Brakes and older bikes

[Tom Kunich]

Older road racing bikes have limited clearances because everyone was racing on 23 mm clinchers or 22 mm tubulars. Mostly the later because if you got a flat it wouldn't through the tire off of the rim.

So while the fork and rear stay clearances were more than enough to mount wide modern tires the vertical clearances for reasons totally beyond my understanding were often very tight. I assume that this wasn't for reasons of tight clearances but because older aluminum brakes were still made from alloys that flexed and the shorter the brake arm. the more efficient the brakes operated.

But I'm sure that this can all be easily explained by Krygowski who has never ridden anything more high tech than a 5 speed freewheel touring bike with bar end shifters and 27 1/4" tires 1 1/4" wide. He is the kind of person that has led the revolution in mechanical engineering from bicycle to jet engines.

[Frank Krygowski]

On 7/29/2022 4:24 PM, Tom Kunich wrote:
> Older road racing bikes have limited clearances because everyone was racing on 23 mm clinchers or 22 mm tubulars. Mostly the later because if you got a flat it wouldn't through the tire off of the rim.
>
> So while the fork and rear stay clearances were more than enough to mount wide modern tires the vertical clearances for reasons totally beyond my understanding were often very tight. I assume that this wasn't for reasons of tight clearances but because older aluminum brakes were still made from alloys that flexed and the shorter the brake arm. the more efficient the brakes operated.
>

> But I'm sure that this can all be easily explained by Krygowski ...

I can explain a _lot_ about flexing, aluminum alloys and more. I don't
expect Tom to learn anything, of course, but others may be interested.

Tom seems to be implying that newer brakes are made from aluminum alloys
that are stiffer than old aluminum alloys. That's total nonsense. The
engineering property that measures a metal's inherent stiffness is the
Modulus of Elasticity. And (pay attention, Tom) the Modulus of
Elasticity of _any_ aluminum alloy is very close to 10 million psi. (I
won't bother trying to explain the meaning of that value to Tom, but if
anyone else is interested, let me know and I'll explain it.)

So: A super-strong aluminum alloy and a much weaker aluminum alloy have
the same stiffness, within a few percent. If a modern brake does happen
to be stiffer than an older brake, it's not because of the composition
of the alloy. It would have to be because of differences in design - for
example, the shape and size of the cross sections of the relevant parts.

Note, this really is a technical topic! That may disqualify it from
discussion on rec.bicycles.tech! It certainly disqualifies Tom from
saying anything rational.


--
- Frank Krygowski

[ritzann...@gmail.com]

On Friday, July 29, 2022 at 3:24:31 PM UTC-5, cycl...@gmail.com wrote:
> Older road racing bikes have limited clearances because everyone was racing on 23 mm clinchers or 22 mm tubulars. Mostly the later because if you got a flat it wouldn't through the tire off of the rim.
>

Tommy, PROOFREAD your sentences. If you did, you would easily and quickly notice that you meant to write "it wouldn't THROW the tire off the rim". Note, throw, not through. And you used through. I suspect you meant threw. Homophones. Words that sound the same but are spelled differently. Your lack of an education displays itself once again.

[Lou Holtman]

I once shortened my aluminum straight handlebar of my ATB (Ritchey WCS) by a cm on both ends. That left me with two rings of aluminum 10 mm long, 1 mm wall thickness and 26 mm in diameter. I picked them up from the floor and wanted to crush them between my thumb and index finger before throwing them away. I thought that would be easy but I could not do it even if I tried very hard. At that time I used a stainless steel pipe of similar dimensions in one of my designs. A piece of 10 mm of that pipe could be crushed like cheese. I won a lot of bets with those two pieces. What was going on here Frank?

Lou

[Frank Krygowski]

Give us all the details, and it can probably be figured out. But
fundamentally, stiffness (or modulus of elasticity) is a different
property than yield strength. A given metal can be stronger than
another, while being not as stiff.

Also, there are countless alloys of aluminum, and countless alloys of
stainless steel. There are certainly some aluminum alloys stronger than
some stainless steels.

Then there are heat treatments and strain hardening. Strengths of most
alloys can be increased by either or both. Strengths can be decreased
greatly by annealing.

So give us details, please. Exact dimensions would help, as well as
whatever material properties you know.


--
- Frank Krygowski

[Lou Holtman]

I only want to say that the stiffness of a brake arm is not only dependent of the modulus of elasticity of the base material.

Lou

[Jeff Liebermann]

On Sat, 30 Jul 2022 11:33:27 -0400, Frank Krygowski
<frkr...@sbcglobal.net> wrote:

>Also, there are countless alloys of aluminum, and countless alloys of
>stainless steel. There are certainly some aluminum alloys stronger than
>some stainless steels.
>
>Then there are heat treatments and strain hardening. Strengths of most
>alloys can be increased by either or both. Strengths can be decreased
>greatly by annealing.
>
>So give us details, please. Exact dimensions would help, as well as
>whatever material properties you know.

Yep. The stiffness might be the same for various wrought aluminum
alloys, but the tensile and yield strength vary considerably:
<https://www.engineeringtoolbox.com/properties-aluminum-pipe-d_1340.html>
When one tries to stretch aluminum to the point where it will break,
that's the tensile strength. When one tries to stretch aluminum to
the point where it will permanently deform, that's the yield strength.
Crushing a cylinder is the yield strength at the unsupported sides of
the tube. Drawing aluminum tubing introduces directional strengths
where each axis can have different strengths.

"DO YOU KNOW WHICH KIND OF ALLOY EXIST IN YOUR HANDLEBAR?"
<https://www.itm.it/materials/do-you-know-which-kind-of-alloy-exist-in-your-handlebar/>

I would guess(tm) 7075-T6

If one happens to have an eddy current meter for measuring the
conductivity of the handlebars, it will also show the hardness.

--
Jeff Liebermann je...@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

[AMuzi]

For not-handlebars (which are relatively standardized shape
and outer diameter, although of varying thickness and
hardness) there are a gazillion other variables besides
modulus of stiffness. Overall design, cross sections,
fasteners, bushings (steel, nylon, bronze) and so on make
big differences in, say, brakes where alloys are not very
different.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

[Tom Kunich]

It doesn't surprise me that Kragowski wants to play games. https://www.ebay.com/itm/354186333789?hash=item5277268e5d:g:lIcAAOSwKL5i33fL was an older Campy New Record brake and when you were riding behind a man with brakes like this on his bike on a hard descent you could SEE them flex not just the rider feel it. Because of this problem Campy closed the clearances and responded with this: https://www.ebay.com/itm/195240574308?hash=item2d753ebd64:g:w3QAAOSwxspi3VDs but Frank wants you to think that Campy knows nothing about what they were doing.

Frank is a fool that will lie about absolutely anything and then expect people to believe him. Or maybe he's just too stupid to understand anything at all.

[Tom Kunich]

My point was about a matter of leverage as well as alloy. How many people here have complained that they can't stop with Cantilevers? That isn't because of the design but because of the flexing of the arms. But don't mention to Frank that they don't have these problems with V-brakes because of the change in leverage and the clearances.

[Luns Tee]

Indeed. Steel is universally ~3x stiffer than aluminum, but not necessarily stronger. If I'm reading things correctly, yield strength for 304 stainless is 215MPa. 7075T6 is 503MPa.

> So give us details, please. Exact dimensions would help, as well as
> whatever material properties you know.

I think the sensitivity to dimensions is greatly understated here. Barring a brain fart on my part, stiffness goes with the cube of the wall thickness in this case, and yield strength with the square. The difference between 1.1mm and 0.8mm accounts for an almost 2x difference in strength, when both are arguably quite similar to 1mm.

-Luns

[John B.]

Ah well.... if Frank made a mistake that is 1 Frank, while Tommy boy
is wrong hundreds of times? Thousands of times?

So Frank - 1, Tommy - so many they can't be counted.
--
Cheers,

John B.

[Frank Krygowski]

I made no mistake.

Tom is once again inventing things he _pretends_ I said. I said nothing
specific about those two brakes. What I disputed was his implication
that the difference was the stiffness of the old and new aluminum
alloys. "older aluminum brakes were still made from alloys that flexed"
was bullshit from someone who doesn't understand elementary metallurgy.

As usual, Tom is not smart enough or brave enough to address what I've
actually said.

--
- Frank Krygowski

[Frank Krygowski]

On 7/30/2022 4:11 PM, Tom Kunich wrote:
>
> My point was about a matter of leverage as well as alloy.

Leverage - technically known as Mechanical Advantage - does matter. I
addressed that.

"... older aluminum brakes were still made from alloys that flexed ..."
is ignorant bullshit from Tom. Aluminum alloy stiffnesses have not changed.

> How many people here have complained that they can't stop with Cantilevers? That isn't because of the design but because of the flexing of the arms.

That's a different piece of bullshit.

--
- Frank Krygowski

[Frank Krygowski]

I covered that already, when I said "If a modern brake does happen to be

stiffer than an older brake, it's not because of the composition of the
alloy. It would have to be because of differences in design - for
example, the shape and size of the cross sections of the relevant parts."

Sounds like we are once again in furious agreement.

