Flexy wheels (again)



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M

Mike S.

Guest
From www.sheldonbrown.com/rinard/wheel/index.htm

7.. How does spoke gauge affect stiffness? Thicker spokes make a wheel stiffer, if all else is
equal. A typical 32 spoke wheel built with 2.0mm spokes is about 11% stiffer than a similar wheel
built with 2.0-1.45mm swaged spokes.

Compare the deflection of two wheels: numbers 39 and 47. Wheel 39 is built with 2.0-1.45mm swaged
spokes, but wheel 47 is built with 2.0mm straight gauge spokes. Hub dimensions are effectively
identical, spoke count is the same and the rims are the same make and model, so the only
structural difference is the spoke gauge.

Result? The wheel with thinner spokes deflected 0.051" (1.30mm) in font and 0.067"1.70mm) in
the rear, but the wheel with thicker spokes deflected less: only 0.046" (1.17mm) and 0.055"
(1.40mm) for front and rear, respectively. That's an 11% increase in stiffness for the thicker
spoked wheels.

Interestingly, wheel stiffness depends on more than just spoke thickness; the rim and other
factors also contribute, so only part of the increase in raw spoke stiffness shows up in
measured wheel stiffness. The thicker spoke by itself is nearly twice as stiff axially as the
thinner spoke!

Since y'all are fond of making fun of me 'cause I can tell my wheel with the 15/16 spokes was
flexy, I thought I'd share this. I figure if Damon Rinard says so, it must be true!

Mike
 
J

Jon Isaacs

Guest
> Since y'all are fond of making fun of me 'cause I can tell my wheel with the 15/16 spokes was
> flexy, I thought I'd share this. I figure if Damon Rinard says so, it must be true!

Did you happen to notice the loads that Damon was applying? And then consider how large 0.051"
actually is?

Then did you wonder how you could apply a 50 lb side load to a wheel and whether 0.051" is a large
deflection?

Just curious.

Jon Isaacs
 
J

Jobst Brandt

Guest
Mike Shaw writes:

> Compare the deflection of two wheels: numbers 39 and 47. Wheel 39 is built with 2.0-1.45mm swaged
> spokes, but wheel 47 is built with
> 2.mm straight gauge spokes. Hub dimensions are effectively identical, spoke count is the same and
> the rims are the same make and model, so the only structural difference is the spoke gauge.

> Result? The wheel with thinner spokes deflected 0.051" (1.30mm) in font and 0.067"1.70mm) in
> the rear, but the wheel with thicker spokes deflected less: only 0.046" (1.17mm) and 0.055"
> (1.40mm) for front and rear, respectively. That's an 11% increase in stiffness for the thicker
> spoked wheels.

Maybe you can define what you mean by these numbers. They certainly have little to do with road
shock absorption because radial deflection of a wheel is about 1/10 of the values you list. Just the
same, how do you feel these minuscule differences you list? Unless you can explain the method of
differentiating between wheels whose deflection vary a couple of Xerox paper thicknesses, you won't
improve your credibility.

> Interestingly, wheel stiffness depends on more than just spoke thickness; the rim and other
> factors also contribute, so only part of the increase in raw spoke stiffness shows up in
> measured wheel stiffness. The thicker spoke by itself is nearly twice as stiff axially as the
> thinner spoke!

I think that is well understood among people who need to know.

> Since y'all are fond of making fun of me 'cause I can tell my wheel with the 15/16 spokes was
> flexy, I thought I'd share this. I figure if Damon Rinard says so, it must be true!

More bluntly, you are fooling yourself if you believe you can feel these deflections, aka you are
making a fool of yourself.

Jobst Brandt [email protected] Palo Alto CA
 
M

Mike S.

