Barrel Adjustments on Bicycle
Claude H. Luu
About a month ago, my derailleurs went out of adjustment. My bike is
equiped with Shimano STI shifters which has a two barrel adjustments at the
downtube and one barrel adjustment at the rear derailleur.
Question: When the rear derailleur gets out of adjustment, which barrel do
I adjust? The ones at the downtube, the one at the rear derailleur? Both?
In which order should I start?
Thanks,
Claude
clau...@jps.net
Garry Lee
Steve Freides
stretch. This is especially true on new equipment, I've found, which
tends to stretch out a bit during the initial use period.
You're probably best to try turning the adjuster counterclockwise which
should back it out, which should effectively tighten up whatever may
have stretched loose a bit.
Generally, I think most folks would use the adjustment at the rear
derailleur while working on the bike in the repair stand, and save the
one on the downtube for any mid-ride corrections that might be needed.
This is what I've always done and it's worked well for me.
-S-
--
+-------------------------------------------------------------------+
+ +
+ For those of you who don't see newsgroup and mail headers, I am +
+ +
+ Steve Freides +
+ +
+-------------------------------------------------------------------+
sy...@my-dejanews.com
> Most often, when the shifting goes out of adjustment, it's due to cable
> stretch. This is especially true on new equipment, I've found, which
> tends to stretch out a bit during the initial use period.
When gear cables stretch, what is the likely cause of it? I have a habit of
putting my gear to the first (the chain on the biggest freewheel cog), which
means the cable have the most tension. Does this cause cables to stretch?
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LYDDANS
repair stand and leave the downtube adjusters for fine tuning that might be
necessary while riding. They do the same thing but to avoid confusion and to
keep track of what you're doing, I would use the derailleur adjuster first and
foremost. Good luck. Jeff.
Jobst Brandt
>> Most often, when the shifting goes out of adjustment, it's due to
>> cable stretch. This is especially true on new equipment, I've
>> found, which tends to stretch out a bit during the initial use
>> period.
> When gear cables stretch, what is the likely cause of it? I have a
> habit of putting my gear to the first (the chain on the biggest
> freewheel cog), which means the cable have the most tension. Does
> this cause cables to stretch?
Cables don't stretch any more than steel bike frames get soft. You
must have a loose anchor clamp or loose cable housing ends that seat.
Cables are steel and have no way of lengthening plastically in use.
You don't put that much force on them to even slightly approach yield
stress.
Jobst Brandt <jbr...@hpl.hp.com>
jmi...@ods.com
Jobst,
Since the cable is made up of individual strands wrapped around
each other, aren't the strands straightening out to cause the
cable stretch? Sort of like if you pulled on both ends of a
coil spring? Every bike I've ever owned and everyone I ride with
has experienced what we called 'cable stretch'. Are you saying
the cable is slipping in the anchor clamp on the derailleur on
all those bikes? I'd think that if the cable was slipping at the
rate that the 'stretch' occurs with new cables that in not too
long of a time the anchor would loosen enough to cause a catastrophic
failure. Also, why does the 'stretching' seem to go away after
a few weeks/months of riding and a few derailleur barrel adjustments?
The cable housing explanation doesn't seem to explain the case of
'stretch' when you install a new cable with the existing housing.
Jim Miller
Jobst Brandt
>>>> Most often, when the shifting goes out of adjustment, it's due to
>>>> cable stretch. This is especially true on new equipment, I've
>>>> found, which tends to stretch out a bit during the initial use
>>>> period.
>>> When gear cables stretch, what is the likely cause of it? I have a
>>> habit of putting my gear to the first (the chain on the biggest
>>> freewheel cog), which means the cable have the most tension. Does
>>> this cause cables to stretch?
>> Cables don't stretch any more than steel bike frames get soft. You
>> must have a loose anchor clamp or loose cable housing ends that seat.
>> Cables are steel and have no way of lengthening plastically in use.
