Opinions on aluminum frames?

[David L. Johnso]

On Wed, 19 Mar 2003 09:35:15 -0500, archer wrote:

> They don't all prefer the same one, but they can tell that there is a difference.

Because they put labels on them, telling you which is which.

> I haven't measured it, but if you are running 160 psi tires on a road in good condition,

Which is already over the top. that is a lot of pressure.

> your tires probably aren't deflecting more than a few thousandths of an inch in response to the
> normal texture of the road surface, especially if you are a relatively light rider.

I typically ride with more like 100lbs pressure, and though I would not qualify as light, am not
twice "light". So, my tires would flex probably less than four times the amount you suggest.
However, on normal roads my tires easily deflect 1/4", and if I lowered the pressure by much below
that the deflection would be serious enough to invite snake bite flats. So I think your assumption
here is off by an order of magnitude or more.

This amount of
> vertical compliance is in the same range as another poster said the frame deflects under load, so
> the statement that the tires have orders of magnitude more effect on the ride than the frame may
> be a bit of an exaggeration,

But I think the order of magnitude difference is right in your assumptions.

depending of course on the rider and tire. He also said
> that the deflection he measured ranged from .001 to .003. That may not seem like much difference,
> but that factor of three may well be significant in changing the amount of vibration transmitted
> to the rider.

Not when compared to a 0.1" deflection from the tire.

> One thing I haven't seen anybody mention is how the riding speed will affect the ride quality
> (meaning the amount of vibration and shock transmitted to the rider). There isn't much damping in
> the vertical direction on non-suspended bicycle, but there is some, and speed will affect the
> bike's response to road irregularities; it's called resonance, and the stiffness and damping
> characteristics have major effects on it. Just think of driving your car over a speed bump: there
> is always a "best" speed to hit it, where your car bounces the least. That is due to the spring
> rates and damping in the suspension, along with the weight of the car.

True, though that is not resonance. You are talking about the reponse of the system to an external
input that is something like a delta function, technically called an impulse.

--

David L. Johnson

__o | Accept risk. Accept responsibility. Put a lawyer out of _`\(,_ | business. (_)/ (_) |

 

[Frank Krygowski]

archer wrote:
>
>
> I haven't measured it, but if you are running 160 psi tires on a road in good condition, your
> tires probably aren't deflecting more than a few thousandths of an inch in response to the normal
> texture of the road surface, especially if you are a relatively light rider.

Why not measure the tire deflection? All it takes is a dial indicator. You can borrow one from a
mechanical engineer. ;-)

I'd do it for you, but I don't run 160 psi in my tires.

> He also said that the deflection he measured ranged from .001 to .003. That may not seem like much
> difference, but that factor of three may well be significant in changing the amount of vibration
> transmitted to the rider.

Yep. And the capacitance of the house wiring may change the voltage reaching my computer! I may be
able to feel the effects through my keyboard!

Ah, well.

--
Frank Krygowski [email protected]

 

[Frank Krygowski]

"Mike S." wrote:
>
> "Frank Krygowski" <[email protected]> wrote in message news:[email protected]..
> > You've got to learn the vocabulary to discuss this coherently!
> >
> I've been trying, but since I haven't had the experience of actually studying this stuff, I'm
> using terms that may be comfusing to those that actually know their definitions. Not that I
> haven't been picking things up, but hey, you try talking about say, financial planning without
> actually being a registered rep!

Here's the difference, Mike. If you were (or are?) a financial planner, and this were a long debate
about financial planning, I wouldn't be arguing with you. Why? Because I'm _not_ a financial
planner, and I know better than to make uneducated arguments against experts.

>
> > >
> > > If the downtube does not resist torsion, and the seattube does not
> resist
> > > lateral flex, we get a flexible bike, right?
> >
> > Right - out of plane, as I explained in another post.
>
> ...and I keep pointing out that out of plane flexibility is a part of the ride of a bike, but you
> don't believe me.

Don't say I don't believe you. Re-read my post where I described three aspects of what I consider
"ride" to be. Out-of-plane stiffness is one of them.

It's not that I don't believe you. It's that I don't know exactly what to believe, because for so
long, you have been unwilling (or unable) to define your terms!

>
> >
> > > The forces of riding a bike are all centered around the point of input of energy: the BB. Are
> > > we in agreement?
> >
> > Nope. That sentence has no meaning in a technical sense. The forces are applied to their
> > respective contact points at the frame. They are not "centered" anywhere.
> >
> >
> See above about being technical. All right, here goes: with every action there is an equal and
> opposite reaction, no? As you press on the pedals, where does that energy go? Through the crank,
> BB, into the frame through the BB. Worst case, you are standing on the pedals, and all of your
> weight goes straight down. Once the pedals are pushed on by your legs, your body is being forced
> up and back, some of the force goes sideways, lots goes down.
>
> We in agreement?

<sigh> No. If you push downward on the pedals, the force goes downward. Under the usual
circumstances, it's not true that "some of the force goes sideways."

Honestly, you still have no idea how far you are missing the basics. To begin with, what do you mean
by "sideways"? Are you talking about situations where the bike is essentially vertical, or are you
looking at some special case where a person is tilting the bike markedly side to side (say, while
climbing)? Are you perhaps confusing deflection with force, or assuming that if there is a
deflection, there must be a force in its direction?

>
> The harder you push down, the more you are rising off the saddle (or being pushed backwards), the
> more lateral force is being exerted through the BB area, and more goes straight down. The easier
> you spin, the less these forces are.
>
> Right? Feel free to insert the "proper" use of these terms if I'm not getting them exactly right
> if it helps you to understand what I'm trying to say.
>
> All right, I'm going to stop here and see if we're still together.