--
- Frank Krygowski

[Jeff Liebermann]

On Sat, 30 Jul 2022 13:11:37 -0700 (PDT), Tom Kunich
<cycl...@gmail.com> wrote:

>My point was about a matter of leverage as well as alloy. How many people here have complained that they can't stop with Cantilevers? That isn't because of the design but because of the flexing of the arms. But don't mention to Frank that they don't have these problems with V-brakes because of the change in leverage and the clearances.

Please try not to confuse handlebars with brake arms. My comments
about handlebar material were in response to Frank Krygowski's
comments, in answer to the following question by Lou Holtman on his
inability to bend or crush a short piece of aluminum tube cut from the
end of his handlebars. This has nothing to do with the aluminum used
to make brake arms, which are forged, cast, or stamped, while
handlebars are extruded:

From Lou Holtman:

"I once shortened my aluminum straight handlebar of my ATB (Ritchey
WCS) by a cm on both ends. That left me with two rings of aluminum 10
mm long, 1 mm wall thickness and 26 mm in diameter. I picked them up
from the floor and wanted to crush them between my thumb and index
finger before throwing them away. I thought that would be easy but I
could not do it even if I tried very hard. At that time I used a
stainless steel pipe of similar dimensions in one of my designs. A
piece of 10 mm of that pipe could be crushed like cheese. I won a lot
of bets with those two pieces. What was going on here Frank?"

[John B.]

On Sat, 30 Jul 2022 18:07:22 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:

While I'm not going to get into another "I did this", "you did that" I
would ask what sort of stainless tube/pipe the bloke was crushing like
cheese? And, yes, I have used stainless tubing and pipes for various
purposes.
An ASTM standard stainless "3/4" pipe" has an O.D. of 1.050" and a
wall thickness of 0.065", or about 1/16", 1.65mm.
https://www.unifiedalloys.com/p/stainless-steel-pipe-data

--
Cheers,

John B.

[John B.]

Please note, I didn't say that "Frank made a mistake", I said "IF
Frank made a mistake". There is a difference (:-)
--
Cheers,

John B.

[AMuzi]

Isn't torsional rigidity a cube of the minor diameter?
ISTR strength is linear to wall thickness, but I could be wrong.

[Frank Krygowski]

Understood.

--
- Frank Krygowski

[Frank Krygowski]

Your "torsional rigidity" probably means the Polar Moment of Inertia.

For a tube, Angular deflection is Theta = Torque * Length / (torsional
modulus of elasticity * polar moment of inertia)

Polar Moment of Inertia of a tube is pi/32 *(D^4 - d^4)

> ISTR strength is linear to wall thickness, but I could be wrong.

What strength situation? We seem to have gone from bending rigidity
and/or bending strength in brake arms to lateral crushing of a tube. I'm
not sure where we are now.

--
- Frank Krygowski

[Tom Kunich]

I', sure that after Frank said I I said that the clearances on the older bikes were tightened up to make the brake arms shorter that he actually didn't say that it was the alloy and not the actual strength of the brake arm we were speaking of. Frank is of the opinion that the component manufacturers don't know what they're doing when they make the brake arms heavier so that they can open the clearances.

[Frank Krygowski]

Poor Tom. He's _so_ out of his depth here.

--
- Frank Krygowski

[Luns Tee]

On Sunday, July 31, 2022 at 6:27:54 AM UTC-7, AMuzi wrote:

> On 7/30/2022 5:40 PM, Luns Tee wrote:
> > On Saturday, July 30, 2022 at 8:33:32 AM UTC-7, Frank Krygowski wrote:
> >> On 7/30/2022 3:28 AM, Lou Holtman wrote:
> >>> I once shortened my aluminum straight handlebar of my ATB (Ritchey WCS) by a cm on both ends. That left me with two rings of aluminum 10 mm long, 1 mm wall thickness and 26 mm in diameter. I picked them up from the floor and wanted to crush them between my thumb and index finger before throwing them away. I thought that would be easy but I could not do it even if I tried very hard. At that time I used a stainless steel pipe of similar dimensions in one of my designs. A piece of 10 mm of that pipe could be crushed like cheese. I won a lot of bets with those two pieces. What was going on here Frank?

> >> So give us details, please. Exact dimensions would help, as well as
> >> whatever material properties you know.
> >
> > I think the sensitivity to dimensions is greatly understated here. Barring a brain fart on my part, stiffness goes with the cube of the wall thickness in this case, and yield strength with the square. The difference between 1.1mm and 0.8mm accounts for an almost 2x difference in strength, when both are arguably quite similar to 1mm.

> Isn't torsional rigidity a cube of the minor diameter?
> ISTR strength is linear to wall thickness, but I could be wrong.

For torsional loading, yes the rigidity would go with the cube of the diameter and both rigidity and strength would go linearly with wall thickness. However, the loading under consideration was Lou's description of crushing a ring, presumably across its diameter, between thumb and index finger. Torsion would somehow grabbing both ends of a tube and twisting it.

For the crush loading described, the bending force tends to flatten the ring - increasing the radius - at the loading points (call them top/bottom), and pinching down the ring - reducing radius - at the left/right sides of the ring. There's an inflection point of sorts that divides these two effects at which there's only a compressive and shear loading, but no bending.

If you consider the ring between each loading point and the two adjacent inflection points, it's largely the same as a three-point bending test of a simple beam. The fact that the beam is curved doesn't affect the cubic and square dependency of stiffness and strength on thickness. The left/right sections are related to a compression buckling analysis, but again have the same dependencies on wall thickness.

On Sunday, July 31, 2022 at 7:59:28 AM UTC-7, Frank Krygowski wrote:
> Polar Moment of Inertia of a tube is pi/32 *(D^4 - d^4)

which I like to write as pi/32 *(D - d)(D^3 + D^2*d+D*D^2 + d^3)

For a sufficiently thin wall, the D-d=2t is the main thing that matters with wall thickness, with D^3 and d^3 and the terms in between all being close enough to approximate as identical, leaving something like pi/4*t*D^3

-Luns

[AMuzi]

That was helpful, THX

[Tom Kunich]

Well, I have an older steel bike in which they started with long arm thinner cross section brakes, reduced the arm length to reduce the beam length to reduce bending stress and then increased the cross section of the brakes to increase the length of the arm with the same strength with more clearance.

Frank as a mechanical engineer understood me perfectly but chose to scream names. He has never forgiven me for actually working as an engineer while he has contributed nothing to the world. Teachers are a dime a dozen and every one of them have an over-inflated idea of their worth. I was completing designs and projects with PhD's working for me who couldn't keep up. Their opinions of their abilities wouldn't allow them to do anything but one way. In my case it even almost killed me in a poison gas chamber where they allow zero safety factor in the time they told me the chamber would be safe. Was it my fault for assuming that ANY reasonable person would allow a safety factor or theirs for not adding a safety factor? Both I guess, but it was me that was entering and leaving that chamber and not them. They were safely in another building.

[Frank Krygowski]

Well done. +1


--
- Frank Krygowski

[funkma...@hotmail.com]

On Monday, August 1, 2022 at 11:00:11 AM UTC-4, cycl...@gmail.com wrote:
> On Sunday, July 31, 2022 at 9:51:20 PM UTC-7, Luns Tee wrote:
>
> >
> > For a sufficiently thin wall, the D-d=2t is the main thing that matters with wall thickness, with D^3 and d^3 and the terms in between all being close enough to approximate as identical, leaving something like pi/4*t*D^3

> Well, I have an older steel bike in which they started with long arm thinner cross section brakes, reduced the arm length to reduce the beam length to reduce bending stress and then increased the cross section of the brakes to increase the length of the arm with the same strength with more clearance.

And of course Frank, Luns, and Lou are talking about physical characteristics of tubing, while sparky thinks it has relevance to brake arms (even after Jeff cautioned you to not confuse the two).

> Frank as a mechanical engineer understood me perfectly but chose to scream names.

Yer a real piece o'work, sparky. You opened this thread with an insult to Frank. After he responded with real, actual technical information, you called him a fool and liar. So, who is it that's responding with name calling?

> He has never forgiven me for actually working as an engineer

Liar - you never worked as an engineer, your resume is simply lies

> while he has contributed nothing to the world. Teachers are a dime a dozen and every one of them have an over-inflated idea of their worth.

Says the technician who had 15 jobs in 20 years and insists fiber optics are called "light lines"

> I was completing designs and projects with PhD's working for me who couldn't keep up.

Bullshit - they were giving you enough space so that when you blew something up they wouldn't get caught up in the blast, and they never worked _for_ you.

> Their opinions of their abilities wouldn't allow them to do anything but one way.

To translate - "They wouldn't help me do it wrong"

> In my case it even almost killed me in a poison gas chamber where they allow zero safety factor in the time they told me the chamber would be safe.

Though the idea that they would have been tempted to send _you_ into a gas chamber before it was cleared out is plausible, it's highly unlikely. What's more likely is that you weren't paying attention and went into the chamber before it was cleared. Here's how we know this: If it were in fact true that you were given the all clear from someone responsible, you would be a very rich man right now from winning the lawsuit. This is how we know it was your fault.

