Info from wheelbuilder.com site

[Mike Jacoubowsky]

http://www.wheelbuilder.com/tips/Spokes.asp
"As the number of spoke crossings increase the angle in which each spoke
leaves the hub approaches 90o (tangential). Wheels with 3x or 4x lace
patterns will usually transfer power more efficiently than those with 2x
patterns. As the number of spoke crossings increase the length of each spoke
increases. Longer spokes are more flexible and contribute to decreased
radial stiffness, which improves ride quality. Consequently wheels with
more spoke crossings have lower lateral stiffness, which is important to
cornering stability."

#1: Does a difference in spoke length from, say, 288mm to 302mm, which is
about 5%, actually contribute to a difference you can feel?

#2: How does "lower lateral stiffness" improve cornering stability?

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

 

[Qui si parla Campagnolo]

Who are these knuckleheads??

Mike Jacoubowsky wrote:
> http://www.wheelbuilder.com/tips/Spokes.asp
> "As the number of spoke crossings increase the angle in which each spoke
> leaves the hub approaches 90o (tangential). Wheels with 3x or 4x lace
> patterns will usually transfer power more efficiently than those with 2x
> patterns. As the number of spoke crossings increase the length of each spoke
> increases. Longer spokes are more flexible and contribute to decreased
> radial stiffness, which improves ride quality. Consequently wheels with
> more spoke crossings have lower lateral stiffness, which is important to
> cornering stability."
>
> #1: Does a difference in spoke length from, say, 288mm to 302mm, which is
> about 5%, actually contribute to a difference you can feel?
>
> #2: How does "lower lateral stiffness" improve cornering stability?
>
> --Mike-- Chain Reaction Bicycles
> www.ChainReactionBicycles.com

 

[jim beam]

Mike Jacoubowsky wrote:
> http://www.wheelbuilder.com/tips/Spokes.asp
> "As the number of spoke crossings increase the angle in which each spoke
> leaves the hub approaches 90o (tangential). Wheels with 3x or 4x lace
> patterns will usually transfer power more efficiently than those with 2x
> patterns. As the number of spoke crossings increase the length of each spoke
> increases. Longer spokes are more flexible and contribute to decreased
> radial stiffness, which improves ride quality. Consequently wheels with
> more spoke crossings have lower lateral stiffness, which is important to
> cornering stability."
>
> #1: Does a difference in spoke length from, say, 288mm to 302mm, which is
> about 5%, actually contribute to a difference you can feel?

you mean the difference between radial and tangential spoking? some
people say they can feel it. others not. does it matter?

>
> #2: How does "lower lateral stiffness" improve cornering stability?

it doesn't actually say "it improves it", it says lateral stiffness is
important, but doesn't state the sense. lateral stiffness /can/ be
important if the rider jockeys or the frame is not very stiff
torsionally [shimmy], and stiffer is better.

i guess your objective in this post is to illustrate misinformation
and/or ambiguity. if so, do you have a position on the subject or do
you just want to stir the pot?

 

[[email protected]]

On Sun, 07 Jan 2007 18:40:42 GMT, "Mike Jacoubowsky"
<[email protected]> wrote:

>http://www.wheelbuilder.com/tips/Spokes.asp
>"As the number of spoke crossings increase the angle in which each spoke
>leaves the hub approaches 90o (tangential). Wheels with 3x or 4x lace
>patterns will usually transfer power more efficiently than those with 2x
>patterns. As the number of spoke crossings increase the length of each spoke
>increases. Longer spokes are more flexible and contribute to decreased
>radial stiffness, which improves ride quality. Consequently wheels with
>more spoke crossings have lower lateral stiffness, which is important to
>cornering stability."
>
>#1: Does a difference in spoke length from, say, 288mm to 302mm, which is
>about 5%, actually contribute to a difference you can feel?
>
>#2: How does "lower lateral stiffness" improve cornering stability?
>
>--Mike-- Chain Reaction Bicycles
>www.ChainReactionBicycles.com

Dear Mike,

Damon Rinard has tested 140 wheels for lateral stiffness by mounting
them horizontally in a machine table rig, hanging a 25-lb weight, and
measuring how far the rim drops with a micrometer:

http://www.sheldonbrown.com/rinard/wheel/data.htm

He points out that this 25-lb force is more than the wheel is likely
to experience in cornering.