>> You don't put that much force on them to even slightly approach yield
>> stress.
> Since the cable is made up of individual strands wrapped around
> each other, aren't the strands straightening out to cause the
> cable stretch? Sort of like if you pulled on both ends of a
> coil spring?
Cables are not free strands and are wrapped in layers of opposing
helixes. The strands are tightly packed around the central core that
is made of steel wires just like the rest. I think you'll see that
hanging a 100 lb weight on a gear shift cable causes an insignificant
length change that is due mainly to tightness of the layers. If they
were not counter helixes, the cable would tend to unwind and twist
under load. For resilience, some cables are wound around a rope core,
however, control cables are not.
> Every bike I've ever owned and everyone I ride with has experienced
> what we called 'cable stretch'. Are you saying the cable is slipping
> in the anchor clamp on the derailleur on all those bikes?
I'm saying that it is not "cable stretch".
> I'd think that if the cable was slipping at the rate that the
> 'stretch' occurs with new cables that in not too long of a time the
> anchor would loosen enough to cause a catastrophic failure.
Instead of saying what it's not, you might try to explain it rather
than shoving it in the corner and calling it "cable stretch". I have
not had this problem in the many years of bicycling although I listed
what Iit might be that you observe.
> Also, why does the 'stretching' seem to go away after a few
> weeks/months of riding and a few derailleur barrel adjustments? The
> cable housing explanation doesn't seem to explain the case of
> 'stretch' when you install a new cable with the existing housing.
I could just as easily ask you why the phenomenon does not appear on
my bicycle or the bicycles I maintain. Besides, if it truly were
stretch, then why would it cesae streching after a period of use?
On the other hand, if you wear off 0.2mm on the inside radius of a
cable bend, and most cables make about 360 degrees from lever to
derailleur, then it is conceivable that you would have 0.6mm to take
up on the adjusting barrell. How about inspecting the indside radius
of one of your control cables. The wear rate decreases as contact
area increases with wear.
Jobst Brandt <jbr...@hpl.hp.com>
Clownie
heard that the housing compresses when new, making the cable function as if
longer...
Brian
BQinMD
>Also, why does the 'stretching' seem to go away after
>a few weeks/months of riding and a few derailleur barrel adjustments?
>The cable housing explanation doesn't seem to explain the case of
>'stretch' when you install a new cable with the existing housing.
I "pre-stretch" my shift cables by grabbing them with a pair of pliers and
putting _lots_ of tension on them. You can feel the give as the housings
settle into the ferrules and the ferrules seat themselves in the shifters and
cable stops, snug and square. I then install the cable in the derailleur, trim
to length, and cap. I rarely have to make adjustments after the initial
installation. But of course, I didn't really stretch the cable, I just
encouraged all the other bits and pieces to find their permanent home a little
earlier than they would have if I had done a more slap-dash installation.
Bill Yoder Harford County, MD USA
jmi...@ods.com
Thanks for the explanation of what is happening when people
say the cable is 'stretching'. Before posting I had searched
Deja News to see what had been written about this subject, but
I didn't see any cases where the 'stretch' misconception had
been corrected. Your information will help me to better diagnose
shifting problems in the future.
Jobst Brandt
I have heard the moon is made of green cheese, however, let's have
something more substantial than rumor to further the cable topic.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
>> Also, why does the 'stretching' seem to go away after a few
>> weeks/months of riding and a few derailleur barrel adjustments?
>> The cable housing explanation doesn't seem to explain the case of
>> 'stretch' when you install a new cable with the existing housing.
> I "pre-stretch" my shift cables by grabbing them with a pair of
> pliers and putting _lots_ of tension on them. You can feel the give
> as the housings settle into the ferrules and the ferrules seat
> themselves in the shifters and cable stops, snug and square.
I don't visualize how you do this, cable housing and all. How do you
grasp the cable with pliers without damaging it? And how do you
anchor it so as to preload cable and housing? This seems bizarre when
this can easily be accomplished by installing the cable and pull the
shift lever to the limit stop of your derailleur to do this.
> I then install the cable in the derailleur, trim to length, and cap.
> I rarely have to make adjustments after the initial installation.
> But of course, I didn't really stretch the cable, I just encouraged
> all the other bits and pieces to find their permanent home a little
> earlier than they would have if I had done a more slap-dash
> installation.
In other words, there is no stretch. So what are you proposing with
your explanation of so-called stretch that is different than what I
stated?
Jobst Brandt <jbr...@hpl.hp.com>
Joshua_Putnam
>Bill Yoder writes:
>
>>> Also, why does the 'stretching' seem to go away after a few
>>> weeks/months of riding and a few derailleur barrel adjustments?
>>> The cable housing explanation doesn't seem to explain the case of
>>> 'stretch' when you install a new cable with the existing housing.
>> I "pre-stretch" my shift cables by grabbing them with a pair of
>> pliers and putting _lots_ of tension on them. You can feel the give
>> as the housings settle into the ferrules and the ferrules seat
>> themselves in the shifters and cable stops, snug and square.
>I don't visualize how you do this, cable housing and all. How do you
>grasp the cable with pliers without damaging it? And how do you
>anchor it so as to preload cable and housing? This seems bizarre when
>this can easily be accomplished by installing the cable and pull the
>shift lever to the limit stop of your derailleur to do this.
Or, if you're in a well-equipped bike shop. use the cable
tensioning tool, e.g. VAR 233, Park BT-2, etc., also known as a
"fourth hand." They're handy to have on systems with limited
barrel adjuster range.
The cable doesn't stretch, and the housing doesn't compress
unless the ferrules are defective, but it does seat the ferrules
on the casing and in their frame stops, pulls the lead blob on
the end of the cable into the shift lever tightly, and can
straighten out minor kinks in the cable.
If people want to call it stretch I don't mind, as long as they
realize the cable itself isn't really stretching. It's sloppy
but convenient shorthand.
--
Jo...@WolfeNet.com is Joshua Putnam / P.O. Box 13220 / Burton, WA 98013
http://www.wolfenet.com/~josh/
Andy Dingley
>When gear cables stretch, what is the likely cause of it?
Much of it comes from a crimped, twisted or deformed cable in the area
of the derailleur cable clamp. With usage, this crimp is pulled
straight again. If you're careful installing the cable (i.e. don't
mangle the ends) then you'll have so little stretch that you barely
notice it.
If "cable stretch" starts to increase over time, check that the clamp
isn't slipping (or even if the derailleur is twisting on the frame)
MikeYankee
derailleur to shift to the big ring. An hour or so later, I had to do it
again.
Hmmm, I thought. The f***ing cable is about to go.
I made it home OK on the small ring. The cable was almost broken (only 2-3
instact strands) right where you said.
BQinMD
writes:
>Bill Yoder writes:
>
[snipped stuff I didn't write]
>> I "pre-stretch" my shift cables by grabbing them with a pair of
>> pliers and putting _lots_ of tension on them. You can feel the give
>> as the housings settle into the ferrules and the ferrules seat
>> themselves in the shifters and cable stops, snug and square.
>
>I don't visualize how you do this, cable housing and all. How do you
>grasp the cable with pliers without damaging it? And how do you
>anchor it so as to preload cable and housing? This seems bizarre when
>this can easily be accomplished by installing the cable and pull the
>shift lever to the limit stop of your derailleur to do this.
I simply grasp the installed cable free end beyond where I intend to cut it. I
don't have to worry about damaging it, because it won't be on the bike when I'm
done. Of course this only works for new cables. The pulling pliers replace
the derailleur return spring, and seem to provide a little more force,
encouraging all the parts of the system to settle into their "permanent"
positions before clamping in the derailleur and trimming. The housing is held
by the last cable stop (or the barrel adjuster in the case of the rear
derailleur) and pulling on the cable puts all housing sections between the back
of the bike and the levers in compression. I've done the clamp, shift, and
adjust routine, but find if I use the pliers first I can usually replace a
broken shift cable (assuming the limit screws were properly adjusted) without
having to re-adjust the barrel adjusters.
