Chain suck sucks -- frame protectors

On Wednesday, February 3, 2021 at 10:00:44 AM UTC-8, Frank Krygowski wrote:
On 2/3/2021 3:55 AM, Jeff Liebermann wrote:
On Tue, 2 Feb 2021 22:15:38 -0500, Frank Krygowski
wrote:

On 2/2/2021 9:56 PM, Jeff Liebermann wrote:

2. Maybe there's something that can be done to the drive train to
reduce the tendency for the chain to fall off. Maybe tightening the
springs in the rear derailleur?

I'm curious about the details of chain suck. I don't know exactly how it
happens. Can anyone explain?

Jay posted a link to a good video on how to fix chain suck. Here's
another that shows a quick fix:
https://www.youtube.com/watch?v=KQkmnQ6z304
However, you didn't ask how to fix it. You asked how it happens.

What's happening is that the trailing (low tension) part of the chain,
between the chainring and the rear derailleur, is not releasing from
the chainring. This part of the chain continues to rotate along with
the chainring and eventually hits the front derailleur, where it jams
the drive train.

The basic problem is either:
1. Something is holding the chain onto the chainring (gear hook,
dirty chain)
2. There is not enough stripping force provided by the rear
derailleur to peel the chain away from the chainring (weak rear spring
derailleur, excessively long chain).
3. A badly timed shift is releasing the tension on the trailing low
tension section of chain, which reduces the chain stripping force
sufficiently that the chain sticks to the chainring.

This video shows it quite well:
"Chain suck - with no load applied [0049]"
https://www.youtube.com/watch?v=IRP_jlNr7Z0 (0:38)

Once the failure mechanism is identified, one can then make a decision
on how to deal with the problem.

More videos on chain suck:
https://www.youtube.com/results?search_query=chain+suck

For additional entertainment value, try lubricating the chain with
chainsaw bar oil. There are quite a few articles from riders claiming
that this fixes chain suck and other problems. I'm skeptical and
don't understand how it works:
https://www.google.com/search?q=bicycle+chain+lube+with+chainsaw+bar+oil+ suck

Disclaimer: I are not an expert on bicycle chain suck but do know a
few things about chainsaws.
Thanks, that helps.

In Jay's and your videos, the failure to release the chain occurred on
sprocket teeth maybe 30(?) degrees in front of the crank. I wonder how
consistent that is. If it is, I wonder if modifying a couple teeth would
allow easier release.

Those teeth probably get highly loaded (they're at the top when the
other crank arm is in "power position") so the working face of the tooth
would need to be intact, but maybe the back (unloaded) side could be
modified.

The actual problem encountered by my son was kind of a hybrid of dropped chain and chain suck, probably caused by shifting under load and maybe a maladjusted FD, but it was no problem for me and fine on the stand.

-- Jay Beattie.

On Wednesday, February 3, 2021 at 1:39:17 p.m. UTC-5, jbeattie wrote:
On Wednesday, February 3, 2021 at 10:00:44 AM UTC-8, Frank Krygowski wrote:
On 2/3/2021 3:55 AM, Jeff Liebermann wrote:
On Tue, 2 Feb 2021 22:15:38 -0500, Frank Krygowski
wrote:

On 2/2/2021 9:56 PM, Jeff Liebermann wrote:

2. Maybe there's something that can be done to the drive train to
reduce the tendency for the chain to fall off. Maybe tightening the
springs in the rear derailleur?

I'm curious about the details of chain suck. I don't know exactly how it
happens. Can anyone explain?

Jay posted a link to a good video on how to fix chain suck. Here's
another that shows a quick fix:
https://www.youtube.com/watch?v=KQkmnQ6z304
However, you didn't ask how to fix it. You asked how it happens.

What's happening is that the trailing (low tension) part of the chain,
between the chainring and the rear derailleur, is not releasing from
the chainring. This part of the chain continues to rotate along with
the chainring and eventually hits the front derailleur, where it jams
the drive train.

The basic problem is either:
1. Something is holding the chain onto the chainring (gear hook,
dirty chain)
2. There is not enough stripping force provided by the rear
derailleur to peel the chain away from the chainring (weak rear spring
derailleur, excessively long chain).
3. A badly timed shift is releasing the tension on the trailing low
tension section of chain, which reduces the chain stripping force
sufficiently that the chain sticks to the chainring.

This video shows it quite well:
"Chain suck - with no load applied [0049]"
https://www.youtube.com/watch?v=IRP_jlNr7Z0 (0:38)

Once the failure mechanism is identified, one can then make a decision
on how to deal with the problem.