Guest
<[email protected]> wrote in message news:[email protected]...
> Mike Shaw writes:
>
> > Compare the deflection of two wheels: numbers 39 and 47. Wheel 39 is built with 2.0-1.45mm
> > swaged spokes, but wheel 47 is built with
> > 2.mm straight gauge spokes. Hub dimensions are effectively identical, spoke count is the same
> > and the rims are the same make and model, so the only structural difference is the spoke
> > gauge.
>
> > Result? The wheel with thinner spokes deflected 0.051" (1.30mm) in font and 0.067"1.70mm) in the
> > rear, but the wheel with thicker spokes deflected less: only 0.046" (1.17mm) and 0.055" (1.40mm)
> > for front and rear, respectively. That's an 11% increase in stiffness for the thicker spoked
> > wheels.
>
> Maybe you can define what you mean by these numbers. They certainly have little to do with road
> shock absorption because radial deflection of a wheel is about 1/10 of the values you list. Just
> the same, how do you feel these minuscule differences you list? Unless you can explain the method
> of differentiating between wheels whose deflection vary a couple of Xerox paper thicknesses, you
> won't improve your credibility.
>
> > Interestingly, wheel stiffness depends on more than just spoke thickness; the rim and other
> > factors also contribute, so only part of the increase in raw spoke stiffness shows up in
> > measured wheel stiffness. The thicker spoke by itself is nearly twice as stiff axially as the
> > thinner spoke!
>
> I think that is well understood among people who need to know.
>
> > Since y'all are fond of making fun of me 'cause I can tell my wheel with the 15/16 spokes was
> > flexy, I thought I'd share this. I figure if Damon Rinard says so, it must be true!
>
> More bluntly, you are fooling yourself if you believe you can feel these deflections, aka you are
> making a fool of yourself.
>
The test that Damon ran hung a weight off the side of the rim, testing lateral rigidity. I never
once said I noticed anything when I was JRA, only when sprinting, or diving into a corner. Since
sprinting and diving into a corner (at least the way I do it) produce lots of lateral loading, my
wheels flexed.

Y'all like data, I give you data. "Your" assumptions are faulty. "You" might want to recheck them.
Run tests like Damon did, proving that wheels deflect laterally as well as vertically, then rethink
"your" position on what I'm saying about a flexy wheel.

Mike

> Jobst Brandt [email protected] Palo Alto CA
 
J

Jobst Brandt

Guest
Mike Shaw writes:

>>> Since y'all are fond of making fun of me 'cause I can tell my wheel with the 15/16 spokes was
>>> flexy, I thought I'd share this. I figure if Damon Rinard says so, it must be true!

>> More bluntly, you are fooling yourself if you believe you can feel these deflections, aka you are
>> making a fool of yourself.

> The test that Damon ran hung a weight off the side of the rim, testing lateral rigidity.

I wasn't interested in those tests, tests that were repeated from "the Bicycle Wheels" where all
this was explained and reported in conjunction with tying and soldering spoke crossings for "more
stiffness" that was not achieved.

> I never once said I noticed anything when I was JRA, only when sprinting, or diving into a corner.
> Since sprinting and diving into a corner (at least the way I do it) produce lots of lateral
> loading, my wheels flexed.

I was interested in your ability to detect deflections of less than a millimeter while riding your
bicycle. Although you may think you are placing side loads on your wheels, they are insignificantly
small and would not cause the side forces used in tests to cause imperceptible, although measurable,
lateral deflections.

> Y'all like data, I give you data.

I see no data for your contentions.

> "Your" assumptions are faulty. "You" might want to recheck them. Run tests like Damon did, proving
> that wheels deflect laterally as well as vertically, then rethink "your" position on what I'm
> saying about a flexy wheel.

I'm sorry. My measurements were the ones that got Damon to repeat and verify them as well as other
tests such as tire clinch and tire retention on rims.

Jobst Brandt [email protected] Palo Alto CA
 
M

Mike S.

Guest
<[email protected]> wrote in message news:[email protected]...
> Mike Shaw writes:
>
> >>> Since y'all are fond of making fun of me 'cause I can tell my wheel with the 15/16 spokes was
> >>> flexy, I thought I'd share this. I figure if Damon Rinard says so, it must be true!
>
> >> More bluntly, you are fooling yourself if you believe you can feel these deflections, aka you
> >> are making a fool of yourself.
>
> > The test that Damon ran hung a weight off the side of the rim, testing lateral rigidity.
>
> I wasn't interested in those tests, tests that were repeated from "the Bicycle Wheels" where all
> this was explained and reported in conjunction with tying and soldering spoke crossings for "more
> stiffness" that was not achieved.
>
> > I never once said I noticed anything when I was JRA, only when sprinting, or diving into a
> > corner. Since sprinting and diving into a corner (at least the way I do it) produce lots of
> > lateral loading, my wheels flexed.
>
> I was interested in your ability to detect deflections of less than a millimeter while riding your
> bicycle. Although you may think you are placing side loads on your wheels, they are
> insignificantly small and would not cause the side forces used in tests to cause imperceptible,
> although measurable, lateral deflections.
>

According to Damon's data, the deflection for a wheel similar to mine was
1.7mm, you don't think that that's not noticeable? If a deflection laterally of almost 2mm isn't
noticeable, what is??