>
>> I then install the cable in the derailleur, trim to length, and cap.
>> I rarely have to make adjustments after the initial installation.
>> But of course, I didn't really stretch the cable, I just encouraged
>> all the other bits and pieces to find their permanent home a little
>> earlier than they would have if I had done a more slap-dash
>> installation.
>
>In other words, there is no stretch. So what are you proposing with
>your explanation of so-called stretch that is different than what I
>stated?
I should have turned the sarcasm switch on when I said "pre-stretch" (although
placing it in quotes was intended to convey the fact that I know it's not
really stretch but so-called stretch). My explanation is no different than
yours, I was simply stating how I avoid having to make unnecessary adjustments
when installing or replacing cables and housings. The 4th hand tools and such
are dandy, but a little bulky for the road.
>
>Jobst Brandt <jbr...@hpl.hp.com>
David Pottage
<URL:mailto:jbr...@hpl.hp.com> wrote:
> Syloy (who?) writes:
>
>>> Most often, when the shifting goes out of adjustment, it's due to cable
>>> stretch. This is especially true on new equipment, I've found, which
>>> tends to stretch out a bit during the initial use period.
>
>> When gear cables stretch, what is the likely cause of it? I have a habit
>> of putting my gear to the first (the chain on the biggest freewheel cog),
>> which means the cable have the most tension. Does this cause cables to
>> stretch?
>
> Cables don't stretch any more than steel bike frames get soft. You
> must have a loose anchor clamp or loose cable housing ends that seat.
> Cables are steel and have no way of lengthening plastically in use.
> You don't put that much force on them to even slightly approach yield
> stress.
>
I would not normally argue with Jobst himself, because I have seen what
happens to those who do (1), but...
I distinctly remember reading in the installation institutions for a low end
shimano rear-mec, that the cable should be pre-stretched before the indexing
is adjusted, and that if the indexing goes out of adjustment, the likely
reason is that the cable has stretched some more.
As I generally believe that shimano is one of the few cycling related
companies, that actually designs from a basis of sound engineering, I am
inclined to believe them.
Is is possible perhaps, that the strands of the wire rope become closer
together by becoming hexagonal in cross section rather than circular, This
would reduce the circumference of the cable, and lengthen it slightly.
Alternatively, perhaps the ferules on the cable ends get pushed on more
snugly, increasing the slack in the run.
I await your counter arguments with interest.
(1) They get blinded with science, often in the form of long, reasoned
arguments, that look very sensible, but contain enough technical stuff, that
only a professional Mec-Eng. could follow well enough to spot any holes in
the logic.
--
David
David Pottage.
Jobst Brandt
>>> I "pre-stretch" my shift cables by grabbing them with a pair of
>>> pliers and putting _lots_ of tension on them. You can feel the
>>> give as the housings settle into the ferrules and the ferrules
>>> seat themselves in the shifters and cable stops, snug and square.
>> I don't visualize how you do this, cable housing and all. How do
>> you grasp the cable with pliers without damaging it? And how do
>> you anchor it so as to preload cable and housing? This seems
>> bizarre when this can easily be accomplished by installing the
>> cable and pull the shift lever to the limit stop of your derailleur
>> to do this.
> I simply grasp the installed cable free end beyond where I intend to
> cut it. I don't have to worry about damaging it, because it won't
> be on the bike when I'm done. Of course this only works for new
> cables.
I don't know why you call taking out the slack, "pre-stretching".