More videos on chain suck:
https://www.youtube.com/results?search_query=chain+suck

For additional entertainment value, try lubricating the chain with
chainsaw bar oil. There are quite a few articles from riders claiming
that this fixes chain suck and other problems. I'm skeptical and
don't understand how it works:
https://www.google.com/search?q=bicycle+chain+lube+with+chainsaw+bar+oil+ suck

Disclaimer: I are not an expert on bicycle chain suck but do know a
few things about chainsaws.
Thanks, that helps.

In Jay's and your videos, the failure to release the chain occurred on
sprocket teeth maybe 30(?) degrees in front of the crank. I wonder how
consistent that is. If it is, I wonder if modifying a couple teeth would
allow easier release.

Those teeth probably get highly loaded (they're at the top when the
other crank arm is in "power position") so the working face of the tooth
would need to be intact, but maybe the back (unloaded) side could be
modified.
The actual problem encountered by my son was kind of a hybrid of dropped chain and chain suck, probably caused by shifting under load and maybe a maladjusted FD, but it was no problem for me and fine on the stand.

-- Jay Beattie.

Isn't this the type of problem that the newer clutch-type rear derailleurs were designed to stop?

Cheers

On Wed, 3 Feb 2021 11:10:58 -0800 (PST), Sir Ridesalot
wrote:

Isn't this the type of problem that the newer clutch-type rear derailleurs were designed to stop?
Cheers

Yes.

The idea is to maintain the tension on the chain between the
chainwheel and rear derailleur. That should help prevent chain suck
if the chain is "glued" to the chainwheel by mud or crud. However, I
doubt it would provide sufficient tension to force the chain away from
a chainwheel that has hooked teeth. Also, notice that as the
chainwheel rotates past the point where the chain is expected to
release from the chainwheel, the holding force of a hooked tooth
increases. By the time the chain reaches the tail end of the front
derailleur, it's effectively locked in place by the hooked teeth. This
is probably why we don't see some kind of chain stripper attached to
the trailing end of the front derailleur. It would be really
difficult to provide enough rearward force on the chain to tear it
away from hooked teeth.

Full disclosu I've played with clutch type rear derailleurs on
other people's bicycles but have not tried one on mine. Not enough
experience with these to be certain that I haven't missed something.
Someone with more experience should be able to give a better answer.


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

On Wednesday, February 3, 2021 at 1:32:20 PM UTC-8, wrote:
On Wed, 3 Feb 2021 11:10:58 -0800 (PST), Sir Ridesalot
wrote:

Isn't this the type of problem that the newer clutch-type rear derailleurs were designed to stop?
Cheers
Yes.

The idea is to maintain the tension on the chain between the
chainwheel and rear derailleur. That should help prevent chain suck
if the chain is "glued" to the chainwheel by mud or crud. However, I
doubt it would provide sufficient tension to force the chain away from
a chainwheel that has hooked teeth. Also, notice that as the
chainwheel rotates past the point where the chain is expected to
release from the chainwheel, the holding force of a hooked tooth
increases. By the time the chain reaches the tail end of the front
derailleur, it's effectively locked in place by the hooked teeth. This
is probably why we don't see some kind of chain stripper attached to
the trailing end of the front derailleur. It would be really
difficult to provide enough rearward force on the chain to tear it
away from hooked teeth.

Full disclosu I've played with clutch type rear derailleurs on
other people's bicycles but have not tried one on mine. Not enough
experience with these to be certain that I haven't missed something.
Someone with more experience should be able to give a better answer.

I haven't seen that term used before. What is the difference between the modern derailleur and the older type?

On Wed, 3 Feb 2021 13:47:32 -0800 (PST), Tom Kunich
wrote:

On Wednesday, February 3, 2021 at 1:32:20 PM UTC-8, wrote:
On Wed, 3 Feb 2021 11:10:58 -0800 (PST), Sir Ridesalot
wrote:

Isn't this the type of problem that the newer clutch-type rear derailleurs were designed to stop?
Cheers
Yes.

The idea is to maintain the tension on the chain between the
chainwheel and rear derailleur. That should help prevent chain suck
if the chain is "glued" to the chainwheel by mud or crud. However, I
doubt it would provide sufficient tension to force the chain away from
a chainwheel that has hooked teeth. Also, notice that as the
chainwheel rotates past the point where the chain is expected to
release from the chainwheel, the holding force of a hooked tooth
increases. By the time the chain reaches the tail end of the front
derailleur, it's effectively locked in place by the hooked teeth. This
is probably why we don't see some kind of chain stripper attached to
the trailing end of the front derailleur. It would be really
difficult to provide enough rearward force on the chain to tear it
away from hooked teeth.

Full disclosu I've played with clutch type rear derailleurs on
other people's bicycles but have not tried one on mine. Not enough
experience with these to be certain that I haven't missed something.
Someone with more experience should be able to give a better answer.

I haven't seen that term used before. What is the difference between the modern derailleur and the older type?

The difference between modern and older is one year or greater.
According to the dates on the relevant YouTube videos, the clutch
derailleurs started appearing about 4 years ago. I haven't been
paying attention and was informed that they exist a few weeks ago.

Google search finds a substantial number of articles on the topic,
along with a substantial number of opinions.
https://www.google.com/search?q=clutch+type+rear+derailleur
https://www.youtube.com/results?search_query=clutch+derailleur
I'm lacking in experience with clutch type rear derailleurs and
therefore can only refer you to the available articles and to suggest
you ask those with more experience.

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

Op donderdag 4 februari 2021 om 04:51:14 UTC+1 schreef :
On Wed, 3 Feb 2021 13:47:32 -0800 (PST), Tom Kunich
wrote:

On Wednesday, February 3, 2021 at 1:32:20 PM UTC-8, wrote:
On Wed, 3 Feb 2021 11:10:58 -0800 (PST), Sir Ridesalot
wrote:

Isn't this the type of problem that the newer clutch-type rear derailleurs were designed to stop?
Cheers
Yes.

The idea is to maintain the tension on the chain between the
chainwheel and rear derailleur. That should help prevent chain suck
if the chain is "glued" to the chainwheel by mud or crud. However, I
doubt it would provide sufficient tension to force the chain away from
a chainwheel that has hooked teeth. Also, notice that as the
chainwheel rotates past the point where the chain is expected to
release from the chainwheel, the holding force of a hooked tooth
increases. By the time the chain reaches the tail end of the front
derailleur, it's effectively locked in place by the hooked teeth. This
is probably why we don't see some kind of chain stripper attached to
the trailing end of the front derailleur. It would be really
difficult to provide enough rearward force on the chain to tear it
away from hooked teeth.

Full disclosu I've played with clutch type rear derailleurs on
other people's bicycles but have not tried one on mine. Not enough
experience with these to be certain that I haven't missed something.
Someone with more experience should be able to give a better answer.

I haven't seen that term used before. What is the difference between the modern derailleur and the older type?
The difference between modern and older is one year or greater.
According to the dates on the relevant YouTube videos, the clutch
derailleurs started appearing about 4 years ago. I haven't been
paying attention and was informed that they exist a few weeks ago.

Google search finds a substantial number of articles on the topic,
along with a substantial number of opinions.
https://www.google.com/search?q=clutch+type+rear+derailleur
https://www.youtube.com/results?search_query=clutch+derailleur
I'm lacking in experience with clutch type rear derailleurs and
therefore can only refer you to the available articles and to suggest
you ask those with more experience.
--
Jeff Liebermann
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558


I have on my gravel bike a GRX RD with a clutch. It is meant to prevent excessive slapping of the lower part of the chain on bumpy terrain. It works quite well. There is a downside: shifting is a little harder which is not a problem with Di2 but noticeable with a mechanical RD. You can turn the cluch on and off. There are two types off clutches ; one that just add rotational friction to the derailleur cage. The more 'intelligent' add viscous damping to the movement of the derailleur cage. This is speed dependent and doesn't affect the slow shifing viscous as much.

Lou

On Wednesday, February 3, 2021 at 7:51:14 PM UTC-8, wrote:
On Wed, 3 Feb 2021 13:47:32 -0800 (PST), Tom Kunich
wrote:

On Wednesday, February 3, 2021 at 1:32:20 PM UTC-8, wrote:
On Wed, 3 Feb 2021 11:10:58 -0800 (PST), Sir Ridesalot
wrote:

Isn't this the type of problem that the newer clutch-type rear derailleurs were designed to stop?
Cheers
Yes.