> > Y'all like data, I give you data.
>
> I see no data for your contentions.
>
> > "Your" assumptions are faulty. "You" might want to recheck them. Run tests like Damon did,
> > proving that wheels deflect laterally as well as vertically, then rethink "your" position on
> > what I'm saying about a flexy wheel.
>
> I'm sorry. My measurements were the ones that got Damon to repeat and verify them as well as other
> tests such as tire clinch and tire retention on rims.

helped inspire, wheels flexed laterally from a min of a little over 1mm to a max of over 5mm. That's
not noticeable?

Go back to your ivory tower and run some more irrelevent tests, I'm going to go do some
more training.

Mike
>
> Jobst Brandt [email protected] Palo Alto CA
 
P

Paul Hays

Guest
On Mon, 17 Mar 2003 11:33:22 -0800, Mike S. wrote (in message <[email protected]>):

> According to Damon's data, the deflection for a wheel similar to mine was
> 1.7mm, you don't think that that's not noticeable? If a deflection laterally of almost 2mm isn't
> noticeable, what is??

Exactly. I think the problem is that most people would argue that a deflection of 1.7mm (~1/16th
inch) is, in fact, *not* noticeable while riding the bike, that such a small deflection would be
lost within the overall noise in the system.

You must be a true prince! ;)
http://childhoodreading.com/Edmund_Dulac_and_Gus/Princess_and_the_Pea.html
 
E

Eric Holeman

Guest
In article <[email protected]>,
Mike S. <[email protected]> wrote:

>According to Damon's data, the deflection for a wheel similar to mine was
>1.7mm, you don't think that that's not noticeable?

The only way to test if something is "noticeable" is to do a blind test. This is easy enough to do
with wheels.

>Go back to your ivory tower and run some more irrelevent tests, I'm going to go do some more
>training.

There you go again.

--
---
Eric Holeman Chicago Illinois USA
 
T

Tim McNamara

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

> The test that Damon ran hung a weight off the side of the rim, testing lateral rigidity. I never
> once said I noticed anything when I was JRA, only when sprinting, or diving into a corner. Since
> sprinting and diving into a corner (at least the way I do it) produce lots of lateral loading, my
> wheels flexed.

You seem to be conceptualizing turning a bike to be like turning a car, with large side loads on
the wheels/tires. Do you lean your bike over in corners? What do you think happens to the forces
when you do?

-----------------------> Lateral (centripital) forces \
| \ \ \ < Lean angle \ \ \ \ \
------------------------- Ground

The dashed vertical line is gravity. When you lean into the corner, from the perspective of your
wheels the forces are still vertical. The faster you go, the more you lean and the wheel still
thinks the forces are vertical. There's very little side loading when you corner a bike- unlike the
side loads a car wheel sees because the car wheel remains nearly upright throughout the turn.

> Y'all like data, I give you data. "Your" assumptions are faulty. "You" might want to recheck them.
> Run tests like Damon did, proving that wheels deflect laterally as well as vertically, then
> rethink "your" position on what I'm saying about a flexy wheel.

Hummm, how big are the lateral deflections again? 5 hundreths of an inch or something like that? Do
you really think you can feel such small movements- about the thickness of a couple of dollar bills-
even if they did happen while riding? And vertical deflection is yet another decimal place smaller
than Rinard's measured side deflections!

You're dreaming if you think these are significant. But carry on, it keeps the bike industry in
business. New for 2004 will be the Mavic "Atlas" wheel with RLD (Reduced Lateral Deflection) using
LTRD (Laterally Tuned Radial Differential) spokes to go along with the existing CD, Maxtal, SUP,
UBC, Ceramic2 plasma torch welded semiconductive unobtanium patented technologies. VeloNews will be
happy to let you know just how good these wheels are and you'll never lose another bike race again.
You heard it here first. Good luck!
 