[Luns Tee]

On Monday, August 1, 2022 at 8:46:25 AM UTC-7, funkma...@hotmail.com wrote:
> On Monday, August 1, 2022 at 11:00:11 AM UTC-4, cycl...@gmail.com wrote:
> > On Sunday, July 31, 2022 at 9:51:20 PM UTC-7, Luns Tee wrote:
> > > For a sufficiently thin wall, the D-d=2t is the main thing that matters with wall thickness, with D^3 and d^3 and the terms in between all being close enough to approximate as identical, leaving something like pi/4*t*D^3
>
> > Well, I have an older steel bike in which they started with long arm thinner cross section brakes, reduced the arm length to reduce the beam length to reduce bending stress and then increased the cross section of the brakes to increase the length of the arm with the same strength with more clearance.
> And of course Frank, Luns, and Lou are talking about physical characteristics of tubing, while sparky thinks it has relevance to brake arms (even after Jeff cautioned you to not confuse the two).

In all fairness however, this thread was started as a post contemplating brake arms. The tubing discussion was a diversion from that, not vice-versa. There is an underlying relevance that permitted the original diversion, and I think it's fair to try to steer things back to the original discussion. To that end:

> On 7/29/2022 4:24 PM, Tom Kunich wrote:
> > So while the fork and rear stay clearances were more than enough to mount wide modern tires the vertical clearances for reasons totally beyond my understanding were often very tight. I assume that this wasn't for reasons of tight clearances but because older aluminum brakes were still made from alloys that flexed and the shorter the brake arm. the more efficient the brakes operated.

On Friday, July 29, 2022 at 6:54:24 PM UTC-7, Frank Krygowski wrote:
> Tom seems to be implying that newer brakes are made from aluminum alloys
> that are stiffer than old aluminum alloys. That's total nonsense.

I agree with what has been said here, both by Tom and Frank. Where the problem lies is in things which were not explicitly said, but implied. Referring to alloys that were still used implies that those alloys are no longer used. There's no value in distinguishing old vs newer alloys unless there's some significance in the difference between them, and Frank's point is that aluminum alloys, old or new, are all identical as far as modulus (flex) goes.

I don't know whether it's just Tom's nature to regularly pepper his writing with either irrelevant details or omissions, or if it's done specifically to bait Frank or others (though the next sentance of the opening post is very clearly the latter). Either way, he seems to react as if the baby has been thrown out any time somebody even suggests that the bathwater is dirty.

This could have easily avoided if only the original post had instead read:

> > So while the fork and rear stay clearances were more than enough to mount wide modern tires the vertical clearances for reasons totally beyond my understanding were often very tight. I assume that this wasn't for reasons of tight clearances but because older long-reach aluminum brakes flexed and the shorter the brake arm. the more efficient the brakes operated.

To that point, I think it's plausible. Shorter reach contributes to stiffer, better brakes, and I don't think anybody has argued otherwise. Whether it was the actual motivation for reduced tire clearance, or just a fortuitous side-effect of that fashion, I don't think we'll ever know.

-Luns

[Tom Kunich]

The comments that newer aluminum alloys are not stiffer are total nonsense. Brake arms are not hollow and Frank's bringing tube strength into it was nonsense. You can get these same older brakes from Ebay and install them and pull the brakes and WATCH them flex. Yes a large part if this is due to the length of the arms but the specific alloy used today has higher stiffness. And Campy is attempting to reduce the mass of the braking system to take advantage of two things - the higher stiffness of modern alloys and the increased mechanical stiffness of the design. This not a case of Frank not knowing this - it is a case of him feeling required to argue about it because I have so little respect for engineers that don't actually work in the field. If you're not faced every day by problems for which you are financially required to find solutions you don't pretend to know about it.

[funkma...@hotmail.com]

On Monday, August 1, 2022 at 3:03:21 PM UTC-4, cycl...@gmail.com wrote:
>
> The comments that newer aluminum alloys are not stiffer are total nonsense.

Can you give us an example of a _new_ alloy used in the manufacture of bike components that is inherently stiffer - one that has not existed for the past 50 years?

> Brake arms are not hollow and Frank's bringing tube strength into it was nonsense.

Frank didn't bring tube strength into it, you asshat. He was responding to a question from Lou.

> You can get these same older brakes from Ebay and install them and pull the brakes and WATCH them flex. Yes a large part if this is due to the length of the arms but the specific alloy used today has higher stiffness.

They aren't using anything new. They have transitioned to higher strength alloys and they've done some innovative things with manufacturing methods, but they aren't using any "new" alloys.

> And Campy is attempting to reduce the mass of the braking system to take advantage of two things - the higher stiffness of modern alloys and the increased mechanical stiffness of the design.
> This not a case of Frank not knowing this - it is a case of him feeling required to argue about it because I have so little respect for engineers that don't actually work in the field.

No, it's because you're wrong. As usual, you make up crap, and start of a thread with a unrelated personal attack. You get pissed off because you make claims you can't back up and get called out on it. Your problem is that you _think_ you know everything but are proven wrong on a daily basis, and are so insecure that you have to attack rather than admit you might be wrong.

> If you're not faced every day by problems for which you are financially required to find solutions you don't pretend to know about it.

That explains why your broke ass is living in your mothers house.

[funkma...@hotmail.com]

On Monday, August 1, 2022 at 2:46:13 PM UTC-4, Luns Tee wrote:
> On Monday, August 1, 2022 at 8:46:25 AM UTC-7, funkma...@hotmail.com wrote:
> > On Monday, August 1, 2022 at 11:00:11 AM UTC-4, cycl...@gmail.com wrote:
> > > On Sunday, July 31, 2022 at 9:51:20 PM UTC-7, Luns Tee wrote:
> > > > For a sufficiently thin wall, the D-d=2t is the main thing that matters with wall thickness, with D^3 and d^3 and the terms in between all being close enough to approximate as identical, leaving something like pi/4*t*D^3
> >
> > > Well, I have an older steel bike in which they started with long arm thinner cross section brakes, reduced the arm length to reduce the beam length to reduce bending stress and then increased the cross section of the brakes to increase the length of the arm with the same strength with more clearance.
> > And of course Frank, Luns, and Lou are talking about physical characteristics of tubing, while sparky thinks it has relevance to brake arms (even after Jeff cautioned you to not confuse the two).
> In all fairness however, this thread was started as a post contemplating brake arms. The tubing discussion was a diversion from that, not vice-versa. There is an underlying relevance that permitted the original diversion, and I think it's fair to try to steer things back to the original discussion. To that end:

True, the tubing discussion was a bit of a subthread, and unrelated to the OP. Tom got pissy because they were having a meaningful exchange without his involvement

> > On 7/29/2022 4:24 PM, Tom Kunich wrote:
> > > So while the fork and rear stay clearances were more than enough to mount wide modern tires the vertical clearances for reasons totally beyond my understanding were often very tight. I assume that this wasn't for reasons of tight clearances but because older aluminum brakes were still made from alloys that flexed and the shorter the brake arm. the more efficient the brakes operated.
> On Friday, July 29, 2022 at 6:54:24 PM UTC-7, Frank Krygowski wrote:
> > Tom seems to be implying that newer brakes are made from aluminum alloys
> > that are stiffer than old aluminum alloys. That's total nonsense.
> I agree with what has been said here, both by Tom and Frank. Where the problem lies is in things which were not explicitly said, but implied. Referring to alloys that were still used implies that those alloys are no longer used. There's no value in distinguishing old vs newer alloys unless there's some significance in the difference between them, and Frank's point is that aluminum alloys, old or new, are all identical as far as modulus (flex) goes.
>
> I don't know whether it's just Tom's nature to regularly pepper his writing with either irrelevant details or omissions, or if it's done specifically to bait Frank or others (though the next sentance of the opening post is very clearly the latter). Either way, he seems to react as if the baby has been thrown out any time somebody even suggests that the bathwater is dirty.

Yes, both are in his nature. He will often start a thread about his ride that day that turns into a qanon screed in which he insults several people in this forum. Then his circle-jerk buddy andre chimes in and makes even bigger fools of both himself and tom.

[Frank Krygowski]

That's all very reasonable. I'll mention that even for longer reach
brakes, the stiffness of the brake arms could have been increased, if
desired, by changing the dimensions of the cross section. But that would
have almost certainly have added mass; and in those days, perhaps even
more than today, people were obsessed with gram counts. (Remember
"drillium"?)

Longer arms would tend to lead to lower mechanical advantage, if other
things were held equal. But that could have been addressed in other
ways. I understand there are long reach dual pivots that have very
acceptable mechanical advantage. And browsing through _The Data Book_
will reveal dozens of unusual approaches to brake design.

All these factors must work together to produce a good brake design. But
it is certainly NOT true that the stiffness of relevant aluminum alloys
has increased significantly.

Or perhaps I should say: If Tom (hah!) or anyone else has evidence that
there's been a big increase in the modulus of elasticity of relevant
aluminum alloys, I'd really like to see some documentation.


--
- Frank Krygowski

[Frank Krygowski]

On 8/1/2022 3:03 PM, Tom Kunich wrote:
>
> The comments that newer aluminum alloys are not stiffer are total nonsense.