This is the reasonable way of installing cables but it does not alter
the length of the cable. In the absence of pliers for this task, you
could just attach the rear derailleur cable with the derailleur at
some lower gear position and then manually pull it toward the outer
position, loosening the anchor screw just enough to let the cable
slide. This gets the slack out and places the derailleur as close to
the correct adjustment as is practical. It also seats the housing in
the end caps and stops.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
> I distinctly remember reading in the installation institutions for a
> low end Shimano rear-mec, that the cable should be pre-stretched
> before the indexing is adjusted, and that if the indexing goes out
> of adjustment, the likely reason is that the cable has stretched
> some more.
That you read such a thing does not mean the cable stretches but
rather that it is subjected to installation slack that the user often
overlooks, like the end caps not being seated on the housing, the
cable having a kink that can straighten, or some protrusion in a cable
curve that can either be compressed or worn away in use.
Cable makers have the ability and desire to preload cable when it
comes out of the winding spinner. Cables have counter directional
helix winds that are designed to be neutral and inelastic so that the
cable with a weight hung from it does not tend to unwind or lengthen.
Any lengthening that occurs below the failure load is elastic and
recoverable, so there would be no change in adjustment. Cable making
machinery is well developed and is not something you assemble from
trial and error.
> As I generally believe that Shimano is one of the few cycling
> related companies, that actually designs from a basis of sound
> engineering, I am inclined to believe them.
Shimano most likely does not make cables but rather makes drawings and
writes specification for cable vendors, the way most companies do.
> Is is possible perhaps, that the strands of the wire rope become
> closer together by becoming hexagonal in cross section rather than
> circular, This would reduce the circumference of the cable, and
> lengthen it slightly.
That is both improbable and impossible, the mode of failure of a cable
being tensile overload for individual strands. Because the strands
are wrapped in a helix, each wire passes through the inside and
outside of a cable bend and therefore, all strands are uniformly
loaded. Of course you can kink the cable to make this not the case
but we are not talking about misuse of control cables.
> Alternatively, perhaps the ferrules on the cable ends get pushed on
> more snugly, increasing the slack in the run.
You can't have it both ways. First you give a litany of maybe's and
then go to a fall back position that has already been investigated and
proposed as the most likely cause of the observed loss of adjustment.
> I await your counter arguments with interest.
I can tell. You put a lot of conjecture together that needs sweeping
away.
Jobst Brandt <jbr...@hpl.hp.com>
philip ganderton
> > Is is possible perhaps, that the strands of the wire rope become
> > closer together by becoming hexagonal in cross section rather than
> > circular, This would reduce the circumference of the cable, and
> > lengthen it slightly.
>
> That is both improbable and impossible, the mode of failure of a cable
> being tensile overload for individual strands. Because the strands
> are wrapped in a helix, each wire passes through the inside and
> outside of a cable bend and therefore, all strands are uniformly
> loaded. Of course you can kink the cable to make this not the case
> but we are not talking about misuse of control cables.
Jobst:
With all due respect, to use your own words, "you can't have it both
ways." Either it's improbable, or it's impossible, not both. As a
statistician, I challenge you to provide any reasonable interpretation or
argument that allows an event to be *both* improbable and impossible,
unless you are focussing exclusively on the (trivial) interpretation of
improbable to include probability zero. But *if* that's what you intend,
then the term improbable is redundant.
Cheers,
philip ganderton
cr...@my-dejanews.com
> Cables have counter directional
> helix winds that are designed to be neutral and inelastic so that the
> cable with a weight hung from it does not tend to unwind or lengthen.
Some cables have a core and two opposed helical layers; others
(e.g., some SunTour cables) are "7x7", that is a core and one
helical layer, but each wire was in turn composed of a core
strand and other strands wrapped around it. Jobst, do you
know if the two designs are equally immune to stretch?
P.S. "helix wind" reminds me of "crank arm", "group set",
and "The La Brea Tar Pits".
Tom Ace
cr...@my-dejanews.com
Johan Bornman
>David Pottage writes:
>
>> I distinctly remember reading in the installation institutions for a
>> low end Shimano rear-mec, that the cable should be pre-stretched
>> before the indexing is adjusted, and that if the indexing goes out
>> of adjustment, the likely reason is that the cable has stretched
>> some more.
