integrating seat tube and seat post?

Hello,

Let's say you were to buy a custom fit bike. Would there be any advantage in, instead of having a
saddle mounted on a seat post, carrying on the seat tube to the desired height and mounting, via
some attachment, the saddle on to that?

* Would it be lighter - no seat post pin or tubing overlap?

* Immune to problem of frame filling with water via seat post if saddle attahment were designed
carefully?

* safer? Less likely to snap?

I'd be really interested to hear people's thoughts!

Cheers

Daniel

 

"Daniel Parry" <[email protected]> wrote in message
news:[email protected]...
> Hello,
>
> Let's say you were to buy a custom fit bike. Would there be any advantage in, instead of having a
> saddle mounted on a seat post, carrying on the seat tube to the desired height and mounting, via
> some attachment, the saddle on to that?

How would you cope with different height shoes? Eg my winter boots require the saddle to be slightly
higher than my summer shoes.

cheers, clive

 

On Fri, 07 Mar 2003 20:32:56 +0000, Daniel Parry did issue forth:

> Hello,
>
> Let's say you were to buy a custom fit bike. Would there be any advantage in, instead of having a
> saddle mounted on a seat post, carrying on the seat tube to the desired height and mounting, via
> some attachment, the saddle on to that?
>
> * Would it be lighter - no seat post pin or tubing overlap?

This is true, you'd get rid of the binder and the bit where the tube and post overlap thus
reducing weight.

> * Immune to problem of frame filling with water via seat post if saddle attahment were designed
> carefully?

Yes, but we'd be assuming that you don't get water in through other places like the headset and
bottom bracket.

> * safer? Less likely to snap?

Potentially, but if it did snap it would be a swine to replace.

I think the big problem here is that people do need to adjust saddle heights. Look at a range of
saddles in a bike shop and you'll see that they all have different heights from the rails to the top
of the seat. You'd have to stick with one type of saddle with a bike like that.

--
Huw Pritchard Replace bounce with huw to reply by mail

 

news:[email protected]...
> "Daniel Parry" <[email protected]> wrote in message
> news:[email protected]...
> > Hello,
> >
> > Let's say you were to buy a custom fit bike. Would there be any
advantage
> > in, instead of having a saddle mounted on a seat post, carrying on the seat tube to the desired
> > height and mounting, via some attachment, the saddle on to that?
>
> How would you cope with different height shoes? Eg my winter boots require the saddle to be
> slightly higher than my summer shoes.
>
> cheers, clive
>
>

Different pedals have different stack heights too.

I would certainly want an adjustable post. Even after having a pro bike fit I still made minute
adjustments to my saddle every now and then...when you spend hours on the road even a few
millimetres can be felt.

I can't think of any advantage of the extension, except maybe for a few grams in weight?

--
Mark
______________________________________

"Just ask yourself: What would Scooby Doo?"

 

In article <[email protected]>, Clive George wrote:
> How would you cope with different height shoes? Eg my winter boots require the saddle to be
> slightly higher than my summer shoes.

Silly answers:
* Two slightly different sized custom frames ^_-
* Slightly different length cranks ^_^

Slightly more sensible answer: Personally I don't have that problem as I would use the same shoes in
winter fitted with some kind of overshoe rather than change shoes entirely. I would also suggest
that you might use a winter 'hack' bike and then bring the custom build out (e.g. it might be a time
trial bike or some such) for the warmer months.

Cheers

Daniel

 

In article <[email protected]>, MSA wrote:
> I would certainly want an adjustable post. Even after having a pro bike fit I still made minute
> adjustments to my saddle every now and then...when you spend hours on the road even a few
> millimetres can be felt.

Maybe the seat attachment device could be designed to allow the necessary few milimetres adjustment
either way without the need for the many cm of seat post / seat tube overlap. Admittedly I don't
know how. Perhaps you could adjust a screw in a specially made saddle that raises / lowers the
saddle rails by a few mm?