Honestly, I don't see how anything you said above is relevant. And it remains true that you are so
far from understanding the basics - that is, the definitions of force, torque, moment, energy,
stress, strain, elementary coordinate systems, the concept of a free body diagram, Newton's laws of
motion, material properties...

It's kind of like a jazz musician arguing derivative investments with a stockbroker, using analogy
to 12-tone music theory. Lots of big words, but little practical meaning.

--
Frank Krygowski [email protected]

 

[Mike S.]

"Frank Krygowski" <[email protected]> wrote in message news:[email protected]...
> "Mike S." wrote:
> >
> > "Frank Krygowski" <[email protected]> wrote in message news:[email protected]..
> > > You've got to learn the vocabulary to discuss this coherently!
> > >
> > I've been trying, but since I haven't had the experience of actually studying this stuff, I'm
> > using terms that may be comfusing to those that actually know their definitions. Not that I
> > haven't been picking things
up,
> > but hey, you try talking about say, financial planning without actually being a registered rep!
>
> Here's the difference, Mike. If you were (or are?) a financial planner, and this were a long
> debate about financial planning, I wouldn't be arguing with you. Why? Because I'm _not_ a
> financial planner, and I know better than to make uneducated arguments against experts.
>
I'm smart enough to know that what's being said around here doesn't conform to what I've
experienced, and just stupid enough to try and discuss it with "the experts." Engineering education
or not, you're not talking to some half-wit here... mis-informed maybe, using the wrong terms
interchangeably probably, wrong, doubt it, but can't get my ideas across so that they're understood.

But that's what you get when you actually try and think for yourself instead of relying on someone
else's assumptions.

Mike
> > > >
> > > > If the downtube does not resist torsion, and the seattube does not
> > resist
> > > > lateral flex, we get a flexible bike, right?
> > >
> > > Right - out of plane, as I explained in another post.
> >
> > ...and I keep pointing out that out of plane flexibility is a part of
the
> > ride of a bike, but you don't believe me.
>
> Don't say I don't believe you. Re-read my post where I described three aspects of what I consider
> "ride" to be. Out-of-plane stiffness is one of them.
>
> It's not that I don't believe you. It's that I don't know exactly what to believe, because for so
> long, you have been unwilling (or unable) to define your terms!
>
Unable, mostly. Like I said before, if I knew specifics, don't you think I'd have brought them
out by now?

Mike
>
>
> >
> > >
> > > > The forces of riding a bike are all centered around the point of input of energy: the BB.
> > > > Are
we in
> > > > agreement?
> > >
> > > Nope. That sentence has no meaning in a technical sense. The forces are applied to their
> > > respective contact points at the frame. They are not "centered" anywhere.
> > >
> > >
> > See above about being technical. All right, here goes: with every
action
> > there is an equal and opposite reaction, no? As you press on the
pedals,
> > where does that energy go? Through the crank, BB, into the frame
through
> > the BB. Worst case, you are standing on the pedals, and all of your
weight
> > goes straight down. Once the pedals are pushed on by your legs, your
body
> > is being forced up and back, some of the force goes sideways, lots goes down.
> >
> > We in agreement?
>
> <sigh> No. If you push downward on the pedals, the force goes downward. Under the usual
> circumstances, it's not true that "some of the force goes sideways."
>
> Honestly, you still have no idea how far you are missing the basics. To begin with, what do you
> mean by "sideways"? Are you talking about situations where the bike is essentially vertical, or
> are you looking at some special case where a person is tilting the bike markedly side to side
> (say, while climbing)? Are you perhaps confusing deflection with force, or assuming that if there
> is a deflection, there must be a force in its direction?
>
> >
> > The harder you push down, the more you are rising off the saddle (or
being
> > pushed backwards), the more lateral force is being exerted through the
BB
> > area, and more goes straight down. The easier you spin, the less these forces are.
> >
> > Right? Feel free to insert the "proper" use of these terms if I'm not getting them exactly right
> > if it helps you to understand what I'm trying
to
> > say.
> >
> > All right, I'm going to stop here and see if we're still together.
>
> Honestly, I don't see how anything you said above is relevant. And it remains true that you are so
> far from understanding the basics - that is, the definitions of force, torque, moment, energy,
> stress, strain, elementary coordinate systems, the concept of a free body diagram, Newton's laws
> of motion, material properties...

All right, so in small words, describe the physics of pedaling a bike better than I tried to.
Remember, I'm from VA and everyone knows we're kinda slow...

Please take into account: BB deflection, the force being exerted on your body every time you press
down on the pedals, and anything else you think is relevent. If you start using complicated
equations, you're going to lose me quicker than I would you talking about investments.

Mike

>
> It's kind of like a jazz musician arguing derivative investments with a stockbroker, using analogy
> to 12-tone music theory. Lots of big words, but little practical meaning.
>
> --
> Frank Krygowski [email protected]

 

[Frank Krygowski]

"Mike S." wrote:
>
> Since material choice affects tubing in all aspects of a bike's design, doesn't it figure into
> ride quality? I know that you could probably engineer an AL frame to ride like steel, and vice
> versa by manipulation of tubing dia, thickness, etc. but the way bikes are engineered now, that's
> not done.

Here's an idea.

Perhaps that last paragraph is what you want to emphasize. Or to put it another way, perhaps what
you want to say is: the CURRENT FASHION is to design frames in such a way that some are stiffer out
of plane, some are less stiff. And the CURRENT FASHION is to design aluminum frames to make them
stiff out of plane. Thus, most CURRENTLY FASHIONABLE aluminum frames will exhibit this tendency.

Of course, the tendency is not impossible to change, and its been different in the past (say, in the
Alan era).

IOW, maybe we can say you're discussing the way things tend to get built these days, while we
engineers are talking about all the possibilities that can be built.