The wheels deflect only 0.97 to 5.23 mm with this heavy lateral load.

Most wheels tested are around 2 mm (the 5.23 mm is an oddball plastic
spoked wheel), so the typical difference is about 1 mm.

It's unlikely that any rider could tell any difference between the
wheels in blind testing of cornering (hard to arrange blindness with a
wheel, but big fenders might work wonders).

The page is well worth a look.

Cheers,

Carl Fogel

 

[Tim McNamara]

In article <[email protected]>,
"Mike Jacoubowsky" <[email protected]> wrote:

> http://www.wheelbuilder.com/tips/Spokes.asp "As the number of spoke
> crossings increase the angle in which each spoke leaves the hub
> approaches 90o (tangential). Wheels with 3x or 4x lace patterns will
> usually transfer power more efficiently than those with 2x patterns.
> As the number of spoke crossings increase the length of each spoke
> increases. Longer spokes are more flexible and contribute to
> decreased radial stiffness, which improves ride quality.
> Consequently wheels with more spoke crossings have lower lateral
> stiffness, which is important to cornering stability."
>
> #1: Does a difference in spoke length from, say, 288mm to 302mm,
> which is about 5%, actually contribute to a difference you can feel?
>
> #2: How does "lower lateral stiffness" improve cornering stability?

Wait, it gets better:

"Tension is simply the load applied to spokes by tightening the
nipples. Consider each spoke to be a long slender bolt connecting the
hub to the rim with a fastening nut called the nipple. Spokes behave
similar to bolts in that they stretch and use the energy held in the
material to resists the complex dynamic loads created by the rider and
the road. Spoke tension cannot be determined by visually inspecting a
wheel and is often independent of wheel trueness. Evaluation and
balancing of spoke tension with a Tensiometer can be time consuming and
add very little to the aesthetic trueness of a wheel. For this reason
spoke tension is neglected by many bicycle mechanics. Wheelbuilder
carefully monitors spoke tension during our build process to ensure an
even distribution of load through the entire wheel structure. During
the final truing process all spoke tensions are input into our own
software for a statistical comparison. We do not ship wheels with
spoke tension variations outside of our close tolerance. A well
balanced hand built wheel will outperform and outlast any machine built
wheel. Additionally it will feel more responsive and stay true for
thousands of miles."

A mix of accurate statements and mumbo-jumbo, which is to be found
throughout the site. Yikes.

 

[Qui si parla Campagnolo]

Mike Jacoubowsky wrote:
> http://www.wheelbuilder.com/tips/Spokes.asp
> "As the number of spoke crossings increase the angle in which each spoke
> leaves the hub approaches 90o (tangential). Wheels with 3x or 4x lace
> patterns will usually transfer power more efficiently than those with 2x
> patterns. As the number of spoke crossings increase the length of each spoke
> increases. Longer spokes are more flexible and contribute to decreased
> radial stiffness, which improves ride quality. Consequently wheels with
> more spoke crossings have lower lateral stiffness, which is important to
> cornering stability."
>
> #1: Does a difference in spoke length from, say, 288mm to 302mm, which is
> about 5%, actually contribute to a difference you can feel?
>
> #2: How does "lower lateral stiffness" improve cornering stability?
>
> --Mike-- Chain Reaction Bicycles
> www.ChainReactionBicycles.com

Hype nowithstanding, goods and others about the site-

-wheelbuilders-good
-pricing-not bad altho only 14g straight DT spokes PLUS $.09 for brass
nipps(they come with the spokes)
-lots of choices-good altho sounds like they'll build anything,
regardless of how silly
-hub choices-disappointing..DT, good, BUT none of the best hubs there
are-Campagnolo and shimano

I think anybody that still builds wheels, from scratch, is good. And if
people will listen, they will learn the resulting wheels are big on
performance, reliability but low on hype and price.

