Are KMC-Z chains directional?

On 3/3/21 8:00 PM, jbeattie wrote:
On Wednesday, March 3, 2021 at 6:16:56 PM UTC-8, wrote:
On Wed, 3 Mar 2021 15:47:52 -0800, Joerg
wrote:
My last Shimano chain is worn so I'll be trying the first KMC-Z72
8-speed chain on my road bike next week, since Jay recommended those.
Are they directional? The package doesn't say and the Internet doesn't
either.
This article doesn't mention KMC, but does mention that SRAM chains
are not directional, while some Shimano chains are directional. The
article suggests that directional chains have the logo stamped only on
one side of the chain, which should be facing away from the frame:

Are Bicycle Chains directional?
https://bikesfaq.com/are-bicycle-chains-directional-some-are-some-arent

I couldn't find a data sheet on the KMC Z-72. Everywhere I look, all
I find are "discontinued" or "otto stock" (except some old stock on
eBay).

KMC chains are not directional, and I doubt that even Shimano makes direction 8sp chains. Its a marketing ploy for the high end groups, IMO.


It probably would cost 0.01% in top speed if mounted in reverse so I'd
arrive in Sacramento a few seconds late :-)


I went out and looked at my own Shimano chain -- which is directional -- and I mounted it in the right direction, except for the quick link. I wasn't watching the arrow, which is pointing in the wrong direction -- and probably accounts for my slowness.


That happened to me on the rear tire. I was listening to something
interesting on the AM radio in the garage and just when the tire was all
mounted and pumped up ... rats! The sipes now point backwards. Oh well.

--
Regards, Joerg

http://www.analogconsultants.com/

On 3/4/2021 11:45 AM, Tom Kunich wrote:
On Wednesday, March 3, 2021 at 9:01:39 PM UTC-8, AMuzi wrote:
On 3/3/2021 6:21 PM, John B. wrote:
On Wed, 3 Mar 2021 15:47:52 -0800, Joerg
wrote:

My last Shimano chain is worn so I'll be trying the first KMC-Z72
8-speed chain on my road bike next week, since Jay recommended those.
Are they directional? The package doesn't say and the Internet doesn't
either.

I don't think that roller chains are directional, are they?

Some designs, yes.

Frank is the mechanical engineer. You'd think that he might have something to say about this rather than he far left comments about discrimination where none ever existed.

What do you need to hear? The chain question's been answered. If you
want to talk about the mechanical details of asymmetrical chains, start
it off. Maybe I'll add something. It's not rocket science.

--
- Frank Krygowski

On Thursday, March 4, 2021 at 1:53:09 PM UTC-5, Frank Krygowski wrote:
On 3/4/2021 11:45 AM, Tom Kunich wrote:
On Wednesday, March 3, 2021 at 9:01:39 PM UTC-8, AMuzi wrote:
On 3/3/2021 6:21 PM, John B. wrote:
On Wed, 3 Mar 2021 15:47:52 -0800, Joerg
wrote:

My last Shimano chain is worn so I'll be trying the first KMC-Z72
8-speed chain on my road bike next week, since Jay recommended those.
Are they directional? The package doesn't say and the Internet doesn't
either.

I don't think that roller chains are directional, are they?

Some designs, yes.

Frank is the mechanical engineer. You'd think that he might have something to say about this rather than he far left comments about discrimination where none ever existed.
What do you need to hear?

He needs to hear that you acquiesce to his superior knowledge and experience in all things, including - but not limited to:
- bicycle frame building and design
- bicycle riding and fitness
- Bicycle componentry design, installation, and maintenance
- metallurgy
- electronic hardware design
- software and design
- sociology
- physics
- biology
- education
- history
- religion
- political science
- law
- and anything else

In other words, Frank, don't feed the troll.

On 4/3/21 1:16 pm, Jeff Liebermann wrote:
On Wed, 3 Mar 2021 15:47:52 -0800, Joerg
wrote:

My last Shimano chain is worn so I'll be trying the first KMC-Z72
8-speed chain on my road bike next week, since Jay recommended those.
Are they directional? The package doesn't say and the Internet doesn't
either.

