Best Brake Cable brand?

Carl Fogel said:

Quoted message said:

Quoted message said:

>> Is there a brand or type of brake cable, especially for the rear
>> brake, that stretches the least or is just generally the best type
>> of cable?

Quoted message said:

Quoted message said:

Quoted message said:

> Elastic elongation of brake cables (stretch) is not enough to be
> felt, but if you want to minimize that which there is, buy the
> cable with the largest cross section. Stainless steel having the
> same modulus of elasticity as other steel cables, and made by the
> same process, makes no difference except being more expensive. A
> brake cable should be lubricated anyway, which prevents rust.

Quoted message said:

Quoted message said:

Quoted message said:

> Stretch, or more precisely flex, occurs in the caliper and brake
> pad. and possibly a tiny amount in the hand lever. Cable housing
> is made of a coiled steel wire that is in contact around the inside
> of a cable bend and has full contact on straight runs.

Quoted message said:

Quoted message said:

Quoted message said:

> Neither the cable nor the housing yields in use so there is no
> permanent "stretching". Some length change occurs when curves in a
> brake cable change shape under load, but even that produces
> negligible length change (cosine error).

Quoted message said:

Quoted message said:

Quoted message said:

> I think you'll find that cable motion at the brake caliper is
> essentially the same as at the hand lever. It is the caliper and
> brake pads that deform and cause "sponge".

Quoted message said:

Quoted message said:

Quoted message said:

> When installing a new cable, wipe grease on the cable with the
> fingers before inserting it in the cable housing.

Quoted message said:

Quoted message said:

Quoted message said:

For what it's worth, at least one poster can tell the difference
between the stretch in different cable lays:

======================================================================

Quoted message said:

Quoted message said:

Quoted message said:

[Carl asked:]

Quoted message said:

Quoted message said:

Quoted message said:

So if the 19-strand and the 49-strand cables are roughly the same
thickness, then the 49-strand cables must use much thinner strands,
and it's the use of many thin stands that makes them more flexible
and presumably gives them a smoother texture?

Quoted message said:

Quoted message said:

Quoted message said:

[Chalo replied:]

Quoted message said:

Quoted message said:

Quoted message said:

That's why they are more supple, but their texture is coarser (since
they are essentially seven-strand cables made of wound filaments).

Quoted message said:

Quoted message said:

Quoted message said:

[Carl asked:]

Quoted message said:

Quoted message said:

Quoted message said:

Very timidly and trying not to start any arguments, but am I wrong
in thinking that I remember emphatic statements from other posters
that cables don't stretch?

Quoted message said:

Quoted message said:

Quoted message said:

[Chalo replied:]

Quoted message said:

Quoted message said:

Quoted message said:

I've seen the assertions myself. Whether the elasticity of a
19-strand cable is significant within the relevant range of tensions
I simply don't know. However, the additional stretch in a 7x7 rope
lay cable is easy to discern. I have assumed that this is due to
relative movement of the 49-strand cable's less compacted filaments.

http://groups.google.com/group/rec.bicycles.tech/msg/20729d1569cf30be

Quoted message said:

Quoted message said:

Quoted message said:

I expect that most of the cables mentioned in this thread will be 19
strand and not the 49 strand.

======================================================================

Quoted message said:

Quoted message said:

I see no explanation in that exchange of what stretches and how much.

Quoted message said:

Quoted message said:

There is no difference in conventional and super-flex cable except
flexibility (and cost). The higher strand count arises because the
flex cable is wound of cables instead of filaments, the purpose
being to increase flexibility. These were first seen on bar end
shifters because a stiff cable would interfere with steering,
making no-hands riding more difficult. You may recall that these
shift cables also used bare chromed steel housings to reduce
housing stiffness.