Since we engineers know quite a bit more about the fundamentals, it's easier for us to understand
all the possibilities, not just the ones that are currently common in the marketplace. And since you
(admittedly) don't know the technical vocabulary, some of what you said may have come out wrong,
even though you fundamentally understand a lot of the issues.

Does this work for you?

--
Frank Krygowski [email protected]

 

[Mike S.]

"Frank Krygowski" <[email protected]> wrote in message news:[email protected]...
> "Mike S." wrote:
> >
> > Since material choice affects tubing in all aspects of a bike's design, doesn't it figure into
> > ride quality? I know that you could probably engineer an AL frame to ride like steel, and vice
> > versa by manipulation
of
> > tubing dia, thickness, etc. but the way bikes are engineered now, that's
not
> > done.
>
> Here's an idea.
>
> Perhaps that last paragraph is what you want to emphasize. Or to put it another way, perhaps what
> you want to say is: the CURRENT FASHION is to design frames in such a way that some are stiffer
> out of plane, some are less stiff. And the CURRENT FASHION is to design aluminum frames to make
> them stiff out of plane. Thus, most CURRENTLY FASHIONABLE aluminum frames will exhibit this
> tendency.
>
> Of course, the tendency is not impossible to change, and its been different in the past (say, in
> the Alan era).
>
> IOW, maybe we can say you're discussing the way things tend to get built these days, while we
> engineers are talking about all the possibilities that can be built.

That's an awefully lot of possibilities! You sure about that?
>
> Since we engineers know quite a bit more about the fundamentals, it's easier for us to understand
> all the possibilities, not just the ones that are currently common in the marketplace. And since
> you (admittedly) don't know the technical vocabulary, some of what you said may have come out
> wrong, even though you fundamentally understand a lot of the issues.
>
> Does this work for you?
>
Getting closer. Except the part about the "currently fashionable" part. Since I've been riding a
long time, I've seen that the "currently fashionable" changes regularly. Some of it is marketing,
some of it is a greater understanding of what goes on in riding a bike (forces involved), and some
of it is advances in metallurgy (another topic that I know nothing about), but to say that there's
no difference in the ride between say an Alan and a Cannondale...

I still don't know why y'all think its only the vertical deflection that makes a bike's ride. I was
thinking about this on my ride today. So, again, in small words (I'm from VA...) why exactly is it
that y'all engineers think that it is only the vertical compliance (or lack of) that make a bike's
ride? I'm still trying to see where your assumptions and mine are off. This is especially mind
boggling since we both agree that it (vertical deflection) isn't the only thing happening to a bike
when it is being ridden.

I'm going to try and get Shaun and Eric to go over some of this stuff with me this weekend. At least
after a primer on the forces affecting a bike frame I may be able to argue more effectively, or I
may find I'm completely off base and I owe all of you an apology. I doubt it'll be the latter, but
hey, who knows.

I'm at least man enough to admit that if my model of the forces (using the term generically) acting
on a bike may in fact be wrong, I'll adopt a new one till that one's proven wrong too.
Unfortunately, since it is easier to hold on to an erroneous assumption than to actually adopt a new
one, some of us here may never look past their noses.

Mike

> --
> Frank Krygowski [email protected]

 

[Archer]

In article <[email protected]>, "David L. Johnson" <David
L. Johnson <[email protected]>> says...
> On Wed, 19 Mar 2003 09:35:15 -0500, archer wrote:
>
> > They don't all prefer the same one, but they can tell that there is a difference.
>
> Because they put labels on them, telling you which is which.
>
> > I haven't measured it, but if you are running 160 psi tires on a road in good condition,
>
> Which is already over the top. that is a lot of pressure.
>
> > your tires probably aren't deflecting more than a few thousandths of an inch in response to the
> > normal texture of the road surface, especially if you are a relatively light rider.
>
> I typically ride with more like 100lbs pressure, and though I would not qualify as light, am not
> twice "light". So, my tires would flex probably less than four times the amount you suggest.
> However, on normal roads my tires easily deflect 1/4", and if I lowered the pressure by much below
> that the deflection would be serious enough to invite snake bite flats. So I think your assumption
> here is off by an order of magnitude or more.

Certainly possible, but it would be interesting to measure it.

...

> depending of course on the rider and tire. He also said
> > that the deflection he measured ranged from .001 to .003. That may not seem like much
> > difference, but that factor of three may well be significant in changing the amount of vibration
> > transmitted to the rider.
>
> Not when compared to a 0.1" deflection from the tire.

Remember that we're not talking about the constant deflection from the weight of the rider, but the
_additional_ deflection due to the bump.

> > One thing I haven't seen anybody mention is how the riding speed will affect the ride quality
> > (meaning the amount of vibration and shock transmitted to the rider). There isn't much damping
> > in the vertical direction on non-suspended bicycle, but there is some, and speed will affect the
> > bike's response to road irregularities; it's called resonance, and the stiffness and damping
> > characteristics have major effects on it. Just think of driving your car over a speed bump:
> > there is always a "best" speed to hit it, where your car bounces the least. That is due to the
> > spring rates and damping in the suspension, along with the weight of the car.
>
> True, though that is not resonance. You are talking about the reponse of the system to an external
> input that is something like a delta function, technically called an impulse.

First off, this is not a true impulse function; it's a more complex shape similar to (though not
exactly) a horizontal slice through a sine wave, because the tire _rolls_ up onto the bump and then
back down, rather than being lifted straight up vertically. However, to a first approximation, an
impulse function might be a reasonable comparison, especially at higher speeds.

That being said, IMS, the response of a system to an impulse input is heavily dependent on the
resonant frequency response of a system (tire pressures, spring rates and sprung and unsprung
weights) and its damping coefficient (shocks and hysteresis in the rubber of the tires), but I'd
have to go back through my control systems design textbooks before I would want to argue the point
beyond that.

