Cannondale recall

On Monday, July 29, 2019 at 7:34:02 AM UTC-7, AMuzi wrote:
On 7/29/2019 9:26 AM, Tom Kunich wrote:
On Saturday, July 27, 2019 at 7:58:49 PM UTC-7, Frank Krygowski wrote:
On Saturday, July 27, 2019 at 8:09:58 PM UTC-4, Tom Kunich wrote:


OK Frank - as an engineer tell us about the weaknesses of solid objects with bending forces on them.

Sure. What do you want to know?

You can look up "Stress = M * c / I" to begin your home study. Let me know what
questions you have.

- Frank Krygowski

Just curious why you didn't want to go into the fact that a solid round will bend before a hollow tube of the same diameter.


That's not true for steel bar vs tube. Else prybars would be
hollow!

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

I think what I was getting at is that a tube is MUCH stiffer for its weight than a solid rod. But it is not stronger since a rod contains more material.

On Monday, July 29, 2019 at 8:19:58 AM UTC-7, Frank Krygowski wrote:
On Monday, July 29, 2019 at 10:26:26 AM UTC-4, Tom Kunich wrote:
On Saturday, July 27, 2019 at 7:58:49 PM UTC-7, Frank Krygowski wrote:
On Saturday, July 27, 2019 at 8:09:58 PM UTC-4, Tom Kunich wrote:


OK Frank - as an engineer tell us about the weaknesses of solid objects with bending forces on them.

Sure. What do you want to know?

You can look up "Stress = M * c / I" to begin your home study. Let me know what
questions you have.

- Frank Krygowski

Just curious why you didn't want to go into the fact that a solid round will bend before a hollow tube of the same diameter.

sigh Tom, I force myself to not respond to a _lot_ of your mistakes. But
that one gets no pass. If you're talking about the same material in both cases
and all other things being equal, you're simply wrong. You shouldn't need any
science background at all to recognize that it's nonsense.

- Frank Krygowski

What you TRY to be is the biggest ass you can possibly be and you usually succeed. As is usual you imply that bicycles should be made out of solid rod.

On Sunday, July 28, 2019 at 7:44:15 PM UTC-4, sms wrote:
On 7/28/2019 10:06 AM, Tosspot wrote:
On 27/07/2019 20:19, Frank Krygowski wrote:

snip

The trouble with Rivendell forks is they are still hollow. Can you
imagine? A hole right up the middle! We need to return to the solid
forks of yore.

Frank has it spot on.Â* If only they'd go through the simple p[process of
turning the fork inside out, moving the hole to the outside where it
would cause less trouble, we wouldn't be having these recalls.

Actually a hollow fork will be stronger than a solid fork.

nope.


A hollow tube is stronger than a rod of equal mass (assuming the same
material).

Of equal mass, yes. Of the same diameter, no. That's why crowbars don't need to be much larger than an inch in diameter.

As the inside diameter increases the tube becomes stronger.
You can increase the diameter to compensate for a weaker material. This
is why aluminum frame tubes have to be of greater diameter than steel
frame tubes.

That only works up to a point. There's a ratio of the wall thickness to diameter before the strength starts to decrease.


Surprised that Frank would not know about this since it is basic physics
and material science.

He does, you're confusing things.

On Monday, July 29, 2019 at 1:13:52 PM UTC-7, Zen Cycle wrote:
On Sunday, July 28, 2019 at 7:44:15 PM UTC-4, sms wrote:
On 7/28/2019 10:06 AM, Tosspot wrote:
On 27/07/2019 20:19, Frank Krygowski wrote:

snip

The trouble with Rivendell forks is they are still hollow. Can you
imagine? A hole right up the middle! We need to return to the solid
forks of yore.

Frank has it spot on.Â* If only they'd go through the simple p[process of
turning the fork inside out, moving the hole to the outside where it
would cause less trouble, we wouldn't be having these recalls.

Actually a hollow fork will be stronger than a solid fork.

nope.


A hollow tube is stronger than a rod of equal mass (assuming the same
material).

Of equal mass, yes. Of the same diameter, no. That's why crowbars don't need to be much larger than an inch in diameter.

As the inside diameter increases the tube becomes stronger.
You can increase the diameter to compensate for a weaker material. This
is why aluminum frame tubes have to be of greater diameter than steel
frame tubes.

That only works up to a point. There's a ratio of the wall thickness to diameter before the strength starts to decrease.


Surprised that Frank would not know about this since it is basic physics
and material science.

He does, you're confusing things.

I think that perhaps you're confusing things. A crowbar can be MUCH larger than 1" in diameter and they can also be made of hollow tubes and are. What you're confusing is that you have limited strength and hence a crowbar only needs to have the strength that you cannot exceed.

I'm not familiar with stock car racing anymore but it used to be when you pulled into the pits for a tire change they wheeled these long levers under front and back and lifted the entire car off of its wheels front and back with simple leverage - a crow bar. Those tubes were 3" in diameter.

On 7/29/2019 11:53 AM, Tom Kunich wrote:
On Monday, July 29, 2019 at 7:34:02 AM UTC-7, AMuzi wrote:
On 7/29/2019 9:26 AM, Tom Kunich wrote:
On Saturday, July 27, 2019 at 7:58:49 PM UTC-7, Frank Krygowski wrote:
On Saturday, July 27, 2019 at 8:09:58 PM UTC-4, Tom Kunich wrote:


OK Frank - as an engineer tell us about the weaknesses of solid objects with bending forces on them.

Sure. What do you want to know?

You can look up "Stress = M * c / I" to begin your home study. Let me know what
questions you have.

- Frank Krygowski

Just curious why you didn't want to go into the fact that a solid round will bend before a hollow tube of the same diameter.


That's not true for steel bar vs tube. Else prybars would be
hollow!

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

I think what I was getting at is that a tube is MUCH stiffer for its weight than a solid rod. But it is not stronger since a rod contains more material.

OK, you're a little less wrong now. But only a little.

Tom, you'd do well to stick to what you know. If you want to branch out,
do the required reading.


--
- Frank Krygowski

On Monday, July 29, 2019 at 7:54:50 PM UTC-7, Frank Krygowski wrote:
On 7/29/2019 11:53 AM, Tom Kunich wrote:
On Monday, July 29, 2019 at 7:34:02 AM UTC-7, AMuzi wrote:
On 7/29/2019 9:26 AM, Tom Kunich wrote:
On Saturday, July 27, 2019 at 7:58:49 PM UTC-7, Frank Krygowski wrote:
On Saturday, July 27, 2019 at 8:09:58 PM UTC-4, Tom Kunich wrote:


OK Frank - as an engineer tell us about the weaknesses of solid objects with bending forces on them.

Sure. What do you want to know?

You can look up "Stress = M * c / I" to begin your home study. Let me know what
questions you have.

- Frank Krygowski

Just curious why you didn't want to go into the fact that a solid round will bend before a hollow tube of the same diameter.


That's not true for steel bar vs tube. Else prybars would be
hollow!

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

I think what I was getting at is that a tube is MUCH stiffer for its weight than a solid rod. But it is not stronger since a rod contains more material.

OK, you're a little less wrong now. But only a little.

Tom, you'd do well to stick to what you know. If you want to branch out,
do the required reading.


--
- Frank Krygowski

You might want to do the required thinking but there's little to no chance of that.