Quoted message said:

Quoted message said:

Both types of cable are wound with no clearance between strands.
That means that one is no more compact than the other, the
filaments having to be close packed or the cable would act as a
coil spring, something for which a cable is not intended. Cables
are helically wound to make them constant length regardless of
bend. Every strand must pass through both the inside and outside
of a bend so that all strands bear the load without affecting cable
length.

Quoted message said:

Quoted message said:

That is why STI constant length shift cable housing uses long
helical steel strands while conventional brake cable housings uses
a coil. Shift cable is sensitive to housing length because even
small changes can interfere with derailleur position, whereas brake
force is unaffected by it. Shifting being a position function and
braking a force function.

Quoted message said:

Quoted message said:

In sight of the experiments you have pursued in other respects I
would have expected you to hang a 100lb weight on a brake cable to
show the elongation a strong brake grasp can produce. Brake hand
levers with their 4:1 mechanical advantage can be grasped with more
than 20lbs.

Quoted message said:

I shouldn't have expected you to bother to read the rest of the post
that I linked to, much less the entire thread, so here's the spoon
feeding that you seem to expect.

Quoted message said:

You see, there are calculators for cable stretch from cable companies.

Quoted message said:

Chalo took the trouble to look at the one that I mentioned. Below is
the link to the cable stretch calculator and Chalo's comments, which
are as clear and to the point as ever:

Quoted message said:

[Carl's link to cable stretch calculator:]

Quoted message said:

http://www.spaceagecontrol.com/calcstre.htm?MA%5B0%5D=50&MA%5B2%5D=60...
or http://tinyurl.com/yxc4m9

Quoted message said:

[Chalo's comment on using the calculator:]

Quoted message said:

"When I enter values that would be characteristic of a rear brake
cable on one of my bikes (1.6mm dia, 200 lbf, and 38" length, I get
stretch quantities of about a quarter inch, roughly one third of the
usable range of a conventional brake lever. This is apart from
compression in the cable housing and flex at the anchor points. It
makes sense in the context of my experience with 7x7 cables."

http://groups.google.com/group/rec.bicycles.tech/msg/20729d1569cf30be

How do you reconcile that with the statement:

# Relative to other error sources, elastic cable stretch generally
# creates am extremely small error in cable-actuated position
# transducers. For precision, low-cable-tension applications, the
# error is generally below 0.01% of the full scale range of the
# position transducer. This is because the rated cable strength of
# the cable is much greater than the load applied to the cable.

I think you are confusing constructional stretch with elastic stretch
(operating stretch). Chalo claims a cable stretch of 1/4" which
results in an inch at the hand lever (4:1 ratio) in addition to
elasticity of the caliper and pad which is the principal sponge felt
by a user. Therefore, his brakes don't work at all, because that
exceeds the stroke of the hand lever, considering that at least a
third of the stroke is used to take up pad clearance to the rim.

Something does not add up here.

Jobst Brandt

Quoted message said:

Carl Fogel said:

Quoted message said:

>>> Is there a brand or type of brake cable, especially for the rear
>>> brake, that stretches the least or is just generally the best type
>>> of cable?

Quoted message said:

Quoted message said:

>> Elastic elongation of brake cables (stretch) is not enough to be
>> felt, but if you want to minimize that which there is, buy the
>> cable with the largest cross section. Stainless steel having the
>> same modulus of elasticity as other steel cables, and made by the
>> same process, makes no difference except being more expensive. A
>> brake cable should be lubricated anyway, which prevents rust.

Quoted message said:

Quoted message said:

>> Stretch, or more precisely flex, occurs in the caliper and brake
>> pad. and possibly a tiny amount in the hand lever. Cable housing
>> is made of a coiled steel wire that is in contact around the inside
>> of a cable bend and has full contact on straight runs.

Quoted message said:

Quoted message said:

>> Neither the cable nor the housing yields in use so there is no
>> permanent "stretching". Some length change occurs when curves in a
>> brake cable change shape under load, but even that produces
>> negligible length change (cosine error).