--
David Kerber An optimist says "Good morning, Lord." While a pessimist says "Good Lord,
it's morning".

Remove the ns_ from the address before e-mailing.

 

[Archer]

In article <MN6ea.143069$L1.18721@sccrnsc02>, [email protected] says...

> The compliance of the tires will be roughly proportional to the inflation pressure, so the 160 psi
> you cite is only a bit less compliant than a nominal 120 psi.

About 1/3 less, it looks like.

> The weight of the rider doesn't enter, since we're talking about the ratio of compliances, which
> would be the same for any load.

The weight of the rider will affect how vibrations at various frequencies dampen out, though.

> > BTW, What do you think about the poster who said he had tried this with identical components on
> > frames which differed only in their construction material, and said he and his customers could
> > tell the difference?
>
> I think it's a perceptual bias, something we humans are notorious for (unlike accelerometers and
> strain gauges). Besides, that's only one individual (or set) of impressions, how about the large
> numbers of us who claim no difference in "harshness" between the bikes (frame materials) we ride?
> We both can't be

How many of us have had a chance to try identical geometries and components with different frame
materials? I wouldn't count on any comparisons without at least that much control in it.

> right, and I'm afraid analysis supports frame material making no contribution to ride comfort.

IMO, here's how the experiment could be set up to take human perceptions out of the result, and
still test for various sizes of bumps, weights of riders and and roughnesses of roads:

Take a bike, any bike, hang some weights on the seat and handlebars in appropriate spots, and attach
accelerometers to the weights. Then place this whole assembly on a shaker table like they use for
vibration testing of mechanical components. These tables can typically be adjusted to give
vibrations of various frequencies and amplitudes through a very wide range. This could test for
resonances at various frequencies, and test for the differences when the amplitude is larger or
smaller than the compliance range of various frames. We could then have a person sit on the bike
while it's being shaken as well, to see if the accelerometer readings give a reasonable correlation
to human perception.

--
David Kerber An optimist says "Good morning, Lord." While a pessimist says "Good Lord,
it's morning".

Remove the ns_ from the address before e-mailing.

 

[Mike S.]

"archer" <ns_archer1960@ns_hotmail.com> wrote in message
news:[email protected]...
> In article <MN6ea.143069$L1.18721@sccrnsc02>, [email protected] says...
>
> > The compliance of the tires will be roughly proportional to the
inflation
> > pressure, so the 160 psi you cite is only a bit less compliant than a
nominal
> > 120 psi.
>
> About 1/3 less, it looks like.
>
> > The weight of the rider doesn't enter, since we're talking about the ratio of compliances, which
> > would be the same for any load.
>
> The weight of the rider will affect how vibrations at various frequencies dampen out, though.
>
>
> > > BTW, What do you think about the poster who said he had tried this
with
> > > identical components on frames which differed only in their
construction
> > > material, and said he and his customers could tell the difference?
> >
> > I think it's a perceptual bias, something we humans are notorious for
(unlike
> > accelerometers and strain gauges). Besides, that's only one individual
(or
> > set) of impressions, how about the large numbers of us who claim no
difference
> > in "harshness" between the bikes (frame materials) we ride? We both
can't be
>
> How many of us have had a chance to try identical geometries and components with different frame
> materials? I wouldn't count on any comparisons without at least that much control in it.
>
> > right, and I'm afraid analysis supports frame material making no
contribution
> > to ride comfort.
>
> IMO, here's how the experiment could be set up to take human perceptions out of the result, and
> still test for various sizes of bumps, weights of riders and and roughnesses of roads:
>
> Take a bike, any bike, hang some weights on the seat and handlebars in appropriate spots, and
> attach accelerometers to the weights. Then place this whole assembly on a shaker table like they
> use for vibration testing of mechanical components. These tables can typically be adjusted to give
> vibrations of various frequencies and amplitudes through a very wide range. This could test for
> resonances at various frequencies, and test for the differences when the amplitude is larger or
> smaller than the compliance range of various frames. We could then have a person sit on the bike
> while it's being shaken as well, to see if the accelerometer readings give a reasonable
> correlation to human perception.
>
>
Except for the part where you are actually supporting some of your own weight with your legs when
you are pedalling...

Like I said in a previous post, if we're going to get into pedaling dynamics, it better be in
another thread.

Mike

> --
> David Kerber An optimist says "Good morning, Lord." While a pessimist says "Good Lord, it's
> morning".
>
> Remove the ns_ from the address before e-mailing.

 

[Peter Cole]

"archer" <ns_archer1960@ns_hotmail.com> wrote in message
news:[email protected]...
> In article <MN6ea.143069$L1.18721@sccrnsc02>, [email protected] says...
>

> The weight of the rider will affect how vibrations at various frequencies dampen out, though.

Again, with respect to the frame, if there is negligible energy being stored, there is negligible
vibration to be damped. Additionally, frame deflections, as small as they are, are not lossy.
Deflections in other materials (rubber, flesh?) are. The frame material just doesn't enter into it.

> > I think it's a perceptual bias, something we humans are notorious for
(unlike
> > accelerometers and strain gauges). Besides, that's only one individual (or set) of impressions,
> > how about the large numbers of us who claim no
difference
> > in "harshness" between the bikes (frame materials) we ride? We both can't
be
>
> How many of us have had a chance to try identical geometries and components with different frame
> materials? I wouldn't count on any comparisons without at least that much control in it.

Static measurement agreed with analysis. There's no reason to believe dynamic measurement wouldn't
also, unless you propose some mechanism which is present dynamically which is undetectable
statically. Hand waving about resonance and damping doesn't work, because all of the components for
these things are measurable statically. This would not be the case for genuinely dynamic conditions
such as steering/balancing etc., but we are talking about "harshness" (butt jiggling, for the
non-technical).