This article doesn't mention KMC, but does mention that SRAM chains
are not directional, while some Shimano chains are directional. The
article suggests that directional chains have the logo stamped only on
one side of the chain, which should be facing away from the frame:

Are Bicycle Chains directional?
https://bikesfaq.com/are-bicycle-chains-directional-some-are-some-arent

I couldn't find a data sheet on the KMC Z-72. Everywhere I look, all
I find are "discontinued" or "otto stock" (except some old stock on
eBay).


According to that web page;

"What happens if you put it on the wrong way?

It does not impact brand new chains’ performance if you do inadvertently
put the chain in the “wrong� direction. Perhaps on really high-end
chains and groupsets, it may have a marginal impact on efficiency or
lifespan; however, for most cyclists, you will not notice any drop in
performance or skipping of gears.

If you are taking off an existing chain to clean it and put it back on,
you must put it back in the same direction as it was before.

Due to wear and tear, failure to replace the chain how it was before
will result in the chain and gears slipping."


Does anyone know why they think that the chain and gears might slip as
described in the last sentence?

--
JS

On 3/4/2021 3:15 PM, James wrote:
On 4/3/21 1:16 pm, Jeff Liebermann wrote:
On Wed, 3 Mar 2021 15:47:52 -0800, Joerg

wrote:

My last Shimano chain is worn so I'll be trying the first
KMC-Z72
8-speed chain on my road bike next week, since Jay
recommended those.
Are they directional? The package doesn't say and the
Internet doesn't
either.

This article doesn't mention KMC, but does mention that
SRAM chains
are not directional, while some Shimano chains are
directional. The
article suggests that directional chains have the logo
stamped only on
one side of the chain, which should be facing away from
the frame:

Are Bicycle Chains directional?
https://bikesfaq.com/are-bicycle-chains-directional-some-are-some-arent


I couldn't find a data sheet on the KMC Z-72. Everywhere
I look, all
I find are "discontinued" or "otto stock" (except some old
stock on
eBay).


According to that web page;

"What happens if you put it on the wrong way?

It does not impact brand new chains’ performance if you do
inadvertently put the chain in the “wrong� direction.
Perhaps on really high-end chains and groupsets, it may have
a marginal impact on efficiency or lifespan; however, for
most cyclists, you will not notice any drop in performance
or skipping of gears.

If you are taking off an existing chain to clean it and put
it back on, you must put it back in the same direction as it
was before.

Due to wear and tear, failure to replace the chain how it
was before will result in the chain and gears slipping."


Does anyone know why they think that the chain and gears
might slip as described in the last sentence?


Chain wear is between rivet and roller. Presumably rivets
wear on the front side while rollers roll.

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

On 3/4/2021 4:00 PM, AMuzi wrote:
On 3/4/2021 3:15 PM, James wrote:
On 4/3/21 1:16 pm, Jeff Liebermann wrote:
On Wed, 3 Mar 2021 15:47:52 -0800, Joerg

wrote:

My last Shimano chain is worn so I'll be trying the first
KMC-Z72
8-speed chain on my road bike next week, since Jay
recommended those.
Are they directional? The package doesn't say and the
Internet doesn't
either.

This article doesn't mention KMC, but does mention that
SRAM chains
are not directional, while some Shimano chains are
directional. The
article suggests that directional chains have the logo
stamped only on
one side of the chain, which should be facing away from
the frame:

Are Bicycle Chains directional?
https://bikesfaq.com/are-bicycle-chains-directional-some-are-some-arent



I couldn't find a data sheet on the KMC Z-72. Everywhere
I look, all
I find are "discontinued" or "otto stock" (except some old
stock on
eBay).


According to that web page;

"What happens if you put it on the wrong way?

It does not impact brand new chains’ performance if you do
inadvertently put the chain in the “wrong� direction.
Perhaps on really high-end chains and groupsets, it may have
a marginal impact on efficiency or lifespan; however, for
most cyclists, you will not notice any drop in performance
or skipping of gears.

If you are taking off an existing chain to clean it and put
it back on, you must put it back in the same direction as it
was before.

Due to wear and tear, failure to replace the chain how it
was before will result in the chain and gears slipping."


