Rear derailliuer limit screwa.

On Tue, 28 May 2013 17:31:50 +0100, Ian Field wrote:

snip


I did some work on the gear cable early on, but I don't recall adjusting
the stop screws - it seemed to adjust OK just by setting the cable
right.

No!!! You want to adjust the limit screws BEFORE you put in the cable.
That's easy for the outer (high) limit. It's also easy for the inner
(low) limit by pushing on the derailleur body. An alternate is to set the
outer limit, and put in the cable. Then pull on the bare cable to move
the derailleur all the way inward.

You want the derailleur by itself to guarantee that it will always be on
the rear cluster. You don't want to depend on shifter stops.

"Stephen Bauman" wrote in message
...
On Tue, 28 May 2013 17:31:50 +0100, Ian Field wrote:

snip


I did some work on the gear cable early on, but I don't recall adjusting
the stop screws - it seemed to adjust OK just by setting the cable
right.

No!!! You want to adjust the limit screws BEFORE you put in the cable.
That's easy for the outer (high) limit. It's also easy for the inner
(low) limit by pushing on the derailleur body. An alternate is to set the
outer limit, and put in the cable. Then pull on the bare cable to move
the derailleur all the way inward.

You want the derailleur by itself to guarantee that it will always be on
the rear cluster. You don't want to depend on shifter stops.


Back then I was well aware to not mess with things I hadn't yet learned
about unless I had no choice.

On May 28, 5:31*pm, "Ian Field"
wrote:
"Stephen Bauman" wrote in message

...









On Tue, 28 May 2013 13:28:16 +0100, Ian Field wrote:

Have the limit screws been known to go out of adjustment all by
themselves?

As a firm believer of "if it aint broke don't fix it" I haven't touched
the limit screws since I scrounged the bike on freecycle a couple of
years ago -
its only in the past week or so the chain started jumping over the
biggest sprocket and attacking the spokes.

When I set about adjusting the limit screws, I got the impression that
they weren't even in play!

The screws don't appear to have much friction, so I'm wondering how long
they might stay set?

Let's assume that the limit screw was properly adjusted.

The limit screw would stop the derailleur from pushing the chain into the
spokes, regardless of the cable tension adjustment. Furthermore, it's
unlikely that the limit screws would vibrate loose under normal use.

A more likely scenario is that the bike fell on the derailleur. The
result is that the hanger or dropout was bent slightly inward. This means
that the previous inward limit is now closer to the wheel. It also means
that all the index positions are now off slightly.

You can usually check the dropout/hanger alignment by eye. You can
usually bend it back into a vertical position by inserting an allen key
into the derailleur and using it for leverage. There's also a shop tool
you can use to set measure and set the dropout/hanger.

On one occasion the derailleur cage actually snagged the spokes as the
binding chain pulled it toward the wheel, once I unsnagged it I just pulled
it until it looked about right - by pure dumb luck it was just about right!

Since then I've set the limit screws - I got the impression they weren't
screwed in enough to actually be doing anything, and there seemed to be
little or no friction on the screws. My question was pretty much about
whether they're likely to have gone out of adjustment all by themselves.

Not ever noticed it with the derailleurs I've used, any closeness to
spokes has been caused by whacking the derailleur mount in a crash,
collecting a polythene bag in the chain or wear of the parallelogram
pivots. The last was subtle and only really affected a lean of the
mechanism, not it's function or risk of fouling spokes.

I remember that Suntour had adjusting setscrews with a ridge of
plastic so making absolutely sure that the setscrews would not budge
under vibration. If yours does not have this or strong springs under
the set-screws then use boiled linseed oil, threadlock, paint or nail
varnish to lock them (by filling the thread). If the design of the
mech allows it, chuck the screw and bend the tag or whatever to be the
limit stop. I did this with a steel Huret at both ends after
witnessing a fall during a sprint after a chain fell between sprocket
and frame-end.

The bike was scrounged on freecycle, it was obvious it had been on the back
garden a while, and gradually became apparent that the previous owner didn't
have much of a clue about adjusting things.