The idea is to maintain the tension on the chain between the
chainwheel and rear derailleur. That should help prevent chain suck
if the chain is "glued" to the chainwheel by mud or crud. However, I
doubt it would provide sufficient tension to force the chain away from
a chainwheel that has hooked teeth. Also, notice that as the
chainwheel rotates past the point where the chain is expected to
release from the chainwheel, the holding force of a hooked tooth
increases. By the time the chain reaches the tail end of the front
derailleur, it's effectively locked in place by the hooked teeth. This
is probably why we don't see some kind of chain stripper attached to
the trailing end of the front derailleur. It would be really
difficult to provide enough rearward force on the chain to tear it
away from hooked teeth.

Full disclosu I've played with clutch type rear derailleurs on
other people's bicycles but have not tried one on mine. Not enough
experience with these to be certain that I haven't missed something.
Someone with more experience should be able to give a better answer.

I haven't seen that term used before. What is the difference between the modern derailleur and the older type?
The difference between modern and older is one year or greater.
According to the dates on the relevant YouTube videos, the clutch
derailleurs started appearing about 4 years ago. I haven't been
paying attention and was informed that they exist a few weeks ago.

Google search finds a substantial number of articles on the topic,
along with a substantial number of opinions.
https://www.google.com/search?q=clutch+type+rear+derailleur
https://www.youtube.com/results?search_query=clutch+derailleur
I'm lacking in experience with clutch type rear derailleurs and
therefore can only refer you to the available articles and to suggest
you ask those with more experience.
--
Jeff Liebermann
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558
I wouldn't call that a clutch. I'd call it a derailleur arm ratchet mechanism to maintain high pressure on the arm only in one direction.

On Thursday, February 4, 2021 at 12:02:22 AM UTC-8, wrote:
Op donderdag 4 februari 2021 om 04:51:14 UTC+1 schreef :
On Wed, 3 Feb 2021 13:47:32 -0800 (PST), Tom Kunich
wrote:

On Wednesday, February 3, 2021 at 1:32:20 PM UTC-8, wrote:
On Wed, 3 Feb 2021 11:10:58 -0800 (PST), Sir Ridesalot
wrote:

Isn't this the type of problem that the newer clutch-type rear derailleurs were designed to stop?
Cheers
Yes.

The idea is to maintain the tension on the chain between the
chainwheel and rear derailleur. That should help prevent chain suck
if the chain is "glued" to the chainwheel by mud or crud. However, I
doubt it would provide sufficient tension to force the chain away from
a chainwheel that has hooked teeth. Also, notice that as the
chainwheel rotates past the point where the chain is expected to
release from the chainwheel, the holding force of a hooked tooth
increases. By the time the chain reaches the tail end of the front
derailleur, it's effectively locked in place by the hooked teeth. This
is probably why we don't see some kind of chain stripper attached to
the trailing end of the front derailleur. It would be really
difficult to provide enough rearward force on the chain to tear it
away from hooked teeth.

Full disclosu I've played with clutch type rear derailleurs on
other people's bicycles but have not tried one on mine. Not enough
experience with these to be certain that I haven't missed something.
Someone with more experience should be able to give a better answer.

I haven't seen that term used before. What is the difference between the modern derailleur and the older type?
The difference between modern and older is one year or greater.
According to the dates on the relevant YouTube videos, the clutch
derailleurs started appearing about 4 years ago. I haven't been
paying attention and was informed that they exist a few weeks ago.

Google search finds a substantial number of articles on the topic,
along with a substantial number of opinions.
https://www.google.com/search?q=clutch+type+rear+derailleur
https://www.youtube.com/results?search_query=clutch+derailleur
I'm lacking in experience with clutch type rear derailleurs and
therefore can only refer you to the available articles and to suggest
you ask those with more experience.
--
Jeff Liebermann
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558
I have on my gravel bike a GRX RD with a clutch. It is meant to prevent excessive slapping of the lower part of the chain on bumpy terrain. It works quite well. There is a downside: shifting is a little harder which is not a problem with Di2 but noticeable with a mechanical RD. You can turn the cluch on and off. There are two types off clutches ; one that just add rotational friction to the derailleur cage. The more 'intelligent' add viscous damping to the movement of the derailleur cage. This is speed dependent and doesn't affect the slow shifing viscous as much.

Lou
I just bought a Felt F55X aluminum gravel bike and the group I have sitting around for it has an XT derailleur with a clutch mechanism on it. So I guess I'm a "modern man" anyway.

On 2/4/2021 11:23 AM, Tom Kunich wrote:
On Wednesday, February 3, 2021 at 7:51:14 PM UTC-8, wrote:
On Wed, 3 Feb 2021 13:47:32 -0800 (PST), Tom Kunich
wrote:

On Wednesday, February 3, 2021 at 1:32:20 PM UTC-8, wrote:
On Wed, 3 Feb 2021 11:10:58 -0800 (PST), Sir Ridesalot
wrote:

Isn't this the type of problem that the newer clutch-type rear derailleurs were designed to stop?
Cheers
Yes.