OK, show us your evidence. The property that matters is the Modulus of
Elasticity, usually abbreviated E.

Show us an aluminum alloy that has E = 11 million psi, instead of the
typical value of 10 million to 10.3 million psi.


--
- Frank Krygowski

[Tom Kunich]

I received a package of brakes today that said Record on the outside of the package. It also said that they were both dual pivot brakes. I had ordered Chorus. Well, it they were Record that was fine with me, not that I think that there is any significant difference between Chorus and Record. That guy must have been the worlds most careful unpacker since when I cut the Campy seal and opened the package they were Chorus So I removed the dual pivot rear brake went down into the garage and installed it on the Moser and set it up there was sufficient clearance to allow the 28 mm tire to fit with plenty of clearance.

So I placed the single pivot Record brake back into the package and will be able to sell the brake set off separately. and retrieve my money on the new brake set. Now if the dual pivot brake is without a cable the ends do drag against the large tire but properly adjusted there is good clearance. Now I have tried the older Daytona dual pivot brake on and it didn't have sufficient clearance so I couldn't use any of the older braking systems I had to buy new.

[Luns Tee]

I think there's a whole discussion of where one draws the line for whether a particular alloy can still be called an aluminum alloy, and when you need to at least hyphenate it to something else. There are aluminum-lithium alloys which are about in that neighbourhood which sometimes get referred to as just being aluminum alloys. Take Alcoa 2090-T84 for example: 76GPa (11Mpsi) modulus.

I don't know for a fact whether this or similar alloys are actually used for bike components or not, but given they're 3x the cost, I doubt it. I don't even know if these alloys are used in anything other than sheet form or extrusions.

But there's also the question of whether a 10% difference in modulus counts as significant or not, too. If you're squeezing hard enough that 1mm of your brake lever travel is due to flex, can you really detect if you're squeezing 9mm instead? Compare this with the difference between 49mm and 39mm reach. Call these 40 and 50. Assuming identical cross-section geometry, but otherwise scaling the paths of the brake arms accordingly, the shorter arm is 1.25^2=1.56x as stiff.

[Luns Tee]

On Monday, August 1, 2022 at 7:30:11 PM UTC-7, Luns Tee wrote:
> But there's also the question of whether a 10% difference in modulus counts as significant or not, too. If you're squeezing hard enough that 1mm of your brake lever travel is due to flex, can you really detect if you're squeezing 9mm instead? Compare this with the difference between 49mm and 39mm reach. Call these 40 and 50. Assuming identical cross-section geometry, but otherwise scaling the paths of the brake arms accordingly, the shorter arm is 1.25^2=1.56x as stiff.

.. continuing as Google groups posted prematurely. I miss my trn.

Of course the assumption of identical cross-sectional geometry is never seen in practice, but the real point is that differences in geometry play a far bigger role than differences in material properties between different aluminum alloys. Thicker, heavier arms are of course the simplest geometric change to make. Campagnolo and SRAM making a triangle out of the Y arm (similar to older cantilever brake arms) would be another.

-Luns

[Luns Tee]

On Monday, August 1, 2022 at 7:30:11 PM UTC-7, Luns Tee wrote:

> But there's also the question of whether a 10% difference in modulus counts as significant or not, too. If you're squeezing hard enough that 1mm of your brake lever travel is due to flex, can you really detect if you're squeezing 9mm instead? Compare this with the difference between 49mm and 39mm reach. Call these 40 and 50. Assuming identical cross-section geometry, but otherwise scaling the paths of the brake arms accordingly, the shorter arm is 1.25^2=1.56x as stiff.

This should of course have read 1cm rather than 1mm.

-Luns

[Tom Kunich]

Well consider it in terms of English measurements. The alloy those old Campy Super Record breaks had am E of 68 and the commonly use 7075 has an E of almost 72 or over 100.000 psi different. While Frank wants to pretend that is no difference at all, it is in fact a large difference. I consider a 4% increase in bending strength a great deal especially when combined with a redesign of the mechanical structure to put perhaps less material but with higher leverage. Again, Frank is pretending that Campagnolo engineers don't know what they're doing. According to him modern brakes bend as much as the old Super Record brakes.

[Tom Kunich]

The idea was to squeeze just hard enough to slow down ENOUGH While I am in complete agreement with your comments about geometry being more important than the exact alloy. The increase in the modulus of elasticity is still significant. The brake arms have to wrap around the tire and push on the rim.

[AMuzi]

Typical (many Campagnolo components including brake
caliperss) aluminum alloy here:
https://www.barate.it/en/products/alloy-2024-avional-150

[funkma...@hotmail.com]

On Monday, August 1, 2022 at 10:51:33 PM UTC-4, cycl...@gmail.com wrote:
> On Monday, August 1, 2022 at 7:30:11 PM UTC-7, Luns Tee wrote:
> > On Monday, August 1, 2022 at 6:05:56 PM UTC-7, Frank Krygowski wrote:
> > > On 8/1/2022 3:03 PM, Tom Kunich wrote:
> > > >
> > > > The comments that newer aluminum alloys are not stiffer are total nonsense.
> > > OK, show us your evidence. The property that matters is the Modulus of
> > > Elasticity, usually abbreviated E.
> > >
> > > Show us an aluminum alloy that has E = 11 million psi, instead of the
> > > typical value of 10 million to 10.3 million psi.
> > I think there's a whole discussion of where one draws the line for whether a particular alloy can still be called an aluminum alloy, and when you need to at least hyphenate it to something else. There are aluminum-lithium alloys which are about in that neighbourhood which sometimes get referred to as just being aluminum alloys. Take Alcoa 2090-T84 for example: 76GPa (11Mpsi) modulus.
> >
> > I don't know for a fact whether this or similar alloys are actually used for bike components or not, but given they're 3x the cost, I doubt it. I don't even know if these alloys are used in anything other than sheet form or extrusions.
> >
> > But there's also the question of whether a 10% difference in modulus counts as significant or not, too. If you're squeezing hard enough that 1mm of your brake lever travel is due to flex, can you really detect if you're squeezing 9mm instead? Compare this with the difference between 49mm and 39mm reach. Call these 40 and 50. Assuming identical cross-section geometry, but otherwise scaling the paths of the brake arms accordingly, the shorter arm is 1.25^2=1.56x as stiff.
> Well consider it in terms of English measurements.

Real engineers can work with either, sparky.

>The alloy those old Campy Super Record breaks had am E of 68 and the commonly use 7075 has an E of almost 72 or over 100.000 psi different.

Do you have a reference for this, or are you - as usual - just pulling it out of your ass? Considering the E values of aluminum alloys are all in the 10M range, these 68 and 72 numbers are completely irrelevant, I think it's likely you're confusing Modulus of Elasticity with Young's Modulus. Here's a handy chart for your reference - we know, we know sparky, never trust anything you read on the web, we should instead take your word for it, right?

https://www.engineeringtoolbox.com/properties-aluminum-pipe-d_1340.html

And before you go on a rant about "properties-aluminum-pipe", the web page isn't specific to pipe.

> While Frank wants to pretend that is no difference at all, it is in fact a large difference. I consider a 4% increase in bending strength a great deal especially when combined with a redesign of the mechanical structure to put perhaps less material but with higher leverage.

Too bad you're considering the wrong property

> Again, Frank is pretending that Campagnolo engineers don't know what they're doing. According to him modern brakes bend as much as the old Super Record brakes.

Point to where he stated that?

[funkma...@hotmail.com]

On Tuesday, August 2, 2022 at 8:33:07 AM UTC-4, AMuzi wrote:
>
> Typical (many Campagnolo components including brake
> caliperss) aluminum alloy here:
> https://www.barate.it/en/products/alloy-2024-avional-150

Where did you get the information that this specific 2024 alloy is the type used by Campy for their components? Tommy is claiming they use 7075.

[AMuzi]

On 8/2/2022 10:01 AM, funkma...@hotmail.com wrote:
> On Tuesday, August 2, 2022 at 8:33:07 AM UTC-4, AMuzi wrote:
>>
>> Typical (many Campagnolo components including brake
>> caliperss) aluminum alloy here:
>> https://www.barate.it/en/products/alloy-2024-avional-150
>
> Where did you get the information that this specific 2024 alloy is the type used by Campy for their components? Tommy is claiming they use 7075.
>
>
>
>

Campagnolo wrote Avional for years, can't find any current
mention of alloy used:

https://velobase.com/ViewComponent.aspx?ID=532fa429-4cd0-48d8-90cd-1f60ecb92a3d.