Cheers

Daniel

 

[email protected] schreef ...
> In article <[email protected]>, MSA wrote:
> > I would certainly want an adjustable post. Even after having a pro bike fit I still made minute
> > adjustments to my saddle every now and then...when you spend hours on the road even a few
> > millimetres can be felt.
>
> Maybe the seat attachment device could be designed to allow the necessary few milimetres
> adjustment either way without the need for the many cm of seat post / seat tube overlap.
> Admittedly I don't know how. Perhaps you could adjust a screw in a specially made saddle that
> raises / lowers the saddle rails by a few mm?

And all this for what? The slightly unlikely event of a seatpost snapping? Stopping some of the
water intrusion? It sounds like finding a solution to a problem that doesn't really exist .....

--
Regards, Marten

 

Daniel Parry <[email protected]> wrote:
>
> Maybe the seat attachment device could be designed to allow the necessary few milimetres
> adjustment either way without the need for the many cm of seat post / seat tube overlap.
> Admittedly I don't know how. Perhaps you could adjust a screw in a specially made saddle that
> raises / lowers the saddle rails by a few mm?
>

It would be easy enough to do. Just mount the seat on a short cylindrical post that can slide up and
down inside the seat tube and add a bolt to clamp it in place. Can't think why no-one has thought of
it before ;-)

Tony

--
http://www.raven-family.com

"I don't want any yes-men around me. I want everybody to tell me the truth even if it costs them
their job."

Samuel Goldwyn

 

Daniel Parry wrote:
> Let's say you were to buy a custom fit bike. Would there be any advantage in, instead of having a
> saddle mounted on a seat post, carrying on the seat tube to the desired height and mounting, via
> some attachment, the saddle on to that?

Chris Boardman had a bike made like that for aerodynamic reasons - but it's not practical for normal
cycling for us mere mortals. It's very important that seat height is adjustable because:
1) The builder probably wouldn't get it _exactly_ right for you in the first place, first time
(a couple of mm does make a difference).
2) May need to change when using different pedals, shoes, extra-padded trousers!, etc, etc, etc,
etc, etc, etc, and most importantly, different saddles (they vary a great deal in height).
3) May need to change height if decide to put saddle forwards or back.
4) What about when someone else uses/buys your bike?

> * Would it be lighter - no seat post pin or tubing overlap?

I'm not sure. Tubing might have to be more oversized and/or thickened. Not having excess length
would help, though.

> * Immune to problem of frame filling with water via seat post if saddle attahment were designed
> carefully?

Maybe but that problem can be avoided anyway or isn't important.

> * safer? Less likely to snap?

No. Good sensible seatposts rarely snap, and I would be worried about the seat tube snapping just as
much or more than about a seatpost.

> I'd be really interested to hear people's thoughts!

It's an interesting idea but a crap one. Sorry! Adjustabity is being taken away from us enoug as
it is (think ahead stems) so I wouldn't want to be unable to adjust saddle height as well.

However, I wouldn't mind if someone could come up with a design to make seatposts (even) easier to
adjust and centre (I hate having to rely on eyeballs).

--
~PB FA: 62cm Ti frame: http://tinyurl.com/6stt

 

In article <[email protected]>, Marten Hoffmann wrote:
> And all this for what?

A cheaper way of saving weight on a bike than spending large amounts of cash on some exotic frame
material? Judging to the lengths the riders go to reduce bike weight, I suspect some in the TDF
would be glad of the extra weight saving on the mountain stages, for example?

> The slightly unlikely event of a seatpost snapping? Stopping some of the water intrusion? It
> sounds like finding a solution to a problem that doesn't really exist .....

But the, admittedly unlikely, problems _do_ exists? Would it not be nice to reduce / eradicate such?

 

In article <[email protected]>, Pete Biggs wrote:
> Chris Boardman had a bike made like that for aerodynamic reasons - but it's not practical for
> normal cycling for us mere mortals. It's very important that seat height is adjustable because:
> 1) The builder probably wouldn't get it _exactly_ right for you in the first place, first time
> (a couple of mm does make a difference).

Ok, fair enough but am I right in saying a decent builder could build to within 1-2 mm?

> 2) May need to change when using different pedals, shoes, extra-padded trousers!, etc, etc,
> etc, etc, etc, etc, and most importantly, different saddles (they vary a great deal in
> height).
> 3) May need to change height if decide to put saddle forwards or back.

