Single-Bolt Seatpost saddle slippage?

Andrew F Martin

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?

nora_lenderby@hotmail.com

On Jun 10, 7:47*am, Andrew F Martin <andrew.franklin.mar...@gmail.com>
wrote:

> I'm 180 and do tent to slide forward to the nose of the saddle
> (Arione) when I'm digging hard.

I think it's wonderful you're still riding (and gardening!) at your
advanced age - isn't modern medical technology astounding? - but have
you thought about trying one of these modern reclining bicycles?

Also, what a charming name you've given your saddle. My dear husband
used to teasingly call me Ariadne in his playful moments, though they
became rarer as the years advanced. He was always fond of Strauss.

Best wishes,

N Lenderby (Mrs)

* * Chas

"Andrew F Martin" <andrew.franklin.martin@gmail.com> wrote in message
news:bfedd0e4-5fa0-4896-9f52-f67fb8ca5520@d19g2000prm.googlegroups.com...
> 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?

Most single bolt seatpost suck! The ones with the serrations are difficult
to make minor adjustments and the other style tend to slip. There are
several dual bolt seatposts on the market with front/back adjustments. The
ones with one bolt one each side of the seatpost are rather useless for
making fine adjustments.

Chas.

jobst.brandt@stanfordalumni.org

Andrew F Martin 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?

A point one shouldn't overlook is failure consequences as with bar
stems on threadless steertubes. They need TWO clamp bolts on the
steertube and FOUR on the handlebar clamp so that a single bolt
failure will not leave the rider with no bars attached to the bicycle
in the middle of a high stress sprint.

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. This occurred locally and the outcome was a shock to
riders who heard of it and caused review of the matter of light
weight.

Jobst Brandt

bjw@mambo.ucolick.org

On Jun 10, 9:26*am, "* * Chas" <verktygj...@aol.spamski.com> wrote:
> "Andrew F Martin" <andrew.franklin.mar...@gmail.com> wrote in messagenews:bfedd0e4-5fa0-4896-9f52-f67fb8ca5520@d19g2000prm.googlegroups.com...
>
> > 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?
>
> Most single bolt seatpost suck! The ones with the serrations are difficult
> to make minor adjustments and the other style tend to slip. There are
> several dual bolt seatposts on the market with front/back adjustments. The
> ones with one bolt one each side of the seatpost are rather useless for
> making fine adjustments.

Yes, but. The OP has a Trek Madone, a machine suitable
for the most discerning of riders who require the ultimate in
aerodynamics. Especially if they've already got a fully
streamlined aerobelly. As such, once you get above a certain
level of Madone (5.1 or Gold Elite or Platinum Preferred Traveler
or something like that) it has an "aero" seatmast that doesn't
take a standard seatpost, as far as I can tell.

And people say there is no such thing as progress!

Ben

Tom Kunich

<jobst.brandt@stanfordalumni.org> wrote in message
news:484ed7fd$0$17235$742ec2ed@news.sonic.net...
>
> A point one shouldn't overlook is failure consequences as with bar
> stems on threadless steertubes. They need TWO clamp bolts on the
> steertube and FOUR on the handlebar clamp so that a single bolt
> failure will not leave the rider with no bars attached to the bicycle
> in the middle of a high stress sprint.
>
> 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. This occurred locally and the outcome was a shock to
> riders who heard of it and caused review of the matter of light
> weight.

I'd like to underscore Jobst's statements here since I came very close to a
serious injury less than a month ago due to something as silly as a clipless
pedal cleat having a funny wear pattern so that it gradually got so that it
disconnected with the slightest inward turn of the heal.

I'll eventually be as good as new according to several doctors but I'd
rather have never had such an accident.

John Forrest Tomlinson

On 10 Jun 2008 19:37:33 GMT, jobst.brandt@stanfordalumni.org 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.

For sure that's a potentially dangerous situation, but not quite as
definitely dangerous as you say. I've had it happen twice -- around
1992 and around 2002 and neither time did I hurt myself.

But yeah, reliablity in that area is important. The seatposts on my
bikes are now single bolt, but sturdier (I hope). At least the bolts
are bigger.

jobst.brandt@stanfordalumni.org

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.

> For sure that's a potentially dangerous situation, but not quite as
> definitely dangerous as you say. I've had it happen twice -- around
> 1992 and around 2002 and neither time did I hurt myself.