The idea is to maintain the tension on the chain between the
chainwheel and rear derailleur. That should help prevent chain suck
if the chain is "glued" to the chainwheel by mud or crud. However, I
doubt it would provide sufficient tension to force the chain away from
a chainwheel that has hooked teeth. Also, notice that as the
chainwheel rotates past the point where the chain is expected to
release from the chainwheel, the holding force of a hooked tooth
increases. By the time the chain reaches the tail end of the front
derailleur, it's effectively locked in place by the hooked teeth. This
is probably why we don't see some kind of chain stripper attached to
the trailing end of the front derailleur. It would be really
difficult to provide enough rearward force on the chain to tear it
away from hooked teeth.

Full disclosu I've played with clutch type rear derailleurs on
other people's bicycles but have not tried one on mine. Not enough
experience with these to be certain that I haven't missed something.
Someone with more experience should be able to give a better answer.

I haven't seen that term used before. What is the difference between the modern derailleur and the older type?
The difference between modern and older is one year or greater.
According to the dates on the relevant YouTube videos, the clutch
derailleurs started appearing about 4 years ago. I haven't been
paying attention and was informed that they exist a few weeks ago.

Google search finds a substantial number of articles on the topic,
along with a substantial number of opinions.
https://www.google.com/search?q=clutch+type+rear+derailleur
https://www.youtube.com/results?search_query=clutch+derailleur
I'm lacking in experience with clutch type rear derailleurs and
therefore can only refer you to the available articles and to suggest
you ask those with more experience.
--
Jeff Liebermann
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558
I wouldn't call that a clutch. I'd call it a derailleur arm ratchet mechanism to maintain high pressure on the arm only in one direction.


I wouldn't either but Shimano does so it's a 'clutch'.

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

Op donderdag 4 februari 2021 om 21:05:55 UTC+1 schreef AMuzi:
On 2/4/2021 11:23 AM, Tom Kunich wrote:
On Wednesday, February 3, 2021 at 7:51:14 PM UTC-8, wrote:
On Wed, 3 Feb 2021 13:47:32 -0800 (PST), Tom Kunich
wrote:

On Wednesday, February 3, 2021 at 1:32:20 PM UTC-8, wrote:
On Wed, 3 Feb 2021 11:10:58 -0800 (PST), Sir Ridesalot
wrote:

Isn't this the type of problem that the newer clutch-type rear derailleurs were designed to stop?
Cheers
Yes.

The idea is to maintain the tension on the chain between the
chainwheel and rear derailleur. That should help prevent chain suck
if the chain is "glued" to the chainwheel by mud or crud. However, I
doubt it would provide sufficient tension to force the chain away from
a chainwheel that has hooked teeth. Also, notice that as the
chainwheel rotates past the point where the chain is expected to
release from the chainwheel, the holding force of a hooked tooth
increases. By the time the chain reaches the tail end of the front
derailleur, it's effectively locked in place by the hooked teeth. This
is probably why we don't see some kind of chain stripper attached to
the trailing end of the front derailleur. It would be really
difficult to provide enough rearward force on the chain to tear it
away from hooked teeth.

Full disclosu I've played with clutch type rear derailleurs on
other people's bicycles but have not tried one on mine. Not enough
experience with these to be certain that I haven't missed something.
Someone with more experience should be able to give a better answer.

I haven't seen that term used before. What is the difference between the modern derailleur and the older type?
The difference between modern and older is one year or greater.
According to the dates on the relevant YouTube videos, the clutch
derailleurs started appearing about 4 years ago. I haven't been
paying attention and was informed that they exist a few weeks ago.

Google search finds a substantial number of articles on the topic,
along with a substantial number of opinions.
https://www.google.com/search?q=clutch+type+rear+derailleur
https://www.youtube.com/results?search_query=clutch+derailleur
I'm lacking in experience with clutch type rear derailleurs and
therefore can only refer you to the available articles and to suggest
you ask those with more experience.
--
Jeff Liebermann
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558
I wouldn't call that a clutch. I'd call it a derailleur arm ratchet mechanism to maintain high pressure on the arm only in one direction.

I wouldn't either but Shimano does so it's a 'clutch'.

We call it an overload clutch or torque limiter.

Lou