> > right, and I'm afraid analysis supports frame material making no
contribution
> > to ride comfort.
>
> IMO, here's how the experiment could be set up to take human perceptions out of the result, and
> still test for various sizes of bumps, weights of riders and and roughnesses of roads:

All this is unnecessary, unless you can propose some conceivable mechanism to support different
dynamic behavior. Going over a bump is not as complicated as you want to make it.

 

[Archer]

In article <[email protected]>, mikeshaw2@coxDOTnet says...

...

> > Take a bike, any bike, hang some weights on the seat and handlebars in appropriate spots, and
> > attach accelerometers to the weights. Then place this whole assembly on a shaker table like they
> > use for vibration testing of mechanical components. These tables can typically be adjusted to
> > give vibrations of various frequencies and amplitudes through a very wide range. This could test
> > for resonances at various frequencies, and test for the differences when the amplitude is larger
> > or smaller than the compliance range of various frames. We could then have a person sit on the
> > bike while it's being shaken as well, to see if the accelerometer readings give a reasonable
> > correlation to human perception.
> >
> >
> Except for the part where you are actually supporting some of your own weight with your legs when
> you are pedalling...

Yes; that will add some damping, in addition to possibly changing the weight distribution and center
of mass of the bike/rider system. You could attach weights and accelerometers to the pedals, but it
still won't take into account the coupling (both weight and vibration damping) between the rider's
seat and his feet. That would be an interesting 2nd stage of the same kind of testing.

> Like I said in a previous post, if we're going to get into pedaling dynamics, it better be in
> another thread.

Absolutely. I was only talking about vibration, shock and damping in the vertical direction, not how
the frame twists or doesn't due to pedaling forces.

--
David Kerber An optimist says "Good morning, Lord." While a pessimist says "Good Lord,
it's morning".

Remove the ns_ from the address before e-mailing.

 

[Frank Krygowski]

"Mike S." wrote:
>
> "Frank Krygowski" <[email protected]> wrote in message news:[email protected]...
> >
> >
> > Since we engineers know quite a bit more about the fundamentals, it's easier for us to
> > understand all the possibilities, not just the ones that are currently common in the
> > marketplace. And since you (admittedly) don't know the technical vocabulary, some of what you
> > said may have come out wrong, even though you fundamentally understand a lot of the issues.
> >
> > Does this work for you?
> >
> Getting closer. Except the part about the "currently fashionable" part. Since I've been riding a
> long time, I've seen that the "currently fashionable" changes regularly. Some of it is marketing,
> some of it is a greater understanding of what goes on in riding a bike (forces involved), and some
> of it is advances in metallurgy (another topic that I know nothing about), but to say that there's
> no difference in the ride between say an Alan and a Cannondale...
>
> I still don't know why y'all think its only the vertical deflection that makes a bike's ride. I
> was thinking about this on my ride today. So, again, in small words (I'm from VA...) why exactly
> is it that y'all engineers think that it is only the vertical compliance (or lack of) that make a
> bike's ride? I'm still trying to see where your assumptions and mine are off. This is especially
> mind boggling since we both agree that it (vertical deflection) isn't the only thing happening to
> a bike when it is being ridden.

You seem to be forgetting the posts (including one of mine) where different aspects of "ride" were
discussed. One I mentioned was out-of-plane rigidity. Another I mentioned was stability response, as
influenced by frame geometry.

The problem has been, for nearly all this conversation, you were not explaining what you meant by
the nebulous term "ride," and your earliest posts seemed to be concentrating on response to road
irregularities. That aspect of ride, as has been explained ad nauseum, is very unlikely to be
influenced by the microscopic vertical deflections in a frame.

If, indeed, you are including other aspects in the term "ride," then as an engineer, I'd say it's
not very sensible to take completely disparate attributes and try to evaluate them _all_ with one
fuzzy concept like "ride." At the very least, I'd discuss steering stability separately from
out-of-plane rigidity in response to pedal loads. If touring were being contemplated, I'd probably
discuss freedom from shimmy as well ... and so on. One might be better, one might be worse between
two comparable frames.

As an analogy, what would you say if someone said to you "What's the best investment?" Would you not
try to separately discuss things like rate of return, tax implications, level of risk, time to
maturity (if applicable), etc. and evaluate this in terms of the needs and attitudes of the
individual? What would you say to the mechanical engineer who said "Oh, pshaw! Look at this graph!
It's obvious that gold stocks are the best investment, period!"

--
Frank Krygowski [email protected]

 

[Benjamin Lewis]

Mike S. wrote:

> Now we're actually discussing the differences between frames. "The ride" of a bike is a sum of
> everything working on that bike to make it behave the way it does. Vertical stiffness is certainly
> one force, BUT there are others, as you just pointed out: lateral rigidity, etc. that affect how
> "the ride" is percieved by the rider.

Let's change tack slightly. Do you think a frame can be "too stiff"? If so, why?

--
Benjamin Lewis

Marriage causes dating problems.

 

[Mike S.]

Even more fun reading:

http://tam.cornell.edu/~ruina/hplab/downloads/Bicycle_papers/Forces_in_bicyc le_pedalling.PDF>

Thanks, Shaun.

Mike

wrote in message news:[email protected]...
> http://www.chainreaction.com/frame_revelations.htm
>
>
> "archer" <ns_archer1960@ns_hotmail.com> wrote in message
> news:[email protected]...
> > I know Aluminum frames have had a reputation (deserved or not) of being stiff, and I'm wondering
> > if that's still true, with the different alloys they use now. My current bike is a 20+ year old
> > steel-framed Schwinn LeTour (a.k.a LeTank).
> >
> > I'm looking at a Specialized Sequoiah Expert or equivalent, and there seems to be a lot to
> > choose from in that range. Pretty much all the bikes in that price range seem to have aluminum
> > frames with carbon
forks,
> > and I'm curious how the ride might compare between the two (leaving the suspended seat on this
> > particular model out of the equation). The
LeTour
> > has 27 x 1.25, 85psi tires, and the Sequoiah has 700 x 26c tires, but I don't know the pressure.
> >
> > Opinions, please?
> >
> > --
> > David Kerber An optimist says "Good morning, Lord." While a pessimist says "Good Lord, it's
> > morning".
> >
> > Remove the ns_ from the address before e-mailing.