 

[Mike Jacoubowsky]

>> #2: How does "lower lateral stiffness" improve cornering stability?
>
> it doesn't actually say "it improves it", it says lateral stiffness is
> important, but doesn't state the sense. lateral stiffness /can/ be
> important if the rider jockeys or the frame is not very stiff torsionally
> [shimmy], and stiffer is better.
>
> i guess your objective in this post is to illustrate misinformation and/or
> ambiguity. if so, do you have a position on the subject or do you just
> want to stir the pot?

No, my objective was to find out what people thought about the idea that
too-much lateral stiffness is a bad thing. This is a new one to me. To the
best of my knowledge, people here and elsewhere have tended towards
stiffer=stronger=better for most things having to do with wheels.
Intuitively, I'd think that lateral stiffness would enhance cornering. But
re-reading the paragraph in question-

"As the number of spoke crossings increase the length of each spoke
increases. Longer spokes are more flexible and contribute to decreased
radial stiffness, which improves ride quality. Consequently wheels with
more spoke crossings have lower lateral stiffness, which is important to
cornering stability."

- Perhaps I had it backward, and they're saying that lateral stiffness, not
lower lateral stiffness, is a good thing?

I have my own opinions, but I learn a lot more when I listen to what other
people have to say about something than when I'm trying to defend myself.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com



"jim beam" <[email protected]> wrote in message
news:[email protected]...
> Mike Jacoubowsky wrote:
>> http://www.wheelbuilder.com/tips/Spokes.asp
>> "As the number of spoke crossings increase the angle in which each spoke
>> leaves the hub approaches 90o (tangential). Wheels with 3x or 4x lace
>> patterns will usually transfer power more efficiently than those with 2x
>> patterns. As the number of spoke crossings increase the length of each
>> spoke increases. Longer spokes are more flexible and contribute to
>> decreased radial stiffness, which improves ride quality. Consequently
>> wheels with more spoke crossings have lower lateral stiffness, which is
>> important to cornering stability."
>>
>> #1: Does a difference in spoke length from, say, 288mm to 302mm, which is
>> about 5%, actually contribute to a difference you can feel?
>
> you mean the difference between radial and tangential spoking? some
> people say they can feel it. others not. does it matter?
>
>>
>> #2: How does "lower lateral stiffness" improve cornering stability?
>
> it doesn't actually say "it improves it", it says lateral stiffness is
> important, but doesn't state the sense. lateral stiffness /can/ be
> important if the rider jockeys or the frame is not very stiff torsionally
> [shimmy], and stiffer is better.
>
> i guess your objective in this post is to illustrate misinformation and/or
> ambiguity. if so, do you have a position on the subject or do you just
> want to stir the pot?

 

[Gary Young]

On Mon, 08 Jan 2007 00:55:34 +0000, Mike Jacoubowsky wrote:

>>> #2: How does "lower lateral stiffness" improve cornering stability?
>>
>> it doesn't actually say "it improves it", it says lateral stiffness is
>> important, but doesn't state the sense. lateral stiffness /can/ be
>> important if the rider jockeys or the frame is not very stiff
>> torsionally [shimmy], and stiffer is better.
>>
>> i guess your objective in this post is to illustrate misinformation
>> and/or ambiguity. if so, do you have a position on the subject or do
>> you just want to stir the pot?
>
> No, my objective was to find out what people thought about the idea that
> too-much lateral stiffness is a bad thing. This is a new one to me. To
> the best of my knowledge, people here and elsewhere have tended towards
> stiffer=stronger=better for most things having to do with wheels.
> Intuitively, I'd think that lateral stiffness would enhance cornering.
> But re-reading the paragraph in question-
>
> "As the number of spoke crossings increase the length of each spoke
> increases. Longer spokes are more flexible and contribute to decreased
> radial stiffness, which improves ride quality. Consequently wheels with
> more spoke crossings have lower lateral stiffness, which is important to
> cornering stability."
>
> - Perhaps I had it backward, and they're saying that lateral stiffness,
> not lower lateral stiffness, is a good thing?
>
> I have my own opinions, but I learn a lot more when I listen to what
> other people have to say about something than when I'm trying to defend
> myself.
>
> --Mike-- Chain Reaction Bicycles
> www.ChainReactionBicycles.com
>
>
I don't think this idea is entirely novel (which is not to say that it has
any merit).