I did some work on the gear cable early on, but I don't recall adjusting the
stop screws - it seemed to adjust OK just by setting the cable right.

"thirty-six" wrote in message
...
On May 28, 5:31 pm, "Ian Field"
wrote:
"Stephen Bauman" wrote in message

...









On Tue, 28 May 2013 13:28:16 +0100, Ian Field wrote:

Have the limit screws been known to go out of adjustment all by
themselves?

As a firm believer of "if it aint broke don't fix it" I haven't
touched
the limit screws since I scrounged the bike on freecycle a couple of
years ago -
its only in the past week or so the chain started jumping over the
biggest sprocket and attacking the spokes.

When I set about adjusting the limit screws, I got the impression that
they weren't even in play!

The screws don't appear to have much friction, so I'm wondering how
long
they might stay set?

Let's assume that the limit screw was properly adjusted.

The limit screw would stop the derailleur from pushing the chain into
the
spokes, regardless of the cable tension adjustment. Furthermore, it's
unlikely that the limit screws would vibrate loose under normal use.

A more likely scenario is that the bike fell on the derailleur. The
result is that the hanger or dropout was bent slightly inward. This
means
that the previous inward limit is now closer to the wheel. It also
means
that all the index positions are now off slightly.

You can usually check the dropout/hanger alignment by eye. You can
usually bend it back into a vertical position by inserting an allen key
into the derailleur and using it for leverage. There's also a shop tool
you can use to set measure and set the dropout/hanger.

On one occasion the derailleur cage actually snagged the spokes as the
binding chain pulled it toward the wheel, once I unsnagged it I just
pulled
it until it looked about right - by pure dumb luck it was just about
right!

Since then I've set the limit screws - I got the impression they weren't
screwed in enough to actually be doing anything, and there seemed to be
little or no friction on the screws. My question was pretty much about
whether they're likely to have gone out of adjustment all by themselves.

Not ever noticed it with the derailleurs I've used, any closeness to
spokes has been caused by whacking the derailleur mount in a crash,
collecting a polythene bag in the chain or wear of the parallelogram
pivots. The last was subtle and only really affected a lean of the
mechanism, not it's function or risk of fouling spokes.

I remember that Suntour had adjusting setscrews with a ridge of
plastic so making absolutely sure that the setscrews would not budge
under vibration. If yours does not have this or strong springs under
the set-screws then use boiled linseed oil, threadlock, paint or nail
varnish to lock them

ISTR a tube of Loctite flange sealant in the shed somewhere - it never sets
completely but comes out the tube fairly runny and becomes tacky over a few
days.

AFAICR the only thread lock I have is the permanent stuff that would destroy
things before coming undone.

On May 28, 7:16*pm, "Ian Field"
wrote:
"thirty-six" wrote in message

...









On May 28, 5:31 pm, "Ian Field"
wrote:
"Stephen Bauman" wrote in message

et...

On Tue, 28 May 2013 13:28:16 +0100, Ian Field wrote:

Have the limit screws been known to go out of adjustment all by
themselves?

As a firm believer of "if it aint broke don't fix it" I haven't
touched
the limit screws since I scrounged the bike on freecycle a couple of
years ago -
its only in the past week or so the chain started jumping over the
biggest sprocket and attacking the spokes.

When I set about adjusting the limit screws, I got the impression that
they weren't even in play!

The screws don't appear to have much friction, so I'm wondering how
long
they might stay set?

Let's assume that the limit screw was properly adjusted.

The limit screw would stop the derailleur from pushing the chain into
the
spokes, regardless of the cable tension adjustment. Furthermore, it's
unlikely that the limit screws would vibrate loose under normal use.

A more likely scenario is that the bike fell on the derailleur. The
result is that the hanger or dropout was bent slightly inward. This
means
that the previous inward limit is now closer to the wheel. It also
means
that all the index positions are now off slightly.

You can usually check the dropout/hanger alignment by eye. You can
usually bend it back into a vertical position by inserting an allen key
into the derailleur and using it for leverage. There's also a shop tool
you can use to set measure and set the dropout/hanger.