 

[Mike S.]

"Frank Krygowski" <[email protected]> wrote in message news:[email protected]...
> "Mike S." wrote:
> >
> > "Frank Krygowski" <[email protected]> wrote in message news:[email protected]...
> > >
> > >
> > > Since we engineers know quite a bit more about the fundamentals, it's easier for us to
> > > understand all the possibilities, not just the ones that are currently common in the
> > > marketplace. And since you (admittedly) don't know the technical vocabulary, some of what you
said
> > > may have come out wrong, even though you fundamentally understand a
lot
> > > of the issues.
> > >
> > > Does this work for you?
> > >
> > Getting closer. Except the part about the "currently fashionable" part. Since I've been riding a
> > long time, I've seen that the "currently fashionable" changes regularly. Some of it is
> > marketing, some of it is
a
> > greater understanding of what goes on in riding a bike (forces
involved),
> > and some of it is advances in metallurgy (another topic that I know
nothing
> > about), but to say that there's no difference in the ride between say an Alan and a
> > Cannondale...
> >
> > I still don't know why y'all think its only the vertical deflection that makes a bike's ride. I
> > was thinking about this on my ride today. So, again, in small words (I'm from VA...) why exactly
> > is it that y'all engineers think that it is only the vertical compliance (or lack of)
that
> > make a bike's ride? I'm still trying to see where your assumptions and
mine
> > are off. This is especially mind boggling since we both agree that it (vertical deflection)
> > isn't the only thing happening to a bike when it
is
> > being ridden.
>
>
> You seem to be forgetting the posts (including one of mine) where different aspects of "ride" were
> discussed. One I mentioned was out-of-plane rigidity. Another I mentioned was stability response,
> as influenced by frame geometry.
>
> The problem has been, for nearly all this conversation, you were not explaining what you meant by
> the nebulous term "ride," and your earliest posts seemed to be concentrating on response to road
> irregularities. That aspect of ride, as has been explained ad nauseum, is very unlikely to be
> influenced by the microscopic vertical deflections in a frame.
>
> If, indeed, you are including other aspects in the term "ride," then as an engineer, I'd say it's
> not very sensible to take completely disparate attributes and try to evaluate them _all_ with one
> fuzzy concept like "ride." At the very least, I'd discuss steering stability separately from
> out-of-plane rigidity in response to pedal loads. If touring were being contemplated, I'd probably
> discuss freedom from shimmy as well ... and so on. One might be better, one might be worse between
> two comparable frames.

Now we're actually discussing the differences between frames. "The ride" of a bike is a sum of
everything working on that bike to make it behave the way it does. Vertical stiffness is certainly
one force, BUT there are others, as you just pointed out: lateral rigidity, etc. that affect how
"the ride" is percieved by the rider. It seems to me that I'm discussing "the ride" while y'all are
discussing ONE aspect of a frame's behavior that you think determines "the ride." I will agree that
"the ride" is a very fuzzy concept and may be hard for the "everything is black and white" crowd. It
is hard to measure "the ride," because its a little different for everyone: weight, height, riding
style, etc. but what I keep hitting up against is the idea that one of the characteristics of a
frame's "ride" dominates the others, and that the rest of the characteristics do not matter.

Now are we getting somewhere by taking the engineering out of it?

BTW, is that your Seven you told me about? If it is, why exactly did you choose that frame over say
a $695 Habanero if all frames ride exactly the same? Marketing aside, that is. We all know marketing
exists to make you WANT to ride brand X, so they exagerate this characteristic, and downplay others.
I'm just curious if you test rode other Ti frames, and why did you decide on one of THE most
expensive Ti frames out there?

Mike

>
> As an analogy, what would you say if someone said to you "What's the best investment?" Would you
> not try to separately discuss things like rate of return, tax implications, level of risk, time to
> maturity (if applicable), etc. and evaluate this in terms of the needs and attitudes of the
> individual? What would you say to the mechanical engineer who said "Oh, pshaw! Look at this graph!
> It's obvious that gold stocks are the best investment, period!"
>

> --
> Frank Krygowski [email protected]

 

[Frank Krygowski]

"Mike S." wrote:
>
> "Frank Krygowski" <[email protected]> wrote in message news:[email protected]...
>
> > You seem to be forgetting the posts (including one of mine) where different aspects of "ride"
> > were discussed. One I mentioned was out-of-plane rigidity. Another I mentioned was stability
> > response, as influenced by frame geometry.
> >
> > The problem has been, for nearly all this conversation, you were not explaining what you meant
> > by the nebulous term "ride," and your earliest posts seemed to be concentrating on response to
> > road irregularities. That aspect of ride, as has been explained ad nauseum, is very unlikely to
> > be influenced by the microscopic vertical deflections in a frame.
> >
> > If, indeed, you are including other aspects in the term "ride," then as an engineer, I'd say
> > it's not very sensible to take completely disparate attributes and try to evaluate them _all_
> > with one fuzzy concept like "ride." At the very least, I'd discuss steering stability separately
> > from out-of-plane rigidity in response to pedal loads. If touring were being contemplated, I'd
> > probably discuss freedom from shimmy as well ... and so on. One might be better, one might be
> > worse between two comparable frames.
>
> Now we're actually discussing the differences between frames. "The ride" of a bike is a sum of
> everything working on that bike to make it behave the way it does. Vertical stiffness is certainly
> one force, BUT there are others, as you just pointed out: lateral rigidity, etc. that affect how
> "the ride" is percieved by the rider. It seems to me that I'm discussing "the ride" while y'all
> are discussing ONE aspect of a frame's behavior that you think determines "the ride." I will agree
> that "the ride" is a very fuzzy concept and may be hard for the "everything is black and white"
> crowd. It is hard to measure "the ride," because its a little different for everyone: weight,
> height, riding style, etc. but what I keep hitting up against is the idea that one of the
> characteristics of a frame's "ride" dominates the others, and that the rest of the characteristics
> do not matter.
>
> Now are we getting somewhere by taking the engineering out of it?