> But yeah, reliability in that area is important. The seatposts on
> my bikes are now single bolt, but sturdier (I hope). At least the
> bolts are bigger.

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.

This attachment was reduced to a single bolt by others at a later date
without anyone questioning its safety and failure mode. I suspect
these posts are the ones under discussion.

Jobst Brandt

John Forrest Tomlinson

On 11 Jun 2008 00:09:03 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.
>
>> For sure that's a potentially dangerous situation, but not quite as
>> definitely dangerous as you say. I've had it happen twice -- around
>> 1992 and around 2002 and neither time did I hurt myself.
>
>> But yeah, reliability in that area is important. The seatposts on
>> my bikes are now single bolt, but sturdier (I hope). At least the
>> bolts are bigger.
>
>That depends on how clever the design is.

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.

JT

jobst.brandt@stanfordalumni.org

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.

>>> For sure that's a potentially dangerous situation, but not quite
>>> as definitely dangerous as you say. I've had it happen twice --
>>> around 1992 and around 2002 and neither time did I hurt myself.

>>> But yeah, reliability in that area is important. The seatposts on
>>> my bikes are now single bolt, but sturdier (I hope). At least the
>>> bolts are bigger.

>> 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.

>> This attachment was reduced to a single bolt by others at a later
>> date without anyone questioning its safety and failure mode. I
>> suspect these posts are the ones under discussion.

> 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.

Jobst Brandt

John Forrest Tomlinson

On 11 Jun 2008 00:47:55 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:

> 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"

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.

jim beam

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.
>
>>>> For sure that's a potentially dangerous situation, but not quite
>>>> as definitely dangerous as you say. I've had it happen twice --
>>>> around 1992 and around 2002 and neither time did I hurt myself.
>
>>>> But yeah, reliability in that area is important. The seatposts on
>>>> my bikes are now single bolt, but sturdier (I hope). At least the
>>>> bolts are bigger.
>
>>> 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.
>
>>> This attachment was reduced to a single bolt by others at a later
>>> date without anyone questioning its safety and failure mode. I
>>> suspect these posts are the ones under discussion.
>
>> 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.

but jobst, you contradict yourself. upstream you say: "the saddle could
not fall away from under the rider as the current light weight designs
"racing" do." well, i've looked at every single one of my "racing" seat
posts, and not a single one will allow the seat to "fall away" in the
event of bolt breakage because the bottom cradle rests in compression on
the post head.

could it possibly be that you're contemplating some dim and distant
memory of some design you once saw and are using that as criticism for
the last 30 years of seat posts? because that would be entirely in
character with some of your other bizarre rants about equipment you
don't own or use.

how many brands do you possess btw? and how old are they? i ask
because every single one of the campy, ritchie, easton, weyless, or
other cheapo nameless brands i possess all have the cradle in
compression against the head.

oh, and on the subject of bolt breakage, the only bending or tensile
load on that bolt is from seat tilting. unless the seat is mounted at
the extreme of one or other end of its rails, there's not much fatigue
load. but you'd see that if you actually possessed a modern seat post.
or could be bothered to look at one.

jobst.brandt@stanfordalumni.org

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? 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. 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.

Jobst Brandt

jim beam

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? 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. 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.

"not apparent" is somewhat presumptive given that you attribute it to
all and sundry who may actually have bothered to contemplate such
matters. what's much more "not apparent" however is whether you're
prepared to address this single bolt's loading mode and discuss its real
world failure statistics. observation of manufacturer's torque spec
should enter into your discussion.


>
> 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.

you repeat [not just here, but have done so many times] this clinical
detail as if it's more important than potential femoral artery rupture
or testicular laceration. do you have some kind of proctological
interest in that particular injury? i mean, it's ok here in the bay
area you know.

> 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.

eh? and why say it twice?


> I
> think there are better ways of discussing the merits of seat clamps
> than with ad hominem argumentation.

the only person here getting close to ad hominem is you. jft simply
pointed out that your typically jobstian "definitive and comprehensive
statement" required qualification, and thus was not a "definitive and
comprehensive statement" at all. if you think thats personal attack,
you're losing the plot.


> 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.

how much redundancy do you need jobst? two front forks? two pedal
spindles each side? two crank arms each side? two brake levers each
side? double brake cables front and rear? two seat post tubes? we
gave up on biplanes years ago jobst - you can look for other ogres under
your bed.