On one occasion the derailleur cage actually snagged the spokes as the
binding chain pulled it toward the wheel, once I unsnagged it I just
pulled
it until it looked about right - by pure dumb luck it was just about
right!

Since then I've set the limit screws - I got the impression they weren't
screwed in enough to actually be doing anything, and there seemed to be
little or no friction on the screws. My question was pretty much about
whether they're likely to have gone out of adjustment all by themselves.

Not ever noticed it with the derailleurs I've used, any closeness to
spokes has been caused by whacking the derailleur mount in a crash,
collecting a polythene bag in the chain or wear of the parallelogram
pivots. * The last was subtle and only really affected a lean of the
mechanism, not it's function or risk of fouling spokes.

I remember that Suntour had adjusting setscrews with a ridge of
plastic so making absolutely sure that the setscrews would not budge
under vibration. * If yours does not have this or strong springs under
the set-screws then use boiled linseed oil, threadlock, paint or nail
varnish to lock them

ISTR a tube of Loctite flange sealant in the shed somewhere - it never sets
completely but comes out the tube fairly runny and becomes tacky over a few
days.

AFAICR the only thread lock I have is the permanent stuff that would destroy
things before coming undone.

If that worries you, use your pink nail varnish.

"thirty-six" wrote in message
...
On May 28, 7:16 pm, "Ian Field"
wrote:
"thirty-six" wrote in message

...









On May 28, 5:31 pm, "Ian Field"
wrote:
"Stephen Bauman" wrote in message

et...

On Tue, 28 May 2013 13:28:16 +0100, Ian Field wrote:

Have the limit screws been known to go out of adjustment all by
themselves?

As a firm believer of "if it aint broke don't fix it" I haven't
touched
the limit screws since I scrounged the bike on freecycle a couple
of
years ago -
its only in the past week or so the chain started jumping over the
biggest sprocket and attacking the spokes.

When I set about adjusting the limit screws, I got the impression
that
they weren't even in play!

The screws don't appear to have much friction, so I'm wondering how
long
they might stay set?

Let's assume that the limit screw was properly adjusted.

The limit screw would stop the derailleur from pushing the chain
into
the
spokes, regardless of the cable tension adjustment. Furthermore,
it's
unlikely that the limit screws would vibrate loose under normal use.

A more likely scenario is that the bike fell on the derailleur. The
result is that the hanger or dropout was bent slightly inward. This
means
that the previous inward limit is now closer to the wheel. It also
means
that all the index positions are now off slightly.

You can usually check the dropout/hanger alignment by eye. You can
usually bend it back into a vertical position by inserting an allen
key
into the derailleur and using it for leverage. There's also a shop
tool
you can use to set measure and set the dropout/hanger.

On one occasion the derailleur cage actually snagged the spokes as the
binding chain pulled it toward the wheel, once I unsnagged it I just
pulled
it until it looked about right - by pure dumb luck it was just about
right!

Since then I've set the limit screws - I got the impression they
weren't
screwed in enough to actually be doing anything, and there seemed to
be
little or no friction on the screws. My question was pretty much about
whether they're likely to have gone out of adjustment all by
themselves.

Not ever noticed it with the derailleurs I've used, any closeness to
spokes has been caused by whacking the derailleur mount in a crash,
collecting a polythene bag in the chain or wear of the parallelogram
pivots. The last was subtle and only really affected a lean of the
mechanism, not it's function or risk of fouling spokes.

I remember that Suntour had adjusting setscrews with a ridge of
plastic so making absolutely sure that the setscrews would not budge
under vibration. If yours does not have this or strong springs under
the set-screws then use boiled linseed oil, threadlock, paint or nail
varnish to lock them

ISTR a tube of Loctite flange sealant in the shed somewhere - it never
sets
completely but comes out the tube fairly runny and becomes tacky over a
few
days.

AFAICR the only thread lock I have is the permanent stuff that would
destroy
things before coming undone.