<sigh> No, we're not. You seem unable to fathom that the behavior of a bike has several unrelated
aspects, and that it actually is possible to measure or numerically describe these aspects. Your
attempt to "take the engineering out of it" is a retreat to the vagueness of undefined terms.

I suggest you re-read the paragraph I wrote (which is below) about the analogy of a "best
investment."

> BTW, is that your Seven you told me about? If it is, why exactly did you choose that frame over
> say a $695 Habanero if all frames ride exactly the same? Marketing aside, that is.

No, I didn't say it was my Seven. I have two friends who own them, and like most of my friends, they
don't mind people test-riding their bikes.

>
> Mike
>
> >
> > As an analogy, what would you say if someone said to you "What's the best investment?" Would you
> > not try to separately discuss things like rate of return, tax implications, level of risk, time
> > to maturity (if applicable), etc. and evaluate this in terms of the needs and attitudes of the
> > individual? What would you say to the mechanical engineer who said "Oh, pshaw! Look at this
> > graph! It's obvious that gold stocks are the best investment, period!"

Think about this, Mike. I believe it's a good analogy to the discussion we've been having.

That said, I'm convinced that Jon is right. We've tried our hardest, but we're not going to get you
to understand these issues. You lack the background. So, I'm done.

--
Frank Krygowski [email protected]

 

[Mike S.]

"Frank Krygowski" <[email protected]> wrote in message news:[email protected]...
> "Mike S." wrote:
> >
> > "Frank Krygowski" <[email protected]> wrote in message news:[email protected]...
> >
> > > You seem to be forgetting the posts (including one of mine) where different aspects of "ride"
> > > were discussed. One I mentioned was out-of-plane rigidity. Another I mentioned was stability
> > > response, as influenced by frame geometry.
> > >
> > > The problem has been, for nearly all this conversation, you were not explaining what you meant
> > > by the nebulous term "ride," and your
earliest
> > > posts seemed to be concentrating on response to road irregularities. That aspect of ride, as
> > > has been explained ad nauseum, is very
unlikely
> > > to be influenced by the microscopic vertical deflections in a frame.
> > >
> > > If, indeed, you are including other aspects in the term "ride," then
as
> > > an engineer, I'd say it's not very sensible to take completely
disparate
> > > attributes and try to evaluate them _all_ with one fuzzy concept like "ride." At the very
> > > least, I'd discuss steering stability separately from out-of-plane rigidity in response to
> > > pedal loads. If touring
were
> > > being contemplated, I'd probably discuss freedom from shimmy as well
...
> > > and so on. One might be better, one might be worse between two comparable frames.
> >
> > Now we're actually discussing the differences between frames. "The
ride" of
> > a bike is a sum of everything working on that bike to make it behave the
way
> > it does. Vertical stiffness is certainly one force, BUT there are
others,
> > as you just pointed out: lateral rigidity, etc. that affect how "the
ride"
> > is percieved by the rider. It seems to me that I'm discussing "the
ride"
> > while y'all are discussing ONE aspect of a frame's behavior that you
think
> > determines "the ride." I will agree that "the ride" is a very fuzzy
concept
> > and may be hard for the "everything is black and white" crowd. It is
hard
> > to measure "the ride," because its a little different for everyone:
weight,
> > height, riding style, etc. but what I keep hitting up against is the
idea
> > that one of the characteristics of a frame's "ride" dominates the
others,
> > and that the rest of the characteristics do not matter.
> >
> > Now are we getting somewhere by taking the engineering out of it?
>
> <sigh> No, we're not. You seem unable to fathom that the behavior of a bike has several unrelated
> aspects, and that it actually is possible to measure or numerically describe these aspects. Your
> attempt to "take the engineering out of it" is a retreat to the vagueness of undefined terms.
>

The "best" investment depends on what you want it to do. Just as the "best" frame material is
dependent on what you want it to do (minus engineering of the bicycle to mimic another material).

I'm not retreating to the vagueness of undefined terms just to screw with anyone, but if we can talk
generally for a moment, maybe we can define what we're aguing about before we go back into
specifics.

And to answer the poster right before this, yes, you can make a bike too stiff. If there is no
compliance anywhere, the bicycle becomes unrideable because it will tend to react immediately to all
the forces involved in the pedaling motion. This would mean the bike would be very uncomfortable and
fatiguing due to the constant "bouncing/juddering" due to every irregularity in pedal stroke and
pavement. Some compliance is necessary, how much is a personal decision.

> I suggest you re-read the paragraph I wrote (which is below) about the analogy of a "best
> investment."
>
>
> > BTW, is that your Seven you told me about? If it is, why exactly did
you
> > choose that frame over say a $695 Habanero if all frames ride exactly
the
> > same? Marketing aside, that is.
>
> No, I didn't say it was my Seven. I have two friends who own them, and like most of my friends,
> they don't mind people test-riding their bikes.

So, why did they buy them? If they have an engineer as a freind to educate them about "the ride" of
a bike, and all frame materials ride the same, why'd they buy an expensive-ass bike when a
Cannondale/Trek/Habanero (or Huffy) would do?

Mike

> >
> > Mike
> >
> > >
> > > As an analogy, what would you say if someone said to you "What's the best investment?" Would
> > > you not try to separately discuss things like rate of return, tax implications, level of risk,
> > > time to maturity (if applicable), etc. and evaluate this in terms of the needs and
attitudes
> > > of the individual? What would you say to the mechanical engineer who said "Oh, pshaw! Look at
> > > this graph! It's obvious that gold stocks
are
> > > the best investment, period!"
>
> Think about this, Mike. I believe it's a good analogy to the discussion we've been having.
>
> That said, I'm convinced that Jon is right. We've tried our hardest, but we're not going to get
> you to understand these issues. You lack the background. So, I'm done.
>
>
> --
> Frank Krygowski [email protected]

 

[Benjamin Lewis]

Mike S. wrote:

> And to answer the poster right before this, yes, you can make a bike too stiff. If there is no
> compliance anywhere, the bicycle becomes unrideable because it will tend to react immediately to
> all the forces involved in the pedaling motion. This would mean the bike would be very
> uncomfortable and fatiguing due to the constant "bouncing/juddering" due to every irregularity in
> pedal stroke and pavement. Some compliance is necessary, how much is a personal decision.

Okay, this is precisely where people are differing from you, I believe. "bouncing/juddering" due to
pavement irregularity is strictly a matter of vertical compliance -- it has nothing to do with
these lateral movements and torsion that you've been talking about, regardless of whether you're
pedaling or not.

I don't see what "irregularity in pedal stroke" has to do with anything we've been discussing.

--
Benjamin Lewis

Line Printer paper is strongest at the perforations.

 

[Mike S.]

"Benjamin Lewis" <[email protected]> wrote in message news:[email protected]...
> Mike S. wrote:
>
> > And to answer the poster right before this, yes, you can make a bike too stiff. If there is no
> > compliance anywhere, the bicycle becomes unrideable because it will tend to react immediately to
> > all the forces involved in the pedaling motion. This would mean the bike would be very
> > uncomfortable and fatiguing due to the constant "bouncing/juddering" due to every irregularity
> > in pedal stroke and pavement. Some compliance is necessary, how much is a personal decision.
>
> Okay, this is precisely where people are differing from you, I believe. "bouncing/juddering" due
> to pavement irregularity is strictly a matter of vertical compliance -- it has nothing to do with
> these lateral movements and torsion that you've been talking about, regardless of whether you're
> pedaling or not.
>
> I don't see what "irregularity in pedal stroke" has to do with anything we've been discussing.

That's the point, it has EVERYTHING with what we're talkin about. I'm going to say it again, if
you're just sitting on a bike, not moving, then every bike is going to feel about the same since
they all have about the same vertical compliance. Its when you are actually riding the bike that the
differences appear.

Prove to me that EVERY bike you've ever ridden has felt exactly the same, has the same lateral
stiffness, the same reaction to pedaling inputs, the same everything, and I'll shut up. Till then,
y'all aren't thinking about what I'm saying, preferring to go on believing what you "know" is true.
At least I'm reading up on this stuff as I'm arguing it, not relying on just my own (limited)
knowledge of the subject. I've got friends that are engineers, even they agree with me that there is
a difference in frames, even though the vertical compliance of all frames are essentially equal. So,
who is right? Depends on what we're talking about.

Since we can't agree on what we're talking about, how can we discuss it? Since I don't know the
"correct" terminology for some of the things I'm trying to explain, it gets harder...

Too bad Frank gave up before he could explain his model of frame behavior, at least then we'd all
know what he was talking about, and could compare to what I'm trying to explain.

Mike

Making a bike too stiff is how Cannondale got its reputation for "harshness." They've been on a
mission to "soften" the ride of their bikes since '88. Why is it y'all can't get that through
your heads?
>
> --
> Benjamin Lewis
>
> Line Printer paper is strongest at the perforations.

 

[Buck]

"Mike S." <mikeshaw2@coxDOTnet> wrote in message news:[email protected]...

<snip>

> Prove to me that EVERY bike you've ever ridden has felt exactly the same, has the same lateral
> stiffness, the same reaction to pedaling inputs, the same everything, and I'll shut up. Till
> then, y'all aren't thinking about what I'm saying, preferring to go on believing what you "know"
> is true.
At
> least I'm reading up on this stuff as I'm arguing it, not relying on just
my
> own (limited) knowledge of the subject. I've got friends that are engineers, even they agree with
> me that there is a difference in frames, even though the vertical compliance of all frames are
> essentially equal. So, who is right? Depends on what we're talking about.
>
> Since we can't agree on what we're talking about, how can we discuss it? Since I don't know the
> "correct" terminology for some of the things I'm trying to explain, it gets harder...

Damn it, Mike! That's what we've been trying to do - find common grounds for discussion! But you
refuse to answer us when we ask you for what you define as the elements that make up the "ride." I
have even suggested you list the parts and how much you think they contribute to the "ride." I will
go even further and ask you to describe how much each plane of motion contributes to the "ride." We
suggested that vertical compliance could be described as "harshness" or softness." We also suggested
that the terms "flexy," "noodly" or "stiff" could refer to lateral flex. "Stability" or
"twitchiness" cound be ascribed to a combination of wheelbase, rake and trail.

With these terms, a bike could be harsh, noodly, but stable. Or it could be soft, inflexible and
unstable. Maybe it could be harsh, stiff and twitchy. Are you starting to get the point? Quit
talking about "ride" and start talking about specific aspects of frame movement and how you perceive
them. Then we can talk about how much each of those aspects of ride are affected by frame geometry,
frame components, and if it is relevant, frame materials.

-Buck