[Frank Krygowski]

On 8/1/2022 10:51 PM, Tom Kunich wrote:
> On Monday, August 1, 2022 at 7:30:11 PM UTC-7, Luns Tee wrote:
>> On Monday, August 1, 2022 at 6:05:56 PM UTC-7, Frank Krygowski wrote:
>>> On 8/1/2022 3:03 PM, Tom Kunich wrote:
>>>>
>>>> The comments that newer aluminum alloys are not stiffer are total nonsense.
>>> OK, show us your evidence. The property that matters is the Modulus of
>>> Elasticity, usually abbreviated E.
>>>
>>> Show us an aluminum alloy that has E = 11 million psi, instead of the
>>> typical value of 10 million to 10.3 million psi.
>> I think there's a whole discussion of where one draws the line for whether a particular alloy can still be called an aluminum alloy, and when you need to at least hyphenate it to something else. There are aluminum-lithium alloys which are about in that neighbourhood which sometimes get referred to as just being aluminum alloys. Take Alcoa 2090-T84 for example: 76GPa (11Mpsi) modulus.
>>
>> I don't know for a fact whether this or similar alloys are actually used for bike components or not, but given they're 3x the cost, I doubt it. I don't even know if these alloys are used in anything other than sheet form or extrusions.
>>
>> But there's also the question of whether a 10% difference in modulus counts as significant or not, too. If you're squeezing hard enough that 1mm of your brake lever travel is due to flex, can you really detect if you're squeezing 9mm instead? Compare this with the difference between 49mm and 39mm reach. Call these 40 and 50. Assuming identical cross-section geometry, but otherwise scaling the paths of the brake arms accordingly, the shorter arm is 1.25^2=1.56x as stiff.
>
> Well consider it in terms of English measurements. The alloy those old Campy Super Record breaks had am E of 68 and the commonly use 7075 has an E of almost 72 or over 100.000 psi different.

??? AFAIK there is no "English" measurement of modulus of elasticity of
aluminum alloys that gives values of 68 or 72 (times ten to any power).

> While Frank wants to pretend that is no difference at all, it is in fact a large difference.

IF those values were correct, they would be a difference of about six
percent, which would hardly be transformational. Given that the numbers
apparently popped out of your ... um, imagination, they're meaningless.

> I consider a 4% increase in bending strength a great deal ...

Are you suddenly talking about bending instead of material stiffness,
AKA modulus of elasticity? Do you really not know the difference??

Bending strength, as in resistance to yielding, is largely irrelevant
for most bike brake parts. In fact, in one in-class exercise, I had
students measure their grip strengths, then calculate the approximate
bending strength of a caliper brake lever I supplied. They were puzzled
that the lever seemed not strong enough to resist some student's grips.
Finally, I used a bolt in place of a cable to hold the lever open and
had one fairly strong guy squeeze as hard as he could. He folded the lever.

The point was, it didn't _need_ to resist maximum grip, because that's
essentially never applied. Pitchover is the limit of bike braking. The
lever was designed for practical use, in which braking force is limited
by bike physics.

> Again, Frank is pretending that Campagnolo engineers don't know what they're doing. According to him modern brakes bend as much as the old Super Record brakes.

No, I'm claiming that Tom Kunich knows nothing about mechanical design.


--
- Frank Krygowski

[Jeff Liebermann]

On Tue, 2 Aug 2022 07:52:24 -0700 (PDT), "funkma...@hotmail.com"
<funkma...@hotmail.com> wrote:

>I think it's likely you're confusing Modulus of Elasticity with Young's Modulus.

Young's Modulus, Modulus of Elasticity, and Elastic Modulus are the
same, long as we're talking about tension:
<https://www.engineeringtoolbox.com/young-modulus-d_417.html>
<https://en.wikipedia.org/wiki/Elastic_modulus>
Both terms are the ratio of tensile (pulling) stress to strain, or the
slope of the curve just prior to permanent deformation (yield point).
<https://en.wikipedia.org/wiki/Stress%E2%80%93strain_curve>

--
Jeff Liebermann je...@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

[funkma...@hotmail.com]

On Tuesday, August 2, 2022 at 12:55:05 PM UTC-4, Frank Krygowski wrote:
> On 8/1/2022 10:51 PM, Tom Kunich wrote:
> > On Monday, August 1, 2022 at 7:30:11 PM UTC-7, Luns Tee wrote:
> >> On Monday, August 1, 2022 at 6:05:56 PM UTC-7, Frank Krygowski wrote:
> >>> On 8/1/2022 3:03 PM, Tom Kunich wrote:
> >>>>
> >>>> The comments that newer aluminum alloys are not stiffer are total nonsense.
> >>> OK, show us your evidence. The property that matters is the Modulus of
> >>> Elasticity, usually abbreviated E.
> >>>
> >>> Show us an aluminum alloy that has E = 11 million psi, instead of the
> >>> typical value of 10 million to 10.3 million psi.
> >> I think there's a whole discussion of where one draws the line for whether a particular alloy can still be called an aluminum alloy, and when you need to at least hyphenate it to something else. There are aluminum-lithium alloys which are about in that neighbourhood which sometimes get referred to as just being aluminum alloys. Take Alcoa 2090-T84 for example: 76GPa (11Mpsi) modulus.
> >>
> >> I don't know for a fact whether this or similar alloys are actually used for bike components or not, but given they're 3x the cost, I doubt it. I don't even know if these alloys are used in anything other than sheet form or extrusions.
> >>
> >> But there's also the question of whether a 10% difference in modulus counts as significant or not, too. If you're squeezing hard enough that 1mm of your brake lever travel is due to flex, can you really detect if you're squeezing 9mm instead? Compare this with the difference between 49mm and 39mm reach. Call these 40 and 50. Assuming identical cross-section geometry, but otherwise scaling the paths of the brake arms accordingly, the shorter arm is 1.25^2=1.56x as stiff.
> >
> > Well consider it in terms of English measurements. The alloy those old Campy Super Record breaks had am E of 68 and the commonly use 7075 has an E of almost 72 or over 100.000 psi different.
> ??? AFAIK there is no "English" measurement of modulus of elasticity of
> aluminum alloys that gives values of 68 or 72 (times ten to any power).

I'm pretty sure sparky was talking about Luns' usage of metric units - which as I mentioned shouldn't prove to be a challenge to any legitimate engineer. I'm also convinced he is confusing other mechanical properties
Which _do_ have ratings ~70 (yield strength, tensile strength), but aren't really relevant to the conversation.

[funkma...@hotmail.com]

On Tuesday, August 2, 2022 at 1:53:33 PM UTC-4, jeff.li...@gmail.com wrote:
> On Tue, 2 Aug 2022 07:52:24 -0700 (PDT), "funkma...@hotmail.com"
> <funkma...@hotmail.com> wrote:
>
> >I think it's likely you're confusing Modulus of Elasticity with Young's Modulus.
> Young's Modulus, Modulus of Elasticity, and Elastic Modulus are the
> same, long as we're talking about tension:
> <https://www.engineeringtoolbox.com/young-modulus-d_417.html>
> <https://en.wikipedia.org/wiki/Elastic_modulus>
> Both terms are the ratio of tensile (pulling) stress to strain, or the
> slope of the curve just prior to permanent deformation (yield point).
> <https://en.wikipedia.org/wiki/Stress%E2%80%93strain_curve>
>

Yup, my brainfart - it's been a long time since I concerned my self with such issues.

[Roger Merriman]

Even today in some areas such as hill climbing which isn’t UCI control and
so bikes can be very light! With sometimes rather token brakes ie light but
not terribly effective!

> Longer arms would tend to lead to lower mechanical advantage, if other
> things were held equal. But that could have been addressed in other
> ways. I understand there are long reach dual pivots that have very
> acceptable mechanical advantage. And browsing through _The Data Book_
> will reveal dozens of unusual approaches to brake design.
>
> All these factors must work together to produce a good brake design. But
> it is certainly NOT true that the stiffness of relevant aluminum alloys
> has increased significantly.
>
> Or perhaps I should say: If Tom (hah!) or anyone else has evidence that
> there's been a big increase in the modulus of elasticity of relevant
> aluminum alloys, I'd really like to see some documentation.
>
>

Roger merriman

[Jeff Liebermann]

On Tue, 02 Aug 2022 10:28:02 -0500, AMuzi <a...@yellowjersey.org> wrote:

>On 8/2/2022 10:01 AM, funkma...@hotmail.com wrote:
>> On Tuesday, August 2, 2022 at 8:33:07 AM UTC-4, AMuzi wrote:
>>>
>>> Typical (many Campagnolo components including brake
>>> caliperss) aluminum alloy here:
>>> https://www.barate.it/en/products/alloy-2024-avional-150
>>
>> Where did you get the information that this specific 2024 alloy is the type used by Campy for their components? Tommy is claiming they use 7075.

>Campagnolo wrote Avional for years, can't find any current
>mention of alloy used:
>
>https://velobase.com/ViewComponent.aspx?ID=532fa429-4cd0-48d8-90cd-1f60ecb92a3d.

The only use of 2024 I could find was in a stem. It's mentioned here:
<https://www.albrechtcycle.com/product/paul-component-engineering-boxcar-stem-black-raw-polished-31.8-5076.htm>
but not on the vendors data sheets:
<https://www.paulcomp.com/shop/components/cockpit/boxcar-stem/>

2024 might have been called 24ST alloy.
<https://en.wikipedia.org/wiki/2024_aluminium_alloy>

Alcoa 2024 data sheet.
<https://web.archive.org/web/20060827072154/http://www.alcoa.com/mill_products/catalog/pdf/alloy2024techsheet.pdf>
Seems to be made for sheet, plate, forging, extruding but not casting.
Data sheets says 2024 is susceptible to atmospheric (probably
chlorine) corrosion which means it has to be coated with something.
Campagnolo coat their brake components. Unless I missed something,
2024 doesn't seem like it's suitable for bicycle brakes etc.