I think my argument now rests on the assumption that you could design a saddle attachment that would
allow (say) 6mm of height adjustment, without the need for seat post / seat tube overlap. I would
argue that if this were possible it would be sufficient to deal with clothing height alterations. As
for variation in saddle heights, perhaps it would be possible, if you're going for a custom built
bike, to know which saddle you are happy with and be prepared to stick with that model or similar
whilst using the bike?

> 4) What about when someone else uses/buys your bike?

Saddle height is just one factor in bike fit. They would obviously need to be a similar size with
only 6mm of play in seat height (though they could use a different saddle to raise / lower the
height a little more). But then the reach is unlikely to be perfect, or the handle bar width
ideal... etc. If you buy a bike, the fit is rarely perfect but is often good enough

> I'm not sure. Tubing might have to be more oversized and/or thickened.

Is seat post tubing thicker / stronger than seat tube tubing? Does the fact that you have only
one tube mean you can get away with a weaker tubing or does the tubing overlap of the seat post
add strength?

> Maybe but that problem can be avoided anyway or isn't important.

Yes it would only be a minor factor but every little helps.

> No. Good sensible seatposts rarely snap, and I would be worried about the seat tube snapping just
> as much or more than about a seatpost.

Even a good sensible seat tube? ^_-

> It's an interesting idea but a crap one. Sorry!

^_^

> Adjustabity is being taken away from us enoug as it is (think ahead stems)

Never used one. I take it you mean adjustability of height of them? Need to use spacers etc. Fact
is, many people use them despite this difficulty for some reason - weight perhaps? Not so different
from my idea then?

> However, I wouldn't mind if someone could come up with a design to make seatposts (even) easier to
> adjust and centre (I hate having to rely on eyeballs).

Vertical lines drawn along seat post?

 

In article <[email protected]>, Huw Pritchard wrote:
> On Fri, 07 Mar 2003 20:32:56 +0000, Daniel Parry did issue forth:
>> * Would it be lighter - no seat post pin or tubing overlap?
>
> This is true, you'd get rid of the binder and the bit where the tube and post overlap thus
> reducing weight.

Which is a good thing!

>> * Immune to problem of frame filling with water via seat post if saddle attahment were designed
>> carefully?
>
> Yes, but we'd be assuming that you don't get water in through other places like the headset and
> bottom bracket.

Is it possible for water entering via the headset to get into the top tube /down tube? It is limited
to the head tube right? and so not as bad as having water in the main part of the frame? And water
entering via bb is surely even less likely than via seat post, right?

> Potentially, but if it did snap it would be a swine to replace.

Might be able to salvage depending how far along it snapped? How well a length of tubing can be
manufactured would be a factor in deciding the likelihood of snapping?

> I think the big problem here is that people do need to adjust saddle heights. Look at a range of
> saddles in a bike shop and you'll see that they all have different heights from the rails to the
> top of the seat. You'd have to stick with one type of saddle with a bike like that.

Is that such a bad thing? A lot of people swear by one particular make of saddle? If you're going to
the lengths of buying a custom bike you would know / thought about what saddle you like?

 

Daniel Parry wrote:
> In article <[email protected]>, Pete Biggs wrote:
>> Chris Boardman had a bike made like that for aerodynamic reasons - but it's not practical for
>> normal cycling for us mere mortals. It's very important that seat height is adjustable because:
>> 1) The builder probably wouldn't get it _exactly_ right for you in the first place, first
>> time (a couple of mm does make a difference).
>
> Ok, fair enough but am I right in saying a decent builder could build to within 1-2 mm?

Yes I suppose so if the customer was sure about what they needed.

> I think my argument now rests on the assumption that you could design a saddle attachment that
> would allow (say) 6mm of height adjustment, without the need for seat post / seat tube overlap. I
> would argue that if this were possible it would be sufficient to deal with clothing height
> alterations.

What form would the attachment take? It would be quite difficult to better the simple design of
a seatpost.

> As for variation in saddle heights, perhaps it would be possible, if you're going for a custom
> built bike, to know which saddle you are happy with and be prepared to stick with that model or
> similar whilst using the bike?

Many people do always stick with the same saddle, but that still leaves plenty who would want the
freedom to change model - even if they had a custom made bike.

