:
> "John Forrest Tomlinson" <usenetremove@jt10000.com> wrote in message
> news:ma7v445rubscfbagoutht0qadrnel4sk56@4ax.com...
>>
>> 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.

JG

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

jim beam

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.

Tom Kunich

"Bill Sornson" <askme@ask.me> wrote in message
news:484fe580$0$12895$4c368faf@roadrunner.com...
> Tom Kunich wrote:
>> "John Forrest Tomlinson" <usenetremove@jt10000.com> wrote in message
>> news:ma7v445rubscfbagoutht0qadrnel4sk56@4ax.com...
>>>
>>> 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.

Bill Sornson

Tom Kunich wrote:
> "Bill Sornson" <askme@ask.me> wrote in message
> news:484fe580$0$12895$4c368faf@roadrunner.com...
>> Tom Kunich wrote:
>>> "John Forrest Tomlinson" <usenetremove@jt10000.com> wrote in message
>>> news:ma7v445rubscfbagoutht0qadrnel4sk56@4ax.com...
>>>>
>>>> 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.

John Forrest Tomlinson

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.

Tom Kunich

"John Forrest Tomlinson" <usenetremove@jt10000.com> wrote in message
news:v530545k1kgic5vt7pqv1i042g4i4vanpd@4ax.com...
>
> 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?