Does anyone know why they think that the chain and gears
might slip as described in the last sentence?


Chain wear is between rivet and roller. Presumably rivets
wear on the front side while rollers roll.


Whoops. Rivet is driven so wear would be on the back side
not front. Sorry.

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

On 5/3/21 9:02 am, AMuzi wrote:
On 3/4/2021 4:00 PM, AMuzi wrote:
On 3/4/2021 3:15 PM, James wrote:
On 4/3/21 1:16 pm, Jeff Liebermann wrote:
On Wed, 3 Mar 2021 15:47:52 -0800, Joerg

wrote:

My last Shimano chain is worn so I'll be trying the first
KMC-Z72
8-speed chain on my road bike next week, since Jay
recommended those.
Are they directional? The package doesn't say and the
Internet doesn't
either.

This article doesn't mention KMC, but does mention that
SRAM chains
are not directional, while some Shimano chains are
directional.* The
article suggests that directional chains have the logo
stamped only on
one side of the chain, which should be facing away from
the frame:

Are Bicycle Chains directional?
https://bikesfaq.com/are-bicycle-chains-directional-some-are-some-arent




I couldn't find a data sheet on the KMC Z-72.* Everywhere
I look, all
I find are "discontinued" or "otto stock" (except some old
stock on
eBay).


According to that web page;

"What happens if you put it on the wrong way?

It does not impact brand new chains’ performance if you do
inadvertently put the chain in the “wrong� direction.
Perhaps on really high-end chains and groupsets, it may have
a marginal impact on efficiency or lifespan; however, for
most cyclists, you will not notice any drop in performance
or skipping of gears.

If you are taking off an existing chain to clean it and put
it back on, you must put it back in the same direction as it
was before.

Due to wear and tear, failure to replace the chain how it
was before will result in the chain and gears slipping."


Does anyone know why they think that the chain and gears
might slip as described in the last sentence?


Chain wear is between rivet and roller. Presumably rivets
wear on the front side while rollers roll.


Whoops. Rivet is driven so wear would be on the back side not front. Sorry.


Looking at a section of Campagnolo chain and assuming KMC Z 72 chains
are constructed similarly, the pin doesn't touch the roller. The chain
acts in tension whether it is upside down or right side up, so the pin
wear against the inner plates is always the same. Because the roller
can roll right around, how does it know which way is up? Chain
elongation happens as the pins and inner plates wear, and measures the
same regardless of whether you stand on your head or not.

Clearly I still do not understand the reason.

--
JS

On 3/4/21 3:16 PM, James wrote:
On 5/3/21 9:02 am, AMuzi wrote:
On 3/4/2021 4:00 PM, AMuzi wrote:
On 3/4/2021 3:15 PM, James wrote:
On 4/3/21 1:16 pm, Jeff Liebermann wrote:
On Wed, 3 Mar 2021 15:47:52 -0800, Joerg

wrote:

My last Shimano chain is worn so I'll be trying the first
KMC-Z72
8-speed chain on my road bike next week, since Jay
recommended those.
Are they directional? The package doesn't say and the
Internet doesn't
either.

This article doesn't mention KMC, but does mention that
SRAM chains
are not directional, while some Shimano chains are
directional.* The
article suggests that directional chains have the logo
stamped only on
one side of the chain, which should be facing away from
the frame:

Are Bicycle Chains directional?
https://bikesfaq.com/are-bicycle-chains-directional-some-are-some-arent




I couldn't find a data sheet on the KMC Z-72.* Everywhere
I look, all
I find are "discontinued" or "otto stock" (except some old
stock on
eBay).


According to that web page;

"What happens if you put it on the wrong way?

It does not impact brand new chains’ performance if you do
inadvertently put the chain in the “wrong� direction.
Perhaps on really high-end chains and groupsets, it may have
a marginal impact on efficiency or lifespan; however, for
most cyclists, you will not notice any drop in performance
or skipping of gears.

If you are taking off an existing chain to clean it and put
it back on, you must put it back in the same direction as it
was before.

Due to wear and tear, failure to replace the chain how it
was before will result in the chain and gears slipping."


Does anyone know why they think that the chain and gears
might slip as described in the last sentence?