[Jeff Liebermann]

On Tue, 2 Aug 2022 11:06:19 -0700 (PDT), "funkma...@hotmail.com"

<funkma...@hotmail.com> wrote:

>On Tuesday, August 2, 2022 at 1:53:33 PM UTC-4, jeff.li...@gmail.com wrote:
>> On Tue, 2 Aug 2022 07:52:24 -0700 (PDT), "funkma...@hotmail.com"
>> <funkma...@hotmail.com> wrote:
>>
>> >I think it's likely you're confusing Modulus of Elasticity with Young's Modulus.
>> Young's Modulus, Modulus of Elasticity, and Elastic Modulus are the
>> same, long as we're talking about tension:
>> <https://www.engineeringtoolbox.com/young-modulus-d_417.html>
>> <https://en.wikipedia.org/wiki/Elastic_modulus>
>> Both terms are the ratio of tensile (pulling) stress to strain, or the
>> slope of the curve just prior to permanent deformation (yield point).
>> <https://en.wikipedia.org/wiki/Stress%E2%80%93strain_curve>

>Yup, my brainfart - it's been a long time since I concerned my self with such issues.

Not a problem. I had to look it up to be sure. In the process of
searching, I found several authoritative looking web pages wrongly
claiming that the terms were different. It took me a while to untangle
the mess. I was also distracted by reading about Tomas Young, the
inventor of Young's Modulus.
<https://en.wikipedia.org/wiki/Thomas_Young_(scientist)>
Very impressive list of abilities, studies and discoveries.

[funkma...@hotmail.com]

Andrews datasheet notes "Marine atmospheres: critical", Campy usually does some sort of hard coating, but I'd guess a few years by the beach might prove problematic regardless.

[Jeff Liebermann]

On Tue, 2 Aug 2022 12:18:23 -0700 (PDT), "funkma...@hotmail.com"

May I humbly suggest a procedure that does not require years of UV
exposure or destructive testing. See the comment by Phil Johnson at:
<https://www.finishing.com/45/74.shtml>
All you need is an ohms guesser (multimeter). If the surface is
conductive, the aluminum hasn't been anodized or alodined (chromate
conversion). If the surface is an insulator, it's coated with
something.

[John B.]

On Tue, 2 Aug 2022 08:01:52 -0700 (PDT), "funkma...@hotmail.com"
<funkma...@hotmail.com> wrote:

>On Tuesday, August 2, 2022 at 8:33:07 AM UTC-4, AMuzi wrote:
>>
>> Typical (many Campagnolo components including brake
>> caliperss) aluminum alloy here:
>> https://www.barate.it/en/products/alloy-2024-avional-150
>
>Where did you get the information that this specific 2024 alloy is the type used by Campy for their components? Tommy is claiming they use 7075.

I would ask whether 2024 is used as a casting material. From memory
(always a touch and go sort of thing) I seem to remember that even
welding 2024 and 7075 was not recommended.
--
Cheers,

John B.

[John B.]

On Tue, 2 Aug 2022 12:18:23 -0700 (PDT), "funkma...@hotmail.com"

Any aluminum alloy that contains copper is prone to corrosion.
Aircraft sheet aluminum that is made from 2024, one of the copper
bearing aluminum alloys, was coated with a very thin layer of pure
aluminum to prevent, or limit corrosion. I believe it is still
available under the trade name "Alclad".

--
Cheers,

John B.

[John B.]

On Tue, 02 Aug 2022 11:21:22 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:

The term "avional" seems to apply to a number of aluminum-copper
alloys
https://en.wikipedia.org/wiki/Duralumin#Avional

If this is the stuff that Campagnolo used then yes, it would need to
be coated or it would corrode.
--
Cheers,

John B.

[AMuzi]

Perusing Campagnolo materials in our library, 'Avional'
disappeared in the late 1990s along with the word 'forged'.
Pressure mold (thixoform) and carbon seem to have replaced
those items.

I should restate that: 'used Avional alloy at one time'.

BTW I can' think of any major parts manufacturer with a weld
on any aluminum component.

[Jeff Liebermann]

On Wed, 03 Aug 2022 07:26:02 +0700, John B. <sloc...@gmail.com>
wrote:

Welding is not a good idea because the physical characteristics of
7075 and probably 2024 are very dependent on the tempering. Get the
metal too hot during welding and the tempering and strength are lost:
<https://en.wikipedia.org/wiki/7075_aluminium_alloy#Mechanical_properties>

List of aluminum alloys suitable for casting. 2024 is not on the
list:
<https://www.alcastcompany.com/aluminum-alloys.html>
<https://www.aluminumcastingscorp.com/aluminummeltingdept.html>
and various heat treatments to be performed after casting:
<https://www.genfoundry.com/uploads/images/WCD%20-%20Images%20and%20PDFs/PDFs/alloys%20poured.pdf>

List of aluminum alloys suitable for forging. 2xxx and 7075 are on
the list:
<https://www.forgemag.com/articles/83807-forging-materials-aluminum-alloys>
<https://www.forging.org/forging/design/43-aluminum-alloys.html>

Therefore, if 2024 or 7075 were used to make bicycle brake parts, it
would be a forging process. I can't tell what level of hardening is
most common. My guess(tm) is that its probably one of the lower tech
and lower strength processes because of cost, and because even though
it's an "aerospace" alloy, a bicycle brake does not need to survive
the hostile conditions found in aircraft.

[John B.]

On Tue, 02 Aug 2022 14:08:54 -0700, Jeff Liebermann <je...@cruzio.com>
wrote:

But, but, but... the normal anti corrosion coating for 2024 aluminum
sheets used on aircraft is a coating of pure aluminum. It is called
"Alclad".
https://en.wikipedia.org/wiki/Alclad
Since 1920, already (:-)
--
Cheers,

John B.

[Luns Tee]

On Monday, August 1, 2022 at 6:03:34 PM UTC-7, Frank Krygowski wrote:
> Longer arms would tend to lead to lower mechanical advantage, if other
> things were held equal. But that could have been addressed in other
> ways. I understand there are long reach dual pivots that have very
> acceptable mechanical advantage. And browsing through _The Data Book_
> will reveal dozens of unusual approaches to brake design.

It's lower mechanical advantage if only lengthening the reach without also lengthening the arms from pivots to cable. I remember the Harris Cyclery web page at one time had a description of Shimano long-reach dual-pivot calipers which said that everything was scaled appropriately to maintain the same MA as the short-reach calipers. ISTR that the arms were also beefed up to make up for flex from the additional length, so the calipers were materially heavier than their short-reach counterparts.

I'm curious, Frank, what Data Book are you referring to?

On Monday, August 1, 2022 at 7:51:33 PM UTC-7, cycl...@gmail.com wrote:
> Well consider it in terms of English measurements. The alloy those old Campy Super Record breaks had am E of 68 and the commonly use 7075 has an E of almost 72 or over 100.000 psi different.

GPa, which your 68 and 72 are in, is not an English measurement, and a 100.000psi is less than 1% of the typical 10Mpsi of E. Also, what basis do you have for claiming the old brakes had an E of 68GPa aside from pointing out the arms flex visibly? If they flexed 4% more or 4% less, that would still be visible flex, and you have no basis for comparison to say whether the flex observed is actually more than what it might otherwise be.

The ~72GPa alloys that have been put forth so far - 7075-T6 (Ergal), 2024(Avional) - have been around for decades, certainly well before Campagnolo switched from centrepull to sidepull brakes. Again, what evidence is there that Campagnolo was not already using 72GPa alloys by then? Calipers of the time flexing only proves they chose not to make them heavier than they were.

> While Frank wants to pretend that is no difference at all, it is in fact a large difference.

Frank said nothing of the sort. What he did say, right off the bat, is they're the same within a few percent. To quote:

> So: A super-strong aluminum alloy and a much weaker aluminum alloy have
> the same stiffness, within a few percent. If a modern brake does happen
> to be stiffer than an older brake, it's not because of the composition
> of the alloy. It would have to be because of differences in design - for
> example, the shape and size of the cross sections of the relevant parts.

The numbers you put forth, 68GPa and 72GPa are both within a few percent of the 70GPa. Thank you for demonstrating exactly what Frank said, that they're the same within a few percent. The difference is hardly a large difference. A large difference in modulus would be the 3x difference between steel and aluminum alloys, or even the ~1.5x difference between aluminum and titanium.

> I consider a 4% increase in bending strength a great deal especially when combined with a redesign of the mechanical structure to put perhaps less material but with higher leverage.

Stiffness is not strength. The difference in strength between different alloys can be vastly more than 4%. Redesign of the mechanical structure as you've acknowledged, is where gains in stiffness are to be found.

>Again, Frank is pretending that Campagnolo engineers don't know what they're doing. According to him modern brakes bend as much as the old Super Record brakes.

You're again putting words into Frank's mouth; I haven't seen him say anything of the sort. Only a deliberate misreading of what he's written could twist what he's written into what you claim here.