>
>That you read such a thing does not mean the cable stretches but
>rather that it is subjected to installation slack that the user often
>overlooks, like the end caps not being seated on the housing, the
>cable having a kink that can straighten, or some protrusion in a cable
>curve that can either be compressed or worn away in use.
>
>Cable makers have the ability and desire to preload cable when it
>comes out of the winding spinner. Cables have counter directional
>helix winds that are designed to be neutral and inelastic so that the
>cable with a weight hung from it does not tend to unwind or lengthen.
>Any lengthening that occurs below the failure load is elastic and
>recoverable, so there would be no change in adjustment. Cable making
>machinery is well developed and is not something you assemble from
>trial and error.
>
>> As I generally believe that Shimano is one of the few cycling
>> related companies, that actually designs from a basis of sound
>> engineering, I am inclined to believe them.
>
>Shimano most likely does not make cables but rather makes drawings and
>writes specification for cable vendors, the way most companies do.
>
>> Is is possible perhaps, that the strands of the wire rope become
>> closer together by becoming hexagonal in cross section rather than
>> circular, This would reduce the circumference of the cable, and
>> lengthen it slightly.
>
>That is both improbable and impossible, the mode of failure of a cable
>being tensile overload for individual strands. Because the strands
>are wrapped in a helix, each wire passes through the inside and
>outside of a cable bend and therefore, all strands are uniformly
>loaded. Of course you can kink the cable to make this not the case
>but we are not talking about misuse of control cables.
>
>> Alternatively, perhaps the ferrules on the cable ends get pushed on
>> more snugly, increasing the slack in the run.
>
>You can't have it both ways. First you give a litany of maybe's and
>then go to a fall back position that has already been investigated and
>proposed as the most likely cause of the observed loss of adjustment.
>
>> I await your counter arguments with interest.
>
>I can tell. You put a lot of conjecture together that needs sweeping
>away.
>
>Jobst Brandt <jbr...@hpl.hp.com>
Jobst, why do you have to be such an ass in so many of the discussions on this
newsgroup? The reason people discuss things here is to mostly to learn; and when
someone teaches someone else, the teacher is supposed to be patient, humble and
non-condescending - that's an unwritten rule, in my society anyway.
Your style is belligerent and cantankerous and you know it. Why should posters
pre-apologise before they question (i.e as in ask more detail) one of your
replies? To me that spells treading on eggs.
Surely when the previous poster said "alternatively" he's not trying to have it
both ways as you shot back? But that's just one point in case and, for once
please don't harp on it or ask what I mean by that.
We all raise our eyebrows and nudge-nudge, wink-wink at people who take their
cars to the garage to fix the bounciness and then lecture the mechanic to not
call that round tubie thing a shock absorber because it doesn't really absorb
any shock.
C'mon, lighten up. Who cares if we call it pre-stretching? It aptly describes
what to do to eliminate the phenomena.
This newsgroups isn't for experts only. Just like a cycling club has to work at
not alienating its novices by racing them into the ground, individuals in this
group needn't declare war on myths, lore and legend. One has to bring novices
into the fold without scaring them off and right now you're one helluva ugly
Lucifer character with a big, big spanner.
Johan Bornman
Jobst Brandt
>>> Is is possible perhaps, that the strands of the wire rope become
>>> closer together by becoming hexagonal in cross section rather than
>>> circular, This would reduce the circumference of the cable, and
>>> lengthen it slightly.
>> That is both improbable and impossible, the mode of failure of a
>> cable being tensile overload for individual strands. Because the
>> strands are wrapped in a helix, each wire passes through the inside
>> and outside of a cable bend and therefore, all strands are
>> uniformly loaded. Of course you can kink the cable to make this
>> not the case but we are not talking about misuse of control cables.
> With all due respect,
What's this got to do with respect, or are you used to lathering
people up with whom you talk?
> to use your own words, "you can't have it both ways." Either it's
> improbable, or it's impossible, not both.
If it is impossible it is by definition improbable. However, you
might like the phrasing "not only improbable, but impossible" better.
I suppose you are going to grammatically prove the contrary with
respect to control cables.
> As a statistician, I challenge you to provide any reasonable
> interpretation or argument that allows an event to be *both*
> improbable and impossible, unless you are focussing exclusively on
> the (trivial) interpretation of improbable to include probability
> zero. But *if* that's what you intend, then the term improbable is
> redundant.
I'm glad you had this opportunity to show that your statistics avoid
singularities. So now what does the control cable do?
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
>> Cables have counter directional helix winds that are designed to be
>> neutral and inelastic so that the cable with a weight hung from it
>> does not tend to unwind or lengthen.
> Some cables have a core and two opposed helical layers; others
> (e.g., some SunTour cables) are "7x7", that is a core and one
> helical layer, but each wire was in turn composed of a core strand
> and other strands wrapped around it. Jobst, do you know if the two
> designs are equally immune to stretch?
Each sub-cable is in itself a helically wound cable and therefore
follows the same rule. It may not be apparent, but the strands have a
twist in themselves that make them prefer to wrap tightly. It is for
these feature that cables don't splay in starburst at their unsecured
ends.
> P.S. "helix wind" reminds me of "crank arm", "group set",
> and "The La Brea Tar Pits".
Cable housings are also helically wound but their helix is so tight
that one usually calls them coiled. STI housing on the other hand has
a slight helix, just enough to prevent length change that otherwise
occurs with coiled cable housing. I think the terms are valid unless
the concepts mean nothing to the reader anyway.
Jobst Brandt <jbr...@hpl.hp.com>
BQinMD
writes:
>I don't know why you call taking out the slack, "pre-stretching".
>This is the reasonable way of installing cables but it does not alter
>the length of the cable. In the absence of pliers for this task, you
>could just attach the rear derailleur cable with the derailleur at
>some lower gear position and then manually pull it toward the outer
>position, loosening the anchor screw just enough to let the cable
>slide. This gets the slack out and places the derailleur as close to
>the correct adjustment as is practical. It also seats the housing in
>the end caps and stops.
>
I don't call taking out the slack "pre-stretching". Others might. It is a
figure of speech (incorrectly) used by some to explain why their new bike's
shifting drops out of adjustment as all the parts in the cable run settle in to
their permanent homes! It was in quotes as such. Later in the post, I
explained why the term "pre-stretch" was a misnomer and stated clearly (no
quotes) that I didn't really stretch the cable (because, of course, cable does
not stretch). You are absolutely right. If I chose not to use pliers, I could
simply attach the cable to the derailleur and give a tug. There are more ways
than one to skin a cat (please refrain from designating your preferred blade
type, Rockwell C numbers or other pertinent data here). You have taught me a
lot over the years, and I am grateful for your expertise and your willingness
to share it. I never thought you would teach me that agreeing with you 100%
could be so frustrating.
Jobst Brandt
> I don't call taking out the slack "pre-stretching".
As is usually the case, the subject got shifted as the concept of
stretching cables became less tenable and more apparently a case of
mis-attribution of shift problems. The claim was that cables stretch
with time and most contributors cited anecdotes to prove that control
cables stretch, usually with non-sequiturs. Then we got to slop in
the system that can be taken out... but wait. The claim was that this
occurs over a long period and is due to creep of the steel in the
cable.
Your contribution began with something to the effect that you have
also noticed this but before the end, you had reduced it to
installation slack. I don't doubt this and that one can minimize it
if the problem is understood. This is a similar issue to chain
stretch. At least half the people who use the term, truly mean that
the steel has elongated with time and force. This is NOT the case.
Calling it stretch only serves to mislead newcomers who take the words
on face value, as they should.
Jobst Brandt <jbr...@hpl.hp.com>