A

Andy Coggan

Guest
"Mike S." <[email protected]> wrote in message news:[email protected]...
>
> <[email protected]> wrote in message news:[email protected]...
> > Mike Shaw writes:
> >
> > >>> Since y'all are fond of making fun of me 'cause I can tell my wheel with the 15/16 spokes
> > >>> was flexy, I thought I'd share this. I figure if Damon Rinard says so, it must be true!
> >
> > >> More bluntly, you are fooling yourself if you believe you can feel these deflections, aka you
> > >> are making a fool of yourself.
> >
> > > The test that Damon ran hung a weight off the side of the rim, testing lateral rigidity.
> >
> > I wasn't interested in those tests, tests that were repeated from "the Bicycle Wheels" where all
> > this was explained and reported in conjunction with tying and soldering spoke crossings for
> > "more stiffness" that was not achieved.
> >
> > > I never once said I noticed anything when I was JRA, only when sprinting, or diving into a
> > > corner. Since sprinting and diving into a corner (at least the way I do it) produce lots of
> > > lateral loading, my wheels flexed.
> >
> > I was interested in your ability to detect deflections of less than a millimeter while riding
> > your bicycle. Although you may think you are placing side loads on your wheels, they are
> > insignificantly small and would not cause the side forces used in tests to cause imperceptible,
> > although measurable, lateral deflections.
> >
>
> According to Damon's data, the deflection for a wheel similar to mine was
> 1.7mm, you don't think that that's not noticeable? If a deflection laterally of almost 2mm isn't
> noticeable, what is??
>
>
> > > Y'all like data, I give you data.
> >
> > I see no data for your contentions.
> >
> > > "Your" assumptions are faulty. "You" might want to recheck them. Run tests like Damon did,
> > > proving that wheels deflect laterally as well as vertically, then rethink "your" position on
> > > what I'm saying about a flexy wheel.
> >
> > I'm sorry. My measurements were the ones that got Damon to repeat and verify them as well as
> > other tests such as tire clinch and tire retention on rims.
>

you
> helped inspire, wheels flexed laterally from a min of a little over 1mm to
a
> max of over 5mm. That's not noticeable?

wheel, not matter how hard you dive into a corner or rock the bike from side to side when sprinting.

> Go back to your ivory tower and run some more irrelevent tests, I'm going
to
> go do some more training.

Ah, I get it: now that the data have been shown to not support your conclusions, they are suddenly
irrelevant ivory tower tests.

Andy Coggan
 
M

Mike S.

Guest
"Tim McNamara" <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>, "Mike S." <[email protected]> wrote:
>
> > The test that Damon ran hung a weight off the side of the rim, testing lateral rigidity. I never
> > once said I noticed anything when I was JRA,
only
> > when sprinting, or diving into a corner. Since sprinting and diving
into a
> > corner (at least the way I do it) produce lots of lateral loading, my
wheels
> > flexed.
>
> You seem to be conceptualizing turning a bike to be like turning a car, with large side loads on
> the wheels/tires. Do you lean your bike over in corners? What do you think happens to the forces
> when you do?
>
> -----------------------> Lateral (centripital) forces \
> | \ \ \ < Lean angle \ \ \ \ \
> ------------------------- Ground
>
> The dashed vertical line is gravity. When you lean into the corner, from the perspective of your
> wheels the forces are still vertical. The faster you go, the more you lean and the wheel still
> thinks the forces are vertical. There's very little side loading when you corner a bike- unlike
> the side loads a car wheel sees because the car wheel remains nearly upright throughout the turn.
>

That would be true given a perfectly smooth surface, and we all know that roads are not perfectly
smooth. Irregularities magnify flex by adding to the side loads. Since Damon's test didn't include
impacts, but a smooth application of weight, neither of us know what maximum flex for my wheels are,
now do we?

> > Y'all like data, I give you data. "Your" assumptions are faulty. "You" might want to recheck
> > them. Run tests like Damon did, proving that wheels deflect laterally as well as vertically,
> > then rethink "your" position on what I'm saying about a flexy wheel.
>
> Hummm, how big are the lateral deflections again? 5 hundreths of an inch or something like that?