I will put forth that the IMO, the flex that exists in old sidepull calipers is not a material limitation but exists because that's the design compromise they chose at the time - it was deliberately allowed to flex as much as they flexed. Consider that they just came off of centrepull brakes, where the force applied to each brake arm is half of the cable tension, so the brake arms from yoke to pivot were almost double the length to make up for it. Compared to the extra flex of those long arms, whatever flex the sidepulls had was already a significant improvement, and not wanting for even more stiffness at the time, they allowed it. Stiffness was not limited by the materials of the day, they could have easily made the arms even stiffer, just at the expense of extra weight. They simply didn't want the extra weight, and the stiffness was considered already good enough.

On Tuesday, August 2, 2022 at 8:28:08 AM UTC-7, AMuzi wrote:
> >> Typical (many Campagnolo components including brake
> >> caliperss) aluminum alloy here:
> >> https://www.barate.it/en/products/alloy-2024-avional-150

> Campagnolo wrote Avional for years, can't find any current
> mention of alloy used:

I believe Avional is a marketing name, and applies to more than one alloy. Predecessor to 2024 was 2017, and I believe prior to that, possibly in a different numbering system, 1917. No matter, the modulus specified by the same vendor is the same for 2017 as for 2024, and also within rounding error of the modulus for 7075-T6.

https://www.barate.it/en/products/rolled-plate-avional-100-en-aw-2017

On Tuesday, August 2, 2022 at 11:21:30 AM UTC-7, jeff.li...@gmail.com wrote:
> The only use of 2024 I could find was in a stem. It's mentioned here:
> <https://www.albrechtcycle.com/product/paul-component-engineering-boxcar-stem-black-raw-polished-31.8-5076.htm>

Ingrid appears to use it too, but only in billet form, not forged.

https://biciclista.us/products/ingrid-g-crankset?variant=13773926006847

-Luns

[John B.]

I believe that you are using too many words in your explanation. As
someone said "Brevity is generally considered a stylistic virtue as
long as it's not achieved at the expense of clarity."

If you leave out the words "about", mechanical" and "design" you will
not, in any way, alter the fundamental concept.
--
Cheers,

John B.

[AMuzi]

A treasure which belongs in any cyclist's library:

https://www.goodreads.com/book/show/1117769.100_Years_of_Bicycle_Component_and_Accessory_Design_

[Jeff Liebermann]

On Wed, 03 Aug 2022 08:11:05 +0700, John B. <sloc...@gmail.com>

Oops. I should have known that. Thanks for the correction.

My excuse is that I came from the marine radio business. All of the
radios I helped design used either Alodine 1200 (chromate conversion)
for chassis and panels or anodizing for heat sinks. The castings were
painted. The chassis parts were 6061-T6 or 5052. I don't recall what
we used for castings. Various types of stainless steel hardware.
Stainless 316 hardware (or 304 when the vendor was out of stock). At
no time did I see any AlumiPlate in our stuff or the competitors.

Dumb question: How well does a thin AlumiPlate layer work to protect
aluminum bicycle forged parts from chlorine attack if the part is
being rubbed by other parts? Various brake arms have a number of
rubbing surfaces and friction points. Does the pure aluminum
protection disappear and corrosion set in, or is there some mechanism
to prevent that from happening?

[ritzann...@gmail.com]

BB Style Square Taper
Long long long ago. Beautiful cranks.

[Jeff Liebermann]

On Tue, 02 Aug 2022 20:43:44 -0500, AMuzi <a...@yellowjersey.org> wrote:

>A treasure which belongs in any cyclist's library:
>https://www.goodreads.com/book/show/1117769.100_Years_of_Bicycle_Component_and_Accessory_Design_

Thanks. I just ordered the book from Amazon:
<https://www.amazon.com/Data-Book-Bicycle-Component-Accessory/dp/1892495791>
$34.28 including shipping and taxes.

[Tom Kunich]

I has to convert the numbers to am American system I was more familiar with. 68 was the E of the Campy materials which was used in those Super Record brakes that I found somewhere. And 7075 is 71.7 If you think that I made a mistake in the conversion then correct me. rather than say that I was wrong. This all came from that tin plated piece3 of polish shit claiming that all brakes flex the same after I showed pictures demonstrating both alloy and geometry changes in Campy brakes to eliminate flex. I agreed with you that the major difference was the geometry and Campy has continually improved on that, but tell me how Frank would ever know anything about it since his equipment was all made in 1955?

[John B.]

On Tue, 02 Aug 2022 18:49:39 -0700, Jeff Liebermann <je...@cruzio.com>

Firstly, mixing aluminum and stainless in a marine environment is a
recipe for corrosion and, at least in boat building, require some sort
of "Insulation" from each other. Somewhere I've probably still got a
can of "goop" for coating stainless screws in aluminum spars.

Secondly, I don't think that Alclad is used for bike tubes. Firstly
because if you weld Alclad you destroy the coating in the vicinity of
the weld and secondly I'm not sure that the alloy is used in bicycle
tubes is noticeably effected by atmospheric corrosion. It might be
that it doesn't corrode any more rapidly then pure aluminum.

I read that 6061 is commonly used in bicycle frames which is an
aluminum, magnesium and silicon alloy which is weldable. When welding
T-6 grade I believe that loss of strength in the heat effected areas -
near welds - is initially in the 40% region, but over time "age
hardens" and regains some of the lost strength.

The Aluminum Design Manual (Aluminum Association) recommends the
design strength of the material adjacent to the weld to be taken as
165 MPa/24000 PSI without proper heat treatment after the welding.

It would might also be possible to heat treat the finished welded
frame, but I would assume that it might require some sort of frame to
hold the welded frame in alignment during the heating and cooling
cycle.
--
Cheers,

John B.

[ritzann...@gmail.com]

Tommy, proofread your sentences. I know s and d are beside each other on the keyboard. And n and m are beside each other on the keyboard. So a simple typing mistake on your part. But you would have caught your errors if you proofread your posts. Your sentence should read "I had to convert the numbers to an American..."

> 68 was the E of the Campy materials which was used in those Super Record brakes that I found somewhere. And 7075 is 71.7 If you think that I made a mistake in the conversion then correct me. rather than say that I was wrong.

Tommy, if Luns Tee is correcting you, as he did, then you were wrong. No need to say it. If something needs correcting, then it is wrong.

> This all came from that tin plated piece3 of polish shit claiming that all brakes flex the same after I showed pictures demonstrating both alloy and geometry changes in Campy brakes to eliminate flex. I agreed with you that the major difference was the geometry and Campy has continually improved on that, but tell me how Frank would ever know anything about it since his equipment was all made in 1955?

Because Frank has seen Campagnolo brakes in person on bicycles of people he rides with. And seen them in pictures too. I don't own and I don't think I have ever even driven a diesel engine. But I do understand the concept of how diesel engines work. Pressure of the diesel and oxygen causes them to heat up and explode. Unlike gasoline engines where a spark is introduced into the chamber containing the gasoline and oxygen. Tommy, people can and do understand how things work without personally having the thing. Unlike you who has things and does not understand how they work. NASA scientists figured out how to send men and objects into space without going into space themselves.

[funkma...@hotmail.com]

As noted previously, real engineers can freely converse between the two.

> 68 was the E of the Campy materials which was used in those Super Record brakes that I found somewhere. And 7075 is 71.7

Too bad campy brakes aren't made from 7000 series alloys, as Andrew pointed out.

> If you think that I made a mistake in the conversion then correct me. rather than say that I was wrong.

He did exactly that, sparky. He didn't use the word 'wrong' or any synonyms. He very clearly corrected you.

> This all came from that tin plated piece3 of polish shit claiming that all brakes flex the same

For the 5th time in this thread, no, he didn't, and your use of ethnic invective only goes to show what a fucking low-life you are.

> after I showed pictures demonstrating both alloy and geometry changes in Campy brakes to eliminate flex.

You didn't show him any pictures which made mention of alloys, and geometry changes are _exactly_ what Frank, Luns, and every one else commenting have been telling you are the real issue.

> I agreed with you that the major difference was the geometry and Campy has continually improved on that, but tell me how Frank would ever know anything about it since his equipment was all made in 1955?

Gawd yer an idiot. Shut the fuck up tommy.

[AMuzi]

Yes, exactly, and double that for repairs which begin with
cleaning and annealing. And welding a closed figure in
aluminum with a high heat expansion rate isn't trivial
either. Which is why almost no one does aluminum bicycle
frame repair.

[Frank Krygowski]

On 8/3/2022 12:24 AM, John B. wrote:
>
>
> The Aluminum Design Manual (Aluminum Association) recommends the
> design strength of the material adjacent to the weld to be taken as
> 165 MPa/24000 PSI without proper heat treatment after the welding.
>
> It would might also be possible to heat treat the finished welded
> frame, but I would assume that it might require some sort of frame to
> hold the welded frame in alignment during the heating and cooling
> cycle.

FWIW, our 1986 Cannondales are 6061-T6, IIRC. They were TIG welded, then
the entire frame was solution heat treated after welding.

The nice thing about the solution heat treat of aluminum alloys is that
after the quench, the part is quite soft and ductile - the opposite of
what happens when quenching steel to heat treat it. The aluminum gains
strength and hardness afterwards during "aging" (either natural or
"artificial" at slightly elevated temperatures).