>> I'm not sure. Tubing might have to be more oversized and/or thickened.
>
> Is seat post tubing thicker / stronger than seat tube tubing?

Very much so (with conventional diamond frames at least). Usually, much, much thicker and stronger
because it's supported only at one end. The seat tube is part of a triangle so doesn't have to be so
strong. Some frame tube walls are hardly thicker than those of a Coke can. You wouln't want to perch
on a pole of that, would you.

> Does the fact that you have only one tube mean you can get away with a weaker tubing

No, the opposite.

> or does the tubing overlap of the seat post add strength?

Yes.

>> Good sensible seatposts rarely snap, and I would be worried about the seat tube snapping just as
>> much or more than about a seatpost.
>
> Even a good sensible seat tube? ^_-

I wouldn't worry if the special seat tube was as strong as a conventional arrangement but I bet that
would then be (almost) as heavy!

>> Adjustabity is being taken away from us enoug as it is (think ahead stems)
>
> Never used one. I take it you mean adjustability of height of them?

Yes.

> Need to use spacers etc. Fact is, many people use them despite this difficulty for some reason -
> weight perhaps?

Because that's what we're being fed by the manufacturers - we're getting less and less choice about
over matter: look what new bikes come with now. The threadless system is cheaper* with more choice
of stems & headsets on the aftermarket now - as well as arguably being lighter and stiffer.

I like some aspects of it a lot, but adjusting height is defintely extra hassle - so much so that
many users never adjust at all, and some are even put off cycling for good because they have the
wrong height bars and don't think they can do anything about it. (Fork steerers being cut too short
is part of the problem as well: often stem at maximum height is simply too low).

* Cheaper and easier for the manufacturer because stems and headsets are simpler, forks don't need
threading, etc.

> Not so different from my idea then?

No indeed, except I'm not convinced that there would be enough advantage in the idea to justify it
for anyone other than specialist competition cyclists. I seriously do not want to loose any more
adjustability so I hope your idea never catches on.

>> However, I wouldn't mind if someone could come up with a design to make seatposts (even) easier
>> to adjust and centre (I hate having to rely on eyeballs).
>
> Vertical lines drawn along seat post?

That would help! Cheers.

--
~PB FA: 62cm Ti frame: http://tinyurl.com/6stt

 

[email protected] schreef ...

> Is it possible for water entering via the headset to get into the top tube /down tube? It is
> limited to the head tube right? and so not as bad as having water in the main part of the frame?
> And water entering via bb is surely even less likely than via seat post, right?

Water also enters through the bottleholder bolts .........

> Is that such a bad thing? A lot of people swear by one particular make of saddle? If you're going
> to the lengths of buying a custom bike you would know / thought about what saddle you like?

Of course you would. But perhaps your riding habits change over the years. Or your favorite saddle
suffers damage in a crash and it is no longer being made. Or you want to sell the bike on one day to
get a new custom-built one. Especially in the last case you would have to find somebody with
*exactly* your measurements.

In all: deleting the seatpost seems to me an extremely difficult way to solve a practically
non-existent problem.

--
Regards, Marten

 

On Fri, 07 Mar 2003 15:32:56 -0500, Daniel Parry wrote:

> Hello,
>
> Let's say you were to buy a custom fit bike. Would there be any advantage in, instead of having a
> saddle mounted on a seat post, carrying on the seat tube to the desired height and mounting, via
> some attachment, the saddle on to that?
>
> * Would it be lighter - no seat post pin or tubing overlap?
>
> * Immune to problem of frame filling with water via seat post if saddle attahment were designed
> carefully?
>
> * safer? Less likely to snap?
>
> I'd be really interested to hear people's thoughts!

You'd still need something to hold the saddle. These are commercially available: they are made onto
the end of seat posts. They don't, as far as I know, come separately without the post.

A seat post needs to be inserted some minimum distance into the seat tube in order to avoid damaging
stresses, so if you intend to use one of these widely available devices you are going to have to use
it as a (possibly shortened) seat post. I'm sure you can't just weld the head onto the top of the
seat lug and expect it to not break off.

This sounds to me a lot like an ill-conceived solution in search of a non-existent problem.