I used to have a wheelbuilding book that made a similar claim. I think
this is it, though I can't be sure without seeing the cover:

http://tinyurl.com/yehrz7

The book had two drawings of a swimmer bouncing on the end of a diving
board. In one, the board was short; in the other, long. One could see from
the cartoon motion marks that the long board was deflecting more. The
author's conclusion was that long spokes are cushier.



> "jim beam" <[email protected]> wrote in message
> news:[email protected]...
>> Mike Jacoubowsky wrote:
>>> http://www.wheelbuilder.com/tips/Spokes.asp "As the number of spoke
>>> crossings increase the angle in which each spoke leaves the hub
>>> approaches 90o (tangential). Wheels with 3x or 4x lace patterns will
>>> usually transfer power more efficiently than those with 2x patterns.
>>> As the number of spoke crossings increase the length of each spoke
>>> increases. Longer spokes are more flexible and contribute to
>>> decreased radial stiffness, which improves ride quality. Consequently
>>> wheels with more spoke crossings have lower lateral stiffness, which
>>> is important to cornering stability."
>>>
>>> #1: Does a difference in spoke length from, say, 288mm to 302mm, which
>>> is about 5%, actually contribute to a difference you can feel?
>>
>> you mean the difference between radial and tangential spoking? some
>> people say they can feel it. others not. does it matter?
>>
>>
>>> #2: How does "lower lateral stiffness" improve cornering stability?
>>
>> it doesn't actually say "it improves it", it says lateral stiffness is
>> important, but doesn't state the sense. lateral stiffness /can/ be
>> important if the rider jockeys or the frame is not very stiff
>> torsionally [shimmy], and stiffer is better.
>>
>> i guess your objective in this post is to illustrate misinformation
>> and/or ambiguity. if so, do you have a position on the subject or do
>> you just want to stir the pot?

 

[jim beam]

Mike Jacoubowsky wrote:
>>> #2: How does "lower lateral stiffness" improve cornering stability?
>> it doesn't actually say "it improves it", it says lateral stiffness is
>> important, but doesn't state the sense. lateral stiffness /can/ be
>> important if the rider jockeys or the frame is not very stiff torsionally
>> [shimmy], and stiffer is better.
>>
>> i guess your objective in this post is to illustrate misinformation and/or
>> ambiguity. if so, do you have a position on the subject or do you just
>> want to stir the pot?
>
> No, my objective was to find out what people thought about the idea that
> too-much lateral stiffness is a bad thing. This is a new one to me. To the
> best of my knowledge, people here and elsewhere have tended towards
> stiffer=stronger=better for most things having to do with wheels.
> Intuitively, I'd think that lateral stiffness would enhance cornering. But
> re-reading the paragraph in question-
>
> "As the number of spoke crossings increase the length of each spoke
> increases. Longer spokes are more flexible and contribute to decreased
> radial stiffness, which improves ride quality. Consequently wheels with
> more spoke crossings have lower lateral stiffness, which is important to
> cornering stability."
>
> - Perhaps I had it backward, and they're saying that lateral stiffness, not
> lower lateral stiffness, is a good thing?
>
> I have my own opinions, but I learn a lot more when I listen to what other
> people have to say about something than when I'm trying to defend myself.

lateral stiffness is better for [reducing] shimmy and leads to a more
"stable" feel. but it goes hand in hand with radial stiffness, and too
much of that can be uncomfortable for the rider.

>
> --Mike-- Chain Reaction Bicycles
> www.ChainReactionBicycles.com
>
>
>
> "jim beam" <[email protected]> wrote in message
> news:[email protected]...
>> Mike Jacoubowsky wrote:
>>> http://www.wheelbuilder.com/tips/Spokes.asp
>>> "As the number of spoke crossings increase the angle in which each spoke
>>> leaves the hub approaches 90o (tangential). Wheels with 3x or 4x lace
>>> patterns will usually transfer power more efficiently than those with 2x
>>> patterns. As the number of spoke crossings increase the length of each
>>> spoke increases. Longer spokes are more flexible and contribute to
>>> decreased radial stiffness, which improves ride quality. Consequently
>>> wheels with more spoke crossings have lower lateral stiffness, which is
>>> important to cornering stability."
>>>
>>> #1: Does a difference in spoke length from, say, 288mm to 302mm, which is
>>> about 5%, actually contribute to a difference you can feel?
>> you mean the difference between radial and tangential spoking? some
>> people say they can feel it. others not. does it matter?
>>
>>> #2: How does "lower lateral stiffness" improve cornering stability?
>> it doesn't actually say "it improves it", it says lateral stiffness is
>> important, but doesn't state the sense. lateral stiffness /can/ be
>> important if the rider jockeys or the frame is not very stiff torsionally
>> [shimmy], and stiffer is better.
>>
>> i guess your objective in this post is to illustrate misinformation and/or
>> ambiguity. if so, do you have a position on the subject or do you just
>> want to stir the pot?
>
>

 

[Ron Ruff]

jim beam wrote:
> lateral stiffness is better for [reducing] shimmy and leads to a more
> "stable" feel. but it goes hand in hand with radial stiffness, and too
> much of that can be uncomfortable for the rider.

On rear wheels at least, the lateral stiffness can be enhanced by
increasing the flange spacing... but then you need to go to a G3 style
lacing to get reasonable tension in the NDS spokes... but that is kinda
nice too, since now those spokes won't go slack from side loads...
*but* you don't have any better lateral stiffness than before. So I
guess I agree with you.

I must not be sensitive though... I can't tell the difference in radial
or lateral stiffness from one wheel to the next.

 

[Ron Ruff]

Mike Jacoubowsky wrote:
> - Perhaps I had it backward, and they're saying that lateral stiffness, not
> lower lateral stiffness, is a good thing?

I think they are saying that there is no free lunch... ie high lateral
stiffness is good for cornering, but bad for ride smoothness.
Personally, I think they are both insignificant effects. What you want
in a wheel is enough strength and durability so that the rim doesn't
taco and the spokes don't break. These qualities are weakly correlated
with stiffness. Maybe a wheel with poor lateral stiffness can induce
shimmy, but I've not experienced this.

 

[jim beam]

Ron Ruff wrote:
> jim beam wrote:
>> lateral stiffness is better for [reducing] shimmy and leads to a more
>> "stable" feel. but it goes hand in hand with radial stiffness, and too
>> much of that can be uncomfortable for the rider.
>
> On rear wheels at least, the lateral stiffness can be enhanced by
> increasing the flange spacing...

hard to do if you want to use a typical cassette hub. there's small
variations from maker to maker, but the max tension ratio difference
you'll get between them all is about 15%. using thicker drive side
spokes works though. stiffer rim does too.

> but then you need to go to a G3 style
> lacing to get reasonable tension in the NDS spokes...

tension does not affect elasticity.

> but that is kinda
> nice too, since now those spokes won't go slack from side loads...
> *but* you don't have any better lateral stiffness than before. So I
> guess I agree with you.
>
> I must not be sensitive though... I can't tell the difference in radial
> or lateral stiffness from one wheel to the next.
>

 

[jim beam]

Ron Ruff wrote:
> Mike Jacoubowsky wrote:
>> - Perhaps I had it backward, and they're saying that lateral stiffness, not
>> lower lateral stiffness, is a good thing?
>
> I think they are saying that there is no free lunch... ie high lateral
> stiffness is good for cornering, but bad for ride smoothness.
> Personally, I think they are both insignificant effects. What you want
> in a wheel is enough strength and durability so that the rim doesn't
> taco and the spokes don't break. These qualities are weakly correlated
> with stiffness. Maybe a wheel with poor lateral stiffness can induce
> shimmy, but I've not experienced this.
>
it doesn't induce it, but it's part of the shimmy equation. torsional
frame stiffness and [rear] wheel lateral stiffness both affect the
harmonic frequency of the shimmy. if both their frequencies coincide,
it's a real squirrelly ride.

 

[Ron Ruff]

jim beam wrote:
> tension does not affect elasticity.
Only when the spokes go slack...

 

[jim beam]

Ron Ruff wrote:
> jim beam wrote:
>> tension does not affect elasticity.
> Only when the spokes go slack...
>
ok...

 

[* * Chas]

"Mike Jacoubowsky" <[email protected]> wrote in message
news:[email protected]...
> http://www.wheelbuilder.com/tips/Spokes.asp
> "As the number of spoke crossings increase the angle in which each spoke
> leaves the hub approaches 90o (tangential). Wheels with 3x or 4x lace
> patterns will usually transfer power more efficiently than those with 2x
> patterns. As the number of spoke crossings increase the length of each
spoke
> increases. Longer spokes are more flexible and contribute to decreased
> radial stiffness, which improves ride quality. Consequently wheels with
> more spoke crossings have lower lateral stiffness, which is important to
> cornering stability."
>
> #1: Does a difference in spoke length from, say, 288mm to 302mm, which
is
> about 5%, actually contribute to a difference you can feel?
>
> #2: How does "lower lateral stiffness" improve cornering stability?
>
> --Mike-- Chain Reaction Bicycles
> www.ChainReactionBicycles.com
>

You opened a can of worms. I've preferred 4x cross low flange for years
because they are slightly "softer" riding. I have several identical wheel
set the only difference is 3x Vs 4x. I can definitely tell the difference.

The difference between 288mm to 302mm is 14mm which times 2 for each side
of the wheel is 28mm which is almost 1 1/8" in spoke length. Longer spokes
are going to make a slightly more flexible wheel.

The experts will start quoting all of their engineering formulas which
mostly apply to static rather than dynamic conditions. A there are so many
variables that a bicycle wheel in use can be better compared to fluid
dynamics.

The only time I've felt any lateral stiffness issues has been on very fast
descents on high mountain roads with wide sweeping bends at speeds over 40
mph.

Chas.

 

[* * Chas]

"Mike Jacoubowsky" <[email protected]> wrote in message
news:[email protected]...
> >> #2: How does "lower lateral stiffness" improve cornering stability?
> >
> > it doesn't actually say "it improves it", it says lateral stiffness is
> > important, but doesn't state the sense. lateral stiffness /can/ be
> > important if the rider jockeys or the frame is not very stiff
torsionally
> > [shimmy], and stiffer is better.
> >
> > i guess your objective in this post is to illustrate misinformation
and/or
> > ambiguity. if so, do you have a position on the subject or do you
just
> > want to stir the pot?
>
> No, my objective was to find out what people thought about the idea that
> too-much lateral stiffness is a bad thing. This is a new one to me. To
the
> best of my knowledge, people here and elsewhere have tended towards
> stiffer=stronger=better for most things having to do with wheels.
> Intuitively, I'd think that lateral stiffness would enhance cornering.
But
> re-reading the paragraph in question-
>
> "As the number of spoke crossings increase the length of each spoke
> increases. Longer spokes are more flexible and contribute to decreased
> radial stiffness, which improves ride quality. Consequently wheels with
> more spoke crossings have lower lateral stiffness, which is important to
> cornering stability."
>
> - Perhaps I had it backward, and they're saying that lateral stiffness,
not
> lower lateral stiffness, is a good thing?
>
> I have my own opinions, but I learn a lot more when I listen to what
other
> people have to say about something than when I'm trying to defend
myself.
>
> --Mike-- Chain Reaction Bicycles
> www.ChainReactionBicycles.com
>

Interesting approach. My preference is for smooth riding bikes that absorb
road shock and vibration. I'm not making any suggestions for others just
reporting my experiences. I enjoy riding old steel retro bikes.

I like a bike with a frame that is laterally stiff across the bottom
bracket and rear triangle areas so that when I'm honking out of the saddle
the chain doesn't rub back and forth on the front derailleur and in worst
cases of too much flex the gears shift by themselves.

I've found that light gage rear spokes whether 3x or 4x feel laterally
flexible when honking.

I recently rode a friend's LeMond with 2x 24 spoke wheels. The rear end
had a really responsive light, crisp feel that I've only ever felt on one
other bike over the years. My friend doesn't like the ride of most of my
bikes. He says that they feel too spongy.

OT - This brings up the old discussion: a stiff bike is better because it
more efficiently transfers the rider's energy Vs. a more comfortable bike
is more efficient because its easier on the rider.

I like my short wheelbase bikes for rides up to 40 miles or so because
they are more responsive. My old long wheelbase bikes are more comfortable
for longer rides.

Chas.

 

[* * Chas]

"jim beam" <[email protected]> wrote in message
news:[email protected]...
> Ron Ruff wrote:
> > Mike Jacoubowsky wrote:
> >> - Perhaps I had it backward, and they're saying that lateral
stiffness, not
> >> lower lateral stiffness, is a good thing?
> >
> > I think they are saying that there is no free lunch... ie high lateral
> > stiffness is good for cornering, but bad for ride smoothness.
> > Personally, I think they are both insignificant effects. What you want
> > in a wheel is enough strength and durability so that the rim doesn't
> > taco and the spokes don't break. These qualities are weakly correlated
> > with stiffness. Maybe a wheel with poor lateral stiffness can induce
> > shimmy, but I've not experienced this.
> >
> it doesn't induce it, but it's part of the shimmy equation. torsional
> frame stiffness and [rear] wheel lateral stiffness both affect the
> harmonic frequency of the shimmy. if both their frequencies coincide,
> it's a real squirrelly ride.

I haven't seen many shimmy problems recently but years ago found a
correlation between really long stems (130mm - 140mm) and front end shimmy
on long fast descents.

Changing to a shorter stem usually fixed the problem for many riders. At
that time fork and frame alignment weren't checked out very often. After I
built a few frames, I started checking alignment on any bike that felt
squirrelly.

In 1978 a customer brought in a brand new Bob Jackson bike that he got
from a MO house. It wanted to ride in circles to the right. I could
visually see the rear triangle was tweaked. One chainstay was 1/2" shorter
than the other and the rest of the frame including the forks were badly
aligned - the paint job was beautiful though.

I wonder if people with shimmy problems ever check their frame alignment.

Chas.

 

[Peter Cole]

jim beam wrote:

> lateral stiffness is better for [reducing] shimmy and leads to a more
> "stable" feel. but it goes hand in hand with radial stiffness, and too
> much of that can be uncomfortable for the rider.

The FEA in Jobst's book shows a nominal 0.15mm radial deflection with a
nominal 50kg load. What's your number for "uncomfortable"?

 

[Peter Cole]

Mike Jacoubowsky wrote:
> http://www.wheelbuilder.com/tips/Spokes.asp
> "As the number of spoke crossings increase the angle in which each spoke
> leaves the hub approaches 90o (tangential). Wheels with 3x or 4x lace
> patterns will usually transfer power more efficiently than those with 2x
> patterns. As the number of spoke crossings increase the length of each spoke
> increases. Longer spokes are more flexible and contribute to decreased
> radial stiffness, which improves ride quality. Consequently wheels with
> more spoke crossings have lower lateral stiffness, which is important to
> cornering stability."
>
> #1: Does a difference in spoke length from, say, 288mm to 302mm, which is
> about 5%, actually contribute to a difference you can feel?
>
> #2: How does "lower lateral stiffness" improve cornering stability?
>
> --Mike-- Chain Reaction Bicycles
> www.ChainReactionBicycles.com
>
>
>

I think they're trying to invent a trade-off between "comfort" and
"performance" -- adds a certain "cachet" to the wheel selection process,
but unfortunately it's all BS -- creative marketing for a 100 year old
product.