Quoted message said:

Quoted message said:

>> I think you'll find that cable motion at the brake caliper is
>> essentially the same as at the hand lever. It is the caliper and
>> brake pads that deform and cause "sponge".

Quoted message said:

Quoted message said:

>> When installing a new cable, wipe grease on the cable with the
>> fingers before inserting it in the cable housing.

Quoted message said:

Quoted message said:

> For what it's worth, at least one poster can tell the difference
> between the stretch in different cable lays:

======================================================================

Quoted message said:

Quoted message said:

> [Carl asked:]

Quoted message said:

Quoted message said:

> So if the 19-strand and the 49-strand cables are roughly the same
> thickness, then the 49-strand cables must use much thinner strands,
> and it's the use of many thin stands that makes them more flexible
> and presumably gives them a smoother texture?

Quoted message said:

Quoted message said:

> [Chalo replied:]

Quoted message said:

Quoted message said:

> That's why they are more supple, but their texture is coarser (since
> they are essentially seven-strand cables made of wound filaments).

Quoted message said:

Quoted message said:

> [Carl asked:]

Quoted message said:

Quoted message said:

> Very timidly and trying not to start any arguments, but am I wrong
> in thinking that I remember emphatic statements from other posters
> that cables don't stretch?

Quoted message said:

Quoted message said:

> [Chalo replied:]

Quoted message said:

Quoted message said:

> I've seen the assertions myself. Whether the elasticity of a
> 19-strand cable is significant within the relevant range of tensions
> I simply don't know. However, the additional stretch in a 7x7 rope
> lay cable is easy to discern. I have assumed that this is due to
> relative movement of the 49-strand cable's less compacted filaments.

http://groups.google.com/group/rec.bicycles.tech/msg/20729d1569cf30be

Quoted message said:

Quoted message said:

> I expect that most of the cables mentioned in this thread will be 19
> strand and not the 49 strand.
======================================================================

Quoted message said:

Quoted message said:

I see no explanation in that exchange of what stretches and how much.

Quoted message said:

Quoted message said:

There is no difference in conventional and super-flex cable except
flexibility (and cost). The higher strand count arises because the
flex cable is wound of cables instead of filaments, the purpose
being to increase flexibility. These were first seen on bar end
shifters because a stiff cable would interfere with steering,
making no-hands riding more difficult. You may recall that these
shift cables also used bare chromed steel housings to reduce
housing stiffness.

Quoted message said:

Quoted message said:

Both types of cable are wound with no clearance between strands.
That means that one is no more compact than the other, the
filaments having to be close packed or the cable would act as a
coil spring, something for which a cable is not intended. Cables
are helically wound to make them constant length regardless of
bend. Every strand must pass through both the inside and outside
of a bend so that all strands bear the load without affecting cable
length.

Quoted message said:

Quoted message said:

That is why STI constant length shift cable housing uses long
helical steel strands while conventional brake cable housings uses
a coil. Shift cable is sensitive to housing length because even
small changes can interfere with derailleur position, whereas brake
force is unaffected by it. Shifting being a position function and
braking a force function.

Quoted message said:

Quoted message said:

In sight of the experiments you have pursued in other respects I
would have expected you to hang a 100lb weight on a brake cable to
show the elongation a strong brake grasp can produce. Brake hand
levers with their 4:1 mechanical advantage can be grasped with more
than 20lbs.

Quoted message said:

I shouldn't have expected you to bother to read the rest of the post
that I linked to, much less the entire thread, so here's the spoon
feeding that you seem to expect.

Quoted message said:

You see, there are calculators for cable stretch from cable companies.

Quoted message said:

Chalo took the trouble to look at the one that I mentioned. Below is
the link to the cable stretch calculator and Chalo's comments, which
are as clear and to the point as ever:

Quoted message said:

[Carl's link to cable stretch calculator:]

Quoted message said:

http://www.spaceagecontrol.com/calcstre.htