Curved Seat-Stays and Vibration/Shock absorption



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A

Alpine Rider

Guest
I'm wondering if curvy seat-stays really absorb any more road vibration versus straight seat stays
of the same material?

A few bike makers claim they do whiles others of course say there is no difference. I know the main
triangle doesn't flex much vertically but with those curvy seat stays like on litespeeds, sevens,
merlins do they bend a little more since the curve exposes them to more bending forces and allow a
slightly smoother ride?

Thanks

--
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/
 
M

Mike S.

Guest
"Alpine Rider" <[email protected]> wrote in message
news:eek:[email protected]...
> I'm wondering if curvy seat-stays really absorb any more road vibration versus straight seat stays
> of the same material?
>
> A few bike makers claim they do whiles others of course say there is no difference. I know the
> main triangle doesn't flex much vertically but
with
> those curvy seat stays like on litespeeds, sevens, merlins do they bend a little more since the
> curve exposes them to more bending forces and allow
a
> slightly smoother ride?
>
> Thanks
>

Oh, boy, this should be fun...

There's a discussion about frame materials and ride quality on rec.bicycles.misc right now that is
pretty much about this same question. Go look under "opinions on aluminum frames."

The engineers are at it again...

Mike
 
A

Alpine Rider

Guest
Thanks,

Actually I just saw a two year discussion that answered my question on google groups. I should have
searched more carefully before. It looks like this topic starts a holy war sometimes.

Sorry about the post if anyone is interested in the old discussion its at:

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=utf-8&threadm=3AA6CD70
.8254F587%40prodigy.net&rnum=4&prev=/groups%3Fq%3Dseat%2Bstay%2Bshock%2Babso
rption%26hl%3Den%26lr%3D%26ie%3DUTF-8%26oe%3Dutf-8%26selm%3D3AA6CD70.8254F58
7%2540prodigy.net%26rnum%3D4 "Mike S." <[email protected]> wrote in message
news:6%[email protected]...
> "Alpine Rider" <[email protected]> wrote in message
> news:eek:[email protected]...
> > I'm wondering if curvy seat-stays really absorb any more road vibration versus straight seat
> > stays of the same material?
> >
> > A few bike makers claim they do whiles others of course say there is no difference. I know the
> > main triangle doesn't flex much vertically but
> with
> > those curvy seat stays like on litespeeds, sevens, merlins do they bend
a
> > little more since the curve exposes them to more bending forces and
allow
> a
> > slightly smoother ride?
> >
> > Thanks
> >
>
>
>
> Oh, boy, this should be fun...
>
> There's a discussion about frame materials and ride quality on rec.bicycles.misc right now that is
> pretty much about this same question. Go look under "opinions on aluminum frames."
>
> The engineers are at it again...
>
> Mike
 
B

Bruce

Guest
Alpine Rider wrote:
> Thanks,
>
> Actually I just saw a two year discussion that answered my question on google groups. I should
> have searched more carefully before. It looks like this topic starts a holy war sometimes.

Anybody who thinks stays make good springs aint too bright. The flex is utterly insignificant
compared to the tires.

But then, some people believe in homeopathy, alien autopsies and a just world.
 
B

Bluto

Guest
"Mike S." <[email protected]> wrote:

> There's a discussion about frame materials and ride quality on rec.bicycles.misc right now that is
> pretty much about this same question. Go look under "opinions on aluminum frames."
>
> The engineers are at it again...

Say, you're that guy who can feel the difference between a steel bridge and a concrete one just by
walking on it, aren't you?

Chalo Colina

Ti bridges with carbon fiber stays are supple, yet responsive....
 
M

Mark Hickey

Guest
Alpine Rider <[email protected]> wrote:

>I'm wondering if curvy seat-stays really absorb any more road vibration versus straight seat stays
>of the same material?
>
>A few bike makers claim they do whiles others of course say there is no difference. I know the main
>triangle doesn't flex much vertically but with those curvy seat stays like on litespeeds, sevens,
>merlins do they bend a little more since the curve exposes them to more bending forces and allow a
>slightly smoother ride?

Nope. It's aesthetics only (well, that and perhaps a bit more heel clearance). I sell frames with
both straight and curved stays, so I have no dog in this hunt (though I get more money for the
curved stay model, so perhaps I should just shut up?). ;-)

Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame
 
M

Mark Hickey

Guest
[email protected] (Bluto) wrote:

>Say, you're that guy who can feel the difference between a steel bridge and a concrete one just by
>walking on it, aren't you?

I've heard you can tell (the steel bridge groans under your weight, while the concrete bridge just
kind of crackles...). ;-)

Mark "really glad I'm average size" Hickey Habanero Cycles http://www.habcycles.com Home of the
$695 ti frame
 
D

David L. Johnso

Guest
On Fri, 14 Mar 2003 20:14:38 -0500, Mike Latondresse wrote:

> Mark Hickey <[email protected]> wrote in news:[email protected]:
>
>
>> Nope. It's aesthetics only (well, that and perhaps a bit more heel clearance).
>
> Mark don't they curve down not up...I can't remember

In and out, for the chain stays. I have one of these, and my heel does not hit the stays, for what
that is worth.

But the modern curvy stays are nothing. Go find a picture of an old Hetchins. Aside from the
beautiful lugwork, their most apparent feature are the seriously curved stays. The seat stays start
out with an angle that would place them several inches ahead of the dropout, then curve back to it.
The seat stays curve up, I think, giving the appearance of some sort of suspension component. I
don't believe it worked -- if it did the rear brake wouldn't -- but it was striking.

--

David L. Johnson

__o | A mathematician is a machine for turning coffee into theorems. _`\(,_ | -- Paul Erdos
(_)/ (_) |
 
M

Mike S.

Guest
"Bluto" <[email protected]> wrote in message
news:[email protected]...
> "Mike S." <[email protected]> wrote:
>
> > There's a discussion about frame materials and ride quality on rec.bicycles.misc right now that
> > is pretty much about this same
question.
> > Go look under "opinions on aluminum frames."
> >
> > The engineers are at it again...
>
> Say, you're that guy who can feel the difference between a steel bridge and a concrete one just by
> walking on it, aren't you?
>
> Chalo Colina
>
>
> Ti bridges with carbon fiber stays are supple, yet responsive....

Now, wooden bridges I can tell by walking over. Steel and concrete hurt my feet too much.

Hell, I'm not convinced that the s bend stays do anything but look good either, but I get very tired
of people trying to "explain" things by testing in a lab, but not actually riding what they're
testing on the roads. As we all know, the difference between static testing in a lab, and dynamic
testing under actual conditions may indeed produce different data.

In the specific tests that are run in the lab, "you" may very well be correct in your assumptions
and conclusions. Frames do not flex vertically and wheels do flex vertically. Tires and pressures
account for more shock absorption than frames do, but is that all of the variables?

Riding a bike is definitely a dynamic thing. Every rotation of the crankset brings different
stresses on the bb/frame, wheels/tires, seat/seatpost, and every other part on the bike. As the
balance point changes, so do the stresses on all of the parts. It may not be much, but added all up,
there's gotta be something else going on that isn't being explained adequately.

I'm not saying I'm always right, in fact I could be wrong. But posting after me saying "yup, you're
a dumbass." isn't going to prove anything other than someone is 1. small minded and can't accept
criticism, or 2. refuses to think, or 3. is petty and vain and can't accept that their theories
aren't the most important to everyone else.

I don't have the time, money, or inclination to undertake the study that would be required to either
prove or disprove what I'm trying to convey. I'm going to go ride one of my 8 bikes and let y'all
think what you want to think.

Mike
 
S

Steve Palincsar

Guest
On Fri, 14 Mar 2003 18:20:00 -0500, Bluto wrote:

> Say, you're that guy who can feel the difference between a steel bridge and a concrete one just by
> walking on it, aren't you?

If you mean one of those notorious "cheese grater" steel bridges, you bet you can feel the
difference just by walking on it...
 
K

Kathy Hecht/Len

Guest
David L. Johnson said--- But the modern curvy stays are nothing. Go find a picture of an old
Hetchins. Aside from the beautiful lugwork, their most apparent feature are the seriously curved
stays. The seat stays start out with an angle that would place them several inches ahead of the
dropout, then curve back to it. The seat stays curve up, I think, giving the appearance of some sort
of suspension component. I don't believe it worked -- if it did the rear brake wouldn't -- but it
was striking.

I seem to remember the Hetchins curlystays had another commercial purpose. The race rules at
the time prohibited large lettering showing the manufacturer of the bike so making a very
obvious physical feature such as the curved stays was merely a way of advertising and selling
bikes. Len Diamond
 
D

David L. Johnso

Guest
On Sun, 16 Mar 2003 22:25:47 -0500, Kathy Hecht/Len Diamond wrote:

> David L. Johnson said--- But the modern curvy stays are nothing. Go find a picture of an old
> Hetchins. Aside from the beautiful lugwork, their most apparent feature are the seriously curved
> stays. The seat stays start out with an angle that would place them several inches ahead of the
> dropout, then curve back to it. The seat stays curve up, I think, giving the appearance of some
> sort of suspension component. I don't believe it worked -- if it did the rear brake wouldn't --
> but it was striking.
>
> I seem to remember the Hetchins curlystays had another commercial purpose. The race rules at
> the time prohibited large lettering showing the manufacturer of the bike so making a very
> obvious physical feature such as the curved stays was merely a way of advertising and selling
> bikes. Len Diamond

I had heard that, too, but mostly in reference to their lugs, which would extend half-way up the
stays in some instances. But this rule pre-dated my memory by many years (1950s in England, I
believe -- not my memory, the rule you referred to), and the curly stays persisted, and even got
more pronounced.

Also, it seems odd that only one company would use any sort of design to identify their bikes under
those conditions. The vast majority of racing bikes from that era would be indistinguishable from
one another without examination of subtle differences in lugs.

I recall one Hetchins in particular, which was a high-end touring frame with extremely curled stays.
The purported function had to have been suspension, but like I said, if it worked, the rear brake
would either hit the spokes or the tire.

--

David L. Johnson

__o | It is a scientifically proven fact that a mid life crisis can _`\(,_ | only be cured by
something racy and Italian. Bianchis and (_)/ (_) | Colnagos are a lot cheaper than Maserattis
and Ferraris. -- Glenn Davies
 
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