Try 1.7mm thank you. On top of the tire squirm, that's noticeable. It wouldn't have been an issue if
all I were doing is toodling around like some people here, but since I'm doing sprints, etc. the
flex is magnified.

Do you really think you can feel such
> small movements- about the thickness of a couple of dollar bills- even if they did happen
> while riding?

Roll up the dollar bills into a 1.7mm stack and run over them going around a corner and tell me if
you don't feel it. Hell, run over a pebble next time you're out and tell me you don't feel it. (just
for a fair comparison, ride your 700x23c tires at 110-115psi like I do)

And vertical deflection is yet
> another decimal place smaller than Rinard's measured side deflections!
>
I never said that the wheel felt any different when JRA, only when sprinting or hard cornering.

New for 2004 will be the Mavic
> "Atlas" wheel with RLD (Reduced Lateral Deflection) using LTRD (Laterally Tuned Radial
> Differential) spokes to go along with the existing CD, Maxtal, SUP, UBC, Ceramic2 plasma torch
> welded semiconductive unobtanium patented technologies. VeloNews will be happy to let you know
> just how good these wheels are and you'll never lose another bike race again. You heard it here
> first. Good luck!
 
M

Mike S.

Guest
"Andy Coggan" <[email protected]> wrote in message
news:[email protected]...
> "Mike S." <[email protected]> wrote in message news:[email protected]...
> >
> > <[email protected]> wrote in message
> > news:[email protected]...
> > > Mike Shaw writes:
> > >
> > > >>> Since y'all are fond of making fun of me 'cause I can tell my wheel with the 15/16 spokes
> > > >>> was flexy, I thought I'd share this. I figure if Damon Rinard says so, it must be true!
> > >
> > > >> More bluntly, you are fooling yourself if you believe you can feel these deflections, aka
> > > >> you are making a fool of yourself.
> > >
> > > > The test that Damon ran hung a weight off the side of the rim, testing lateral rigidity.
> > >
> > > I wasn't interested in those tests, tests that were repeated from "the Bicycle Wheels" where
> > > all this was explained and reported in conjunction with tying and soldering spoke crossings
> > > for "more stiffness" that was not achieved.
> > >
> > > > I never once said I noticed anything when I was JRA, only when sprinting, or diving into a
> > > > corner. Since sprinting and diving into a corner (at least the way I do it) produce lots of
> > > > lateral loading, my wheels flexed.
> > >
> > > I was interested in your ability to detect deflections of less than a millimeter while riding
> > > your bicycle. Although you may think you are placing side loads on your wheels, they are
> > > insignificantly small and would not cause the side forces used in tests to cause
> > > imperceptible, although measurable, lateral deflections.
> > >
> >
> > According to Damon's data, the deflection for a wheel similar to mine
was
> > 1.7mm, you don't think that that's not noticeable? If a deflection laterally of almost 2mm isn't
> > noticeable, what is??
> >
> >
> > > > Y'all like data, I give you data.
> > >
> > > I see no data for your contentions.
> > >
> > > > "Your" assumptions are faulty. "You" might want to recheck them. Run tests like Damon did,
> > > > proving that wheels deflect laterally as well as vertically, then rethink "your" position on
> > > > what I'm saying about a flexy wheel.
> > >
> > > I'm sorry. My measurements were the ones that got Damon to repeat and verify them as well as
> > > other tests such as tire clinch and tire retention on rims.
> >

> you
> > helped inspire, wheels flexed laterally from a min of a little over 1mm
to
> a
> > max of over 5mm. That's not noticeable?
>

> wheel, not matter how hard you dive into a corner or rock the bike from
side
> to side when sprinting.

Between my 180# and sprinting technique, I'd be willing to bet that I can.

>
> > Go back to your ivory tower and run some more irrelevent tests, I'm
going
> to
> > go do some more training.
>
> Ah, I get it: now that the data have been shown to not support your conclusions, they are suddenly
> irrelevant ivory tower tests.
>
> Andy Coggan
>
>
Actually, the data does support my theory that there is flex laterally in a wheel similar to mine.
The problem is that noone seems to have experienced it for themselves, so they don't believe me.