If that worries you, use your pink nail varnish.

Funnily enough, I've got some of that for sealing the adjustment of
presettable components in my electronics projects.

On May 28, 7:54*pm, "Ian Field"
wrote:
"thirty-six" wrote in message

...









On May 28, 7:16 pm, "Ian Field"
wrote:
"thirty-six" wrote in message

....

On May 28, 5:31 pm, "Ian Field"
wrote:
"Stephen Bauman" wrote in message

et...

On Tue, 28 May 2013 13:28:16 +0100, Ian Field wrote:

Have the limit screws been known to go out of adjustment all by
themselves?

As a firm believer of "if it aint broke don't fix it" I haven't
touched
the limit screws since I scrounged the bike on freecycle a couple
of
years ago -
its only in the past week or so the chain started jumping over the
biggest sprocket and attacking the spokes.

When I set about adjusting the limit screws, I got the impression
that
they weren't even in play!

The screws don't appear to have much friction, so I'm wondering how
long
they might stay set?

Let's assume that the limit screw was properly adjusted.

The limit screw would stop the derailleur from pushing the chain
into
the
spokes, regardless of the cable tension adjustment. Furthermore,
it's
unlikely that the limit screws would vibrate loose under normal use.

A more likely scenario is that the bike fell on the derailleur. The
result is that the hanger or dropout was bent slightly inward. This
means
that the previous inward limit is now closer to the wheel. It also
means
that all the index positions are now off slightly.

You can usually check the dropout/hanger alignment by eye. You can
usually bend it back into a vertical position by inserting an allen
key
into the derailleur and using it for leverage. There's also a shop
tool
you can use to set measure and set the dropout/hanger.

On one occasion the derailleur cage actually snagged the spokes as the
binding chain pulled it toward the wheel, once I unsnagged it I just
pulled
it until it looked about right - by pure dumb luck it was just about
right!

Since then I've set the limit screws - I got the impression they
weren't
screwed in enough to actually be doing anything, and there seemed to
be
little or no friction on the screws. My question was pretty much about
whether they're likely to have gone out of adjustment all by
themselves.

Not ever noticed it with the derailleurs I've used, any closeness to
spokes has been caused by whacking the derailleur mount in a crash,
collecting a polythene bag in the chain or wear of the parallelogram
pivots. * The last was subtle and only really affected a lean of the
mechanism, not it's function or risk of fouling spokes.

I remember that Suntour had adjusting setscrews with a ridge of
plastic so making absolutely sure that the setscrews would not budge
under vibration. * If yours does not have this or strong springs under
the set-screws then use boiled linseed oil, threadlock, paint or nail
varnish to lock them

ISTR a tube of Loctite flange sealant in the shed somewhere - it never
sets
completely but comes out the tube fairly runny and becomes tacky over a
few
days.

AFAICR the only thread lock I have is the permanent stuff that would
destroy
things before coming undone.

If that worries you, use your pink nail varnish.

Funnily enough, I've got some of that for sealing the adjustment of
presettable components in my electronics projects.

As long as the screw is degreased first wiih IPA or acetone, it will
stick fast on metals.

On 5/28/2013 11:54 AM, Stephen Bauman wrote:
On Tue, 28 May 2013 17:31:50 +0100, Ian Field wrote:

snip


I did some work on the gear cable early on, but I don't recall adjusting
the stop screws - it seemed to adjust OK just by setting the cable
right.

No!!! You want to adjust the limit screws BEFORE you put in the cable.
That's easy for the outer (high) limit. It's also easy for the inner
(low) limit by pushing on the derailleur body. An alternate is to set the
outer limit, and put in the cable. Then pull on the bare cable to move
the derailleur all the way inward.

You want the derailleur by itself to guarantee that it will always be on
the rear cluster. You don't want to depend on shifter stops.


+1

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

"thirty-six" wrote in message
...
On May 28, 7:54 pm, "Ian Field"
wrote:
"thirty-six" wrote in message

...









On May 28, 7:16 pm, "Ian Field"
wrote:
"thirty-six" wrote in message

...

On May 28, 5:31 pm, "Ian Field"
wrote:
"Stephen Bauman" wrote in message

et...

On Tue, 28 May 2013 13:28:16 +0100, Ian Field wrote:

Have the limit screws been known to go out of adjustment all by
themselves?

As a firm believer of "if it aint broke don't fix it" I haven't
touched
the limit screws since I scrounged the bike on freecycle a
couple
of
years ago -
its only in the past week or so the chain started jumping over
the
biggest sprocket and attacking the spokes.

When I set about adjusting the limit screws, I got the
impression
that
they weren't even in play!

The screws don't appear to have much friction, so I'm wondering
how
long
they might stay set?

Let's assume that the limit screw was properly adjusted.

The limit screw would stop the derailleur from pushing the chain
into
the
spokes, regardless of the cable tension adjustment. Furthermore,
it's
unlikely that the limit screws would vibrate loose under normal
use.

A more likely scenario is that the bike fell on the derailleur.
The
result is that the hanger or dropout was bent slightly inward.
This
means
that the previous inward limit is now closer to the wheel. It
also
means
that all the index positions are now off slightly.

You can usually check the dropout/hanger alignment by eye. You
can
usually bend it back into a vertical position by inserting an
allen
key
into the derailleur and using it for leverage. There's also a
shop
tool
you can use to set measure and set the dropout/hanger.

On one occasion the derailleur cage actually snagged the spokes as
the
binding chain pulled it toward the wheel, once I unsnagged it I
just
pulled
it until it looked about right - by pure dumb luck it was just
about
right!

Since then I've set the limit screws - I got the impression they
weren't
screwed in enough to actually be doing anything, and there seemed
to
be
little or no friction on the screws. My question was pretty much
about
whether they're likely to have gone out of adjustment all by
themselves.

Not ever noticed it with the derailleurs I've used, any closeness to
spokes has been caused by whacking the derailleur mount in a crash,
collecting a polythene bag in the chain or wear of the parallelogram
pivots. The last was subtle and only really affected a lean of the
mechanism, not it's function or risk of fouling spokes.

I remember that Suntour had adjusting setscrews with a ridge of
plastic so making absolutely sure that the setscrews would not budge
under vibration. If yours does not have this or strong springs
under
the set-screws then use boiled linseed oil, threadlock, paint or
nail
varnish to lock them

ISTR a tube of Loctite flange sealant in the shed somewhere - it never
sets
completely but comes out the tube fairly runny and becomes tacky over
a
few
days.

AFAICR the only thread lock I have is the permanent stuff that would
destroy
things before coming undone.

If that worries you, use your pink nail varnish.

Funnily enough, I've got some of that for sealing the adjustment of
presettable components in my electronics projects.

As long as the screw is degreased first wiih IPA or acetone, it will
stick fast on metals.

So what happens next time I need to adjust it?

On Tuesday, May 28, 2013 1:01:24 PM UTC-4, Ian Field wrote:
"Stephen Bauman" wrote in message

...

On Tue, 28 May 2013 17:31:50 +0100, Ian Field wrote:



snip





I did some work on the gear cable early on, but I don't recall adjusting

the stop screws - it seemed to adjust OK just by setting the cable

right.



No!!! You want to adjust the limit screws BEFORE you put in the cable.

That's easy for the outer (high) limit. It's also easy for the inner

(low) limit by pushing on the derailleur body. An alternate is to set the

outer limit, and put in the cable. Then pull on the bare cable to move

the derailleur all the way inward.



You want the derailleur by itself to guarantee that it will always be on

the rear cluster. You don't want to depend on shifter stops.





Back then I was well aware to not mess with things I hadn't yet learned

about unless I had no choice.

It's ALWAYS a GOOD idea to Check the limit screws on any bike you get. A chain going off and between the smallest cog and frame can cause a jam and crash. A chain going off the biggest cog and onto the wheel can do a VERY NICE job of weakening the drive side spokes by cutting into them. Then you start getting broken spokes.

Cheers