Chain wear is between rivet and roller. Presumably rivets
wear on the front side while rollers roll.


Whoops. Rivet is driven so wear would be on the back side not front.
Sorry.


Looking at a section of Campagnolo chain and assuming KMC Z 72 chains
are constructed similarly, the pin doesn't touch the roller.


AFAICT the rollers run on the bushings.

https://en.wikipedia.org/wiki/Bicycl...h_numbers).png

...* The chain
acts in tension whether it is upside down or right side up, so the pin
wear against the inner plates is always the same.* Because the roller
can roll right around, how does it know which way is up?* Chain
elongation happens as the pins and inner plates wear, and measures the
same regardless of whether you stand on your head or not.

Clearly I still do not understand the reason.


When you pedal the bushings wear off in riding direction (front) because
that's where the friction between roller and pin happens. After a while
the bushings aren't perfectly round anymore. The pins won't be either
because there is friction between bushing and pin.

I assume that when you mount a partly worn chain in reverse direction
from how it was original now the wear starts happening at the unused
surface area of the pins and bushings. That can result in a different
"seating" of the rollers in the also somewhat worn sprockets and
potential skipping.

Anyhow, I wish bicycle parts would have a longer lifespan in terms of
miles. My rear tires are gone at 1500mi, chains at 2500mi, cassettes at
5000mi and the BB doesn't live much longer either. That's a sad state of
affairs IMO, especially for people like me who clock more miles on their
bicycles than in their cars.

--
Regards, Joerg

http://www.analogconsultants.com/

On Thursday, March 4, 2021 at 3:50:56 PM UTC-8, Joerg wrote:
On 3/4/21 3:16 PM, James wrote:
On 5/3/21 9:02 am, AMuzi wrote:
On 3/4/2021 4:00 PM, AMuzi wrote:
On 3/4/2021 3:15 PM, James wrote:
On 4/3/21 1:16 pm, Jeff Liebermann wrote:
On Wed, 3 Mar 2021 15:47:52 -0800, Joerg

wrote:

My last Shimano chain is worn so I'll be trying the first
KMC-Z72
8-speed chain on my road bike next week, since Jay
recommended those.
Are they directional? The package doesn't say and the
Internet doesn't
either.

This article doesn't mention KMC, but does mention that
SRAM chains
are not directional, while some Shimano chains are
directional. The
article suggests that directional chains have the logo
stamped only on
one side of the chain, which should be facing away from
the frame:

Are Bicycle Chains directional?
https://bikesfaq.com/are-bicycle-chains-directional-some-are-some-arent




I couldn't find a data sheet on the KMC Z-72. Everywhere
I look, all
I find are "discontinued" or "otto stock" (except some old
stock on
eBay).


According to that web page;

"What happens if you put it on the wrong way?

It does not impact brand new chains’ performance if you do
inadvertently put the chain in the “wrong†direction.
Perhaps on really high-end chains and groupsets, it may have
a marginal impact on efficiency or lifespan; however, for
most cyclists, you will not notice any drop in performance
or skipping of gears.

If you are taking off an existing chain to clean it and put
it back on, you must put it back in the same direction as it
was before.

Due to wear and tear, failure to replace the chain how it
was before will result in the chain and gears slipping."


Does anyone know why they think that the chain and gears
might slip as described in the last sentence?


Chain wear is between rivet and roller. Presumably rivets
wear on the front side while rollers roll.


Whoops. Rivet is driven so wear would be on the back side not front.
Sorry.


Looking at a section of Campagnolo chain and assuming KMC Z 72 chains
are constructed similarly, the pin doesn't touch the roller.
AFAICT the rollers run on the bushings.

https://en.wikipedia.org/wiki/Bicycl...h_numbers).png

... The chain
acts in tension whether it is upside down or right side up, so the pin
wear against the inner plates is always the same. Because the roller
can roll right around, how does it know which way is up? Chain
elongation happens as the pins and inner plates wear, and measures the
same regardless of whether you stand on your head or not.

Clearly I still do not understand the reason.

When you pedal the bushings wear off in riding direction (front) because
that's where the friction between roller and pin happens. After a while
the bushings aren't perfectly round anymore. The pins won't be either
because there is friction between bushing and pin.