Cannondale was able to take the freshly quenched frames and place them
in fixtures to bend the tubes around so the critical points - especially
head tube, bottom bracket and rear dropouts - were perfectly aligned. On
some early Cannondale frames, the tubes were slightly but visibly
crooked; but the alignment of critical points was correct.

--
- Frank Krygowski

[AMuzi]

+1

[Luns Tee]

On Tuesday, August 2, 2022 at 6:43:51 PM UTC-7, AMuzi wrote:
> On 8/2/2022 8:12 PM, Luns Tee wrote:
> > On Monday, August 1, 2022 at 6:03:34 PM UTC-7, Frank Krygowski wrote:
> >> Longer arms would tend to lead to lower mechanical advantage, if other
> >> things were held equal. But that could have been addressed in other
> >> ways. I understand there are long reach dual pivots that have very
> >> acceptable mechanical advantage. And browsing through _The Data Book_
> >> will reveal dozens of unusual approaches to brake design.
> >

> > I'm curious, Frank, what Data Book are you referring to?

> A treasure which belongs in any cyclist's library:
>
> https://www.goodreads.com/book/show/1117769.100_Years_of_Bicycle_Component_and_Accessory_Design_
> --
> Andrew Muzi
> <www.yellowjersey.org/>
> Open every day since 1 April, 1971

Nice! I've known of the publisher from Frank Berto's book, _The Dancing Chain_ and _The Sunset of Suntour_, but somehow never heard of this one. Just ordered a copy - thanks!

-Luns

[John B.]

Welding anything :-0

I once saw a project to build a large flat welded steel "floor". The
welding shop laid down two 4' x 8' sheets of, about 1/4" flat, steel
and the Shop Chief told the welder the "just tack it every foot or
so". The welder, a young bloke, apparently thought that the old shop
chief didn't know what he was talking about laid the two sheets flat,
about 1/8" apart and started welding that 8' joint.... I think he got
about a foot before he had to quit (:-)
--
Cheers,

John B.

[ritzann...@gmail.com]

It is humorous that Tommy, who has described himself as some sort of immigrant from an east European Mongol tribe and the Caucasus mountains, thinks Polish are bad and deserving of ridicule. Odd perspective out Tommy boy has.

[ritzann...@gmail.com]

Not being a welder I cannot speak to the technical matters. However, I once bought a aluminum pickup truck box. Those silver ones that go across the bed behind the cab. It was too deep. So I cut the bottom 6 inches off. Bought a new sheet of aluminum for a bottom. My brother welded it onto the bottom of the cut truck box. Continuous weld. No heat treating and everything is not perfectly straight and smooth. But it works and is the right depth now.

[John B.]

I wasn't there and I didn't watch but I doubt very much that your
brother laid a, what would it be? four by two foot slab of aluminum?
down and started welding from one end.

I'm guessing, but I'll bet that he did just what the old Shop Chief
told the youngster - tack it every foot or so.

(and when you get that done Then weld it)
--
Cheers,

John B.

[Frank Krygowski]

Every once in a while, I take that book down just to browse through it. I appreciate the art as well as the ingenuity
it documents.

- Frank Krygowski

[Frank Krygowski]

I'm not an expert welder, more of a hacker. But I agree about doing the tack weld first.
Otherwise I'd expect the new bottom piece would badly distort as it was being welded.

Something as stout as a big aluminum tool box would probably have enough structural
strength to not be much distorted by the residual stresses from the weld. But I think the tacking
would be needed to hold the bottom in place as the continuous welds were completed.

And the finished product would almost certainly have plenty of residual stresses locked in.
They wouldn't matter for this toolbox, but they would for highly stressed structures like bike frames.

- Frank Krygowski

[Tom Kunich]

I just set up the brakes on my Moser. I'll bet that there wasn't anything I didn't do wrong and I've been down in the garage all day to get to the point of needing nothing more than handlebar tape. Finally. The Basso was supposed to be delivered today but it wasn't loaded on the truck so it won't come until tomorrow. So I'll take the Moser out for a ride tomorrow.

Apparently someone took the left hand Record lever apart and since I've never worked on these before it took me three house of fiddling around to figure out how to preload the spring. Turns out to be very easy once you know how to do it. Everything is working great now.

[Jeff Liebermann]

On Wed, 3 Aug 2022 17:18:25 -0700 (PDT), "russell...@yahoo.com"
<ritzann...@gmail.com> wrote:

>It is humorous that Tommy, who has described himself as some sort of immigrant from an east European Mongol tribe and the Caucasus mountains, thinks Polish are bad and deserving of ridicule. Odd perspective out Tommy boy has.

Tom probably doesn't like the Polish because Frank and I have some
Polish ancestry.

If it hadn't been for WWI, the Polish cavalry would have overrun
Europe and eventually ruled the world.

[Jeff Liebermann]

On Wed, 3 Aug 2022 20:15:19 -0700 (PDT), Tom Kunich
<cycl...@gmail.com> wrote:

>I'll bet that there wasn't anything I didn't do wrong...

You might want to rephrase that, unless you really do want to declare
that you did everything wrong.

[Luns Tee]

On Wednesday, August 3, 2022 at 5:36:18 PM UTC-7, John B. wrote:
> I'm guessing, but I'll bet that he did just what the old Shop Chief
> told the youngster - tack it every foot or so.
>
> (and when you get that done Then weld it)

I imagine it's pretty much universal practice that tacks are laid down linearly, starting from one end and going to the other, as is the final weld.

I've never heard of anybody doing the following , but I like the idea of laying down tacks following Hofmeister's rule from Phyllotaxy. For anyone who doesn't recognize the name, basically think of how a sunflower or pinecone places its seeds as it grows. The idea here is just placing tack welds instead of seeds.

Basically tack both ends of the final weld. From that point on, count up starting from n=1 and place the n'th weld at L*frac(n*phi) from the starting end, where L is the overall length (distance between the initial two welds) and phi is the golden ratio. Just keep going until the tacks all fuse together to cover the entire length to be welded. There's no particular magic number for the final n. Each new tack weld goes into a section with the currently largest tack-to-neighbouring-tack distance, and the distances get smaller as you progress, always being at most a factor of phi^2 ~= 2.62 between largest and shortest remaining distances.

I believe this would give the most uniform possible heating of the length of the weld for the least possible residual stress, and doesn't leave any obvious starting or stopping point of the weld. It would also be very confusing for a human doing the welding, though I think it still possible with some kind of computer assistance. It's probably best done by a CNC spot welder. This would go particularly well with a rotary weld positioner, though it would be very slow compared to conventional usage.

-Luns

[AMuzi]

Yes, that's right.

[Frank Krygowski]

On 8/3/2022 11:56 PM, Jeff Liebermann wrote:
> On Wed, 3 Aug 2022 20:15:19 -0700 (PDT), Tom Kunich
> <cycl...@gmail.com> wrote:
>
>> I'll bet that there wasn't anything I didn't do wrong...
>
> You might want to rephrase that, unless you really do want to declare
> that you did everything wrong.

I just assumed Tom was finally confessing.


--
- Frank Krygowski

[Frank Krygowski]

Until you got to your final paragraph, I was thinking of the Venn
diagram showing the set of welders, and the set of people who understand
what you wrote. I figure the intersection of those sets is pretty tiny.

And I also thought, "For me, starting the weld is the tricky part.
That's a lot of weld starts!"

But I guess the strategy might make some sense in some situations for
automatic welds, such as robot welding.

--
- Frank Krygowski

[Jeff Liebermann]

I didn't assume that Tom was not serious.
<https://en.wikipedia.org/wiki/Double_negative>

[Ralph Barone]

I would probably use a binary search algorithm here. On the first pass, put
down tack welds at 0 and 100%. Second pass, 50%. Third pass 25 and 75%.
Fourth pass 12.5, 37.5, 62.5 and 87.5%.
Basically on each successive pass, you drop a tack midway between two
previous tacks. At some point you call it a day and fill in between them.

Fibonacci is cool, but I’m not a big fan of any practical process that
involves calculations containing irrational numbers.

[ritzann...@gmail.com]

I do not recall exactly how the welding went. I was there but memory 30 years later. My comment about "continuous weld" was about there being one long line of weld all along the bottom of the box and the new bottom plate. Not about whether it was done at one end and went 5 feet to the other side non stop. If I remember I will look at the weld and see if I can figure out if there were stops and starts in the weld bead. If he did intermittent welding all along the edges.

[John B.]

On Thu, 4 Aug 2022 12:39:04 -0700 (PDT), "russell...@yahoo.com"

I'm not sure what you are trying to say? I would assume that when you
talk about welding a new "bottom" on a box that there was, when
completed a complete weld "all the way around", if only to keep the
water out (:-0

My discussion was on the technique to get that "all the way around"
without undue problems.
--
Cheers,

John B.

[ritzann...@gmail.com]

Right. And my reply was that I do not recall how the all the way around weld got there. I do not recall if my brother used the tack welding technique. An inch weld at 200 different spots. Or if he started on one end and did a weld all the way down to the other end. I'm guessing he did a whole lot of short welds. But I do not specifically remember.