Here's a challenge for those of you that weigh about 180#. Go build a front wheel with 32 15/16
spokes, using an Open Pro/Reflex rim, and go sprint on
it. Then tell me that there's no flex in the front wheel. Make sure that you go all out, I
wouldn't want anyone to half-ass it and not get the full experience. I'm tempted to build
another one myself and have Jon come over and ride the wheel and let me know what he feels. My
guess is that the wheel will feel exactly like a wheel JRA, and flex laterally when he's
sprinting on it.

Mike
 
T

Toby Hamilton

Guest
"Mike S." wrote:

> Here's a challenge for those of you that weigh about 180#. Go build a
front
> wheel with 32 15/16 spokes, using an Open Pro/Reflex rim, and go sprint on
> it. Then tell me that there's no flex in the front wheel. Make sure that you go all out, I
> wouldn't want anyone to half-ass it and not get the full experience.

Well that's pretty close to what I have, except 36 spokes instead of 32. But then I weigh about 240
lbs, so maybe that makes up for the extra four spokes. I've never noticed any flex in my front
wheel, even when I sprinted all out against a couple of teenagers who wanted to race.

--
Toby Hamilton ([email protected])
 
K

Kraig Willett

Guest
From the looks of this thread, there appears to be some history that I am unaware of.

At the risk of getting in the middle of something, I would like to comment that I have measured
between the pad deflections dynamically - that is I slapped a dial indicator on my bike and rode it
around while noting maximum deflections (which occurred while out of the saddle - cornering
deflections were minimal).

I also measured the static deflections for the same wheels. With these two data sets it was possible
to back out the lateral loads. I found that lean angle did not account for all the deflection that I
was measuring. Where did the rest come from?

Anyway, I put together a quick page (5 minutes of cutting and pasting, believe me, you'll agree) at:

http://tinyurl.com/7o9q

to show the setup and some of the raw data.

This analysis was part of a wheel review I wrote, which can be seen at:

http://tinyurl.com/6424

I welcome your comments on my lame (though pretty reliable and correlates well with Rinard's)
test setup.

The discussion of perception is interesting and I could tell you some good stories from my days as a
wheel development engineer - but I won't bore you with those details - there are plenty of people
here more experienced and clever than I.

--
==================
Kraig Willett www.biketechreview.com
==================
 
J

Jobst Brandt

Guest
Mike Shaw writes:

>>>>> Since y'all are fond of making fun of me 'cause I can tell my wheel with the 15/16 spokes was
>>>>> flexy, I thought I'd share this. I figure if Damon Rinard says so, it must be true!

>>>> More bluntly, you are fooling yourself if you believe you can feel these deflections, aka you
>>>> are making a fool of yourself.

>>> The test that Damon ran hung a weight off the side of the rim, testing lateral rigidity.

>> I wasn't interested in those tests, tests that were repeated from "the Bicycle Wheels" where all
>> this was explained and reported in conjunction with tying and soldering spoke crossings for "more
>> stiffness" that was not achieved.

>>> I never once said I noticed anything when I was JRA, only when sprinting, or diving into a
>>> corner. Since sprinting and diving into a corner (at least the way I do it) produce lots of
>>> lateral loading, my wheels flexed.

>> I was interested in your ability to detect deflections of less than a millimeter while riding
>> your bicycle. Although you may think you are placing side loads on your wheels, they are
>> insignificantly small and would not cause the side forces used in tests to cause imperceptible,
>> although measurable, lateral deflections.

> According to Damon's data, the deflection for a wheel similar to mine was 1.7mm, you don't think
> that that's not noticeable? If a deflection laterally of almost 2mm isn't noticeable, what is??

Ah, yes but the difference between this wheel and more rigid ones is less than a millimeter and this
is at loads that you cannot generate while riding.

>>> Y'all like data, I give you data.

>> I see no data for your contentions.

>>> "Your" assumptions are faulty. "You" might want to recheck them. Run tests like Damon did,
>>> proving that wheels deflect laterally as well as vertically, then rethink "your" position on
>>> what I'm saying about a flexy wheel.

>> I'm sorry. My measurements were the ones that got Damon to repeat and verify them as well as
>> other tests such as tire clinch and tire retention on rims.

> ostensibly you helped inspire, wheels flexed laterally from a min of a little over 1mm to a max of
> over 5mm. That's not noticeable?