I assume that when you mount a partly worn chain in reverse direction
from how it was original now the wear starts happening at the unused
surface area of the pins and bushings. That can result in a different
"seating" of the rollers in the also somewhat worn sprockets and
potential skipping.

Anyhow, I wish bicycle parts would have a longer lifespan in terms of
miles. My rear tires are gone at 1500mi, chains at 2500mi, cassettes at
5000mi and the BB doesn't live much longer either. That's a sad state of
affairs IMO, especially for people like me who clock more miles on their
bicycles than in their cars.
--
Regards, Joerg

http://www.analogconsultants.com/

IGH and a track chain/cog. That should do the trick. Go with solid rubber tires. I don't know what to tell you about the BB. Maybe a sintered bushing design.

-- Jay Beattie.

On 3/4/2021 6:16 PM, James wrote:
On 5/3/21 9:02 am, AMuzi wrote:
On 3/4/2021 4:00 PM, AMuzi wrote:
On 3/4/2021 3:15 PM, James wrote:
On 4/3/21 1:16 pm, Jeff Liebermann wrote:
On Wed, 3 Mar 2021 15:47:52 -0800, Joerg

wrote:

My last Shimano chain is worn so I'll be trying the first
KMC-Z72
8-speed chain on my road bike next week, since Jay
recommended those.
Are they directional? The package doesn't say and the
Internet doesn't
either.

This article doesn't mention KMC, but does mention that
SRAM chains
are not directional, while some Shimano chains are
directional.* The
article suggests that directional chains have the logo
stamped only on
one side of the chain, which should be facing away from
the frame:

Are Bicycle Chains directional?
https://bikesfaq.com/are-bicycle-chains-directional-some-are-some-arent




I couldn't find a data sheet on the KMC Z-72.* Everywhere
I look, all
I find are "discontinued" or "otto stock" (except some old
stock on
eBay).


According to that web page;

"What happens if you put it on the wrong way?

It does not impact brand new chains’ performance if you do
inadvertently put the chain in the “wrong� direction.
Perhaps on really high-end chains and groupsets, it may have
a marginal impact on efficiency or lifespan; however, for
most cyclists, you will not notice any drop in performance
or skipping of gears.

If you are taking off an existing chain to clean it and put
it back on, you must put it back in the same direction as it
was before.

Due to wear and tear, failure to replace the chain how it
was before will result in the chain and gears slipping."


Does anyone know why they think that the chain and gears
might slip as described in the last sentence?


Chain wear is between rivet and roller. Presumably rivets
wear on the front side while rollers roll.


Whoops. Rivet is driven so wear would be on the back side not front.
Sorry.


Looking at a section of Campagnolo chain and assuming KMC Z 72 chains
are constructed similarly, the pin doesn't touch the roller.* The chain
acts in tension whether it is upside down or right side up, so the pin
wear against the inner plates is always the same.* Because the roller
can roll right around, how does it know which way is up?* Chain
elongation happens as the pins and inner plates wear, and measures the
same regardless of whether you stand on your head or not.

Clearly I still do not understand the reason.

I don't know for sure, but I suspect the problem is this: The wear on
the chain's internals is not symmetrical. It mostly occurs as the chain
leaves a small rear cog. The tension puts loads on the surfaces as each
chain link pivots from bent to straight.

That pivoting is always in the same direction, so the wear is primarily
on the mating surfaces below the centerline of the taut upper chain -
that is, toward the center of the chain's loop. The portions of the pin
and (integral) bushing above the centerline wear much less. And as the
chain wears, it tends to wear the cog teeth to match its gradually
longer pitch.

If you change the chain orientation, you're exposing new portions of
those internal surfaces to wear. Since they haven't yet worn as much,
the effective pitch is less at the moments the links are on the cog.
That gives a pitch mismatch that causes the skipping.

That's my guess.

A corollary might be that flipping a non-directional chain from time to
time might might extend the life of the chain and cogs, somewhat similar
to alternating two or three chains on the same cogs. But I'll never be
curious enough to bother trying that.

--
- Frank Krygowski