I'm sorry that you can't control your emotions in this discussion and keep a civil tone. Dragging in
wheels with 5mm deflection, wheels that you don't ride, is specious argumentation. Just the same,
leaning into curves does not cause such side loads. The reason for these test loads is to generate
sufficiently large deflections to characterize elasticity of different wheels within their elastic
limits. It is not that such loads occur while riding.

> Go back to your ivory tower and run some more irrelevent tests, I'm going to go do some more
> training.

You seem to take all this so personally, as though you had some ax to grind with academia?

Jobst Brandt [email protected] Palo Alto CA
 
T

Tim McNamara

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

> "Tim McNamara" <[email protected]> wrote in message
> news:[email protected]...
> > In article <[email protected]>, "Mike S." <[email protected]> wrote:
> >
> > > The test that Damon ran hung a weight off the side of the rim, testing lateral rigidity. I
> > > never once said I noticed anything when I was JRA, only when sprinting, or diving into a
> > > corner. Since sprinting and diving into a corner (at least the way I do
> > > it) produce lots of lateral loading, my wheels flexed.
> >
> > You seem to be conceptualizing turning a bike to be like turning a car, with large side loads on
> > the wheels/tires. Do you lean your bike over in corners? What do you think happens to the forces
> > when you do?
> >
> > -----------------------> Lateral (centripital) forces
> > | \ \ \ < Lean angle \ \ \ \ \
> > ------------------------- Ground
> >
> > The dashed vertical line is gravity. When you lean into the corner, from the perspective of
> > your wheels the forces are still vertical. The faster you go, the more you lean and the wheel
> > still thinks the forces are vertical. There's very little side loading when you corner a bike-
> > unlike the side loads a car wheel sees because the car wheel remains nearly upright throughout
> > the turn.
> >
>
> That would be true given a perfectly smooth surface, and we all know that roads are not perfectly
> smooth. Irregularities magnify flex by adding to the side loads. Since Damon's test didn't include
> impacts, but a smooth application of weight, neither of us know what maximum flex for my wheels
> are, now do we?

How big an irregularity are you talking about? Six inch potholes? You're still not going to add
significant side loads hitting some typical road bumps- the wheels will still mostly see them as
vertical loads. If the side loading is enough to be significant, it will lift the wheel and you will
crash, unless you're riding at parking lot speeds.

> > > Y'all like data, I give you data. "Your" assumptions are faulty. "You" might want to recheck
> > > them. Run tests like Damon did, proving that wheels deflect laterally as well as vertically,
> > > then rethink "your" position on what I'm saying about a flexy wheel.
> >
> > Hummm, how big are the lateral deflections again? 5 hundreths of an inch or something like that?
>
> Try 1.7mm thank you. On top of the tire squirm, that's noticeable. It wouldn't have been an issue
> if all I were doing is toodling around like some people here, but since I'm doing sprints, etc.
> the flex is magnified.

Ah, Now I see. You can feel a 0.05" flex masked through the tire squirm, while you're cornering hard
and therefore paying more attanetion to the road than your bike, and you can differentiate this from
frame flex, fork flex, handlebar flex, and stem flex.

You're right, we do like to make fun of stupid stuff like this. You also seem to be oblivious to the
fact that most of the people in this newsgroup ride hard and have ridden hard for years- 30 years or
more for several of us, myself included. Many of us have raced- myself included, for 10 years.

> > Do you really think you can feel such small movements- about the thickness of a couple of dollar
> > bills- even if they did happen while riding?
>
> Roll up the dollar bills into a 1.7mm stack and run over them going around a corner and tell me if
> you don't feel it. Hell, run over a pebble next time you're out and tell me you don't feel it.
> (just for a fair comparison, ride your 700x23c tires at 110-115psi like I
> do)

I ride mine at 120 psi. At 200+ lbs, pinch flats are a problem with silly small tires like that.
Could I feel a 1.7 mm bump, on 700 x 23's at 120 psi? Possibly. But that's an acute event with a
definable edge, and might impart enough kinetic energy to cross the threshold of perceptibility.
It's the edge effect you perceive. Wheel flex is a non-acute event without a definable edge; you're
simply not going to be able to feel it at such small magnitudes. And certainly not with all the
other competing stimulus.

Whatever you're feeling in corners, it's something other than what you think it is. That's all
we're saying- your perception may or may not be accurate, but your explanation is highly unlikely
to be accurate.

> > And vertical deflection is yet another decimal place smaller than Rinard's measured side
> > deflections!
> >
> I never said that the wheel felt any different when JRA, only when sprinting or hard cornering.

Yes, you are obviously going so fast that the laws of physics and the laws of perception are in
abeyance. I should have realized.

ROTFL!
 
M

Mike S.

Guest
"Kraig Willett" <[email protected]> wrote in message
news:[email protected]...
> From the looks of this thread, there appears to be some history that I am unaware of.
>
> At the risk of getting in the middle of something, I would like to comment that I have measured
> between the pad deflections dynamically - that is I slapped a dial indicator on my bike and rode
> it around while noting maximum deflections (which occurred while out of the saddle - cornering
> deflections were minimal).
>
All you're jumping in the middle of is me getting people's back up by stating that I disagree with
Jobst and the other resident engineers.

For a little background, I built a front 32 hole Ultegra/Open SUP CD/15/16 that I'm claiming are
flexy. At 180#, being a sprinter, I am saying that I felt the front wheel flex when sprinting or
cornering hard.

The resident engineers are saying that wheels don't flex, and even if they did, I couldn't feel it.

Other than a lot of people saying that I'm full of it (and vice versa), that's about the argument.

Mike

> I also measured the static deflections for the same wheels. With these two data sets it was
> possible to back out the lateral loads. I found that lean angle did not account for all the
> deflection that I was measuring. Where did the rest come from?
>
> Anyway, I put together a quick page (5 minutes of cutting and pasting, believe me, you'll
> agree) at:
>
> http://tinyurl.com/7o9q
>
> to show the setup and some of the raw data.
>
> This analysis was part of a wheel review I wrote, which can be seen at:
>
> http://tinyurl.com/6424
>
> I welcome your comments on my lame (though pretty reliable and correlates well with Rinard's)
> test setup.
>
> The discussion of perception is interesting and I could tell you some good stories from my days as
> a wheel development engineer - but I won't bore you with those details - there are plenty of
> people here more experienced and clever than I.
>
>
> --
> ==================
> Kraig Willett www.biketechreview.com
> ==================
 
S

Steve Blankensh

Guest
"Andy Coggan" <[email protected]> wrote in message
news:[email protected]...
> "Steve Blankenship" <[email protected]> wrote in message
> news:[email protected]...
>
> > But - I'll also cop to believing wheel flex can possibly be a problem,
but
> > for my scrawny butt, it took 28H-15/16-spoke GEL280's and fast, windy descents to initially
> > convert me.
>
> But wasn't Mike S's claim that it was spoke gauge, and not spoke count or rim stiffness, that
> accounted for the flex he thought he felt? To state it another way: now much of what you felt was
> due to the fact that you were using light rims combined with a lower-than-normal number of
> spokes, vs.
the
> fact that the spokes were 15/16 gauge?
>
> Andy Coggan
>

Heck, I won't even swear that stiffness WAS the issue; maybe it was the drastically lower wheel
inertia allowing small inputs to knock the bike off-line more, requiring compensating corrections
that were perceived as flex-induced. But seeing how easy it was to flex those spindly old GEL280's
laterally, it WAS what I always suspected, and have ever since favored more robust wheels. Those
things were OK in the flats, but were useless at 40mph+. A gust of wind would give you religion!

My take on Mike S's post is that he thought that he could feel a given wheel with very thin (1.45mm)
spokes flex more than an identical one with 2.0's. Having built and ridden a lot of wheels in 22
years of cycling, I'd agree that you can definitely feel the difference two such examples, and that
the wheel that IS stiffer will "feel" stiffer and more stable. Above a certain minimum threshold
(that will vary by rider), it's a non-issue in terms of control, of course. But regardless of
whether it's truly a direct function of lateral flex or some other mechanism, I'd say it correlates
well enough with lateral flex to support his contention for practical purposes.

As for people being able to perceive small amounts of flex, it reminds me a bit of the contention
among some PC gamers that you can't perceive screen updates above 30FPS. But no, we won't go
there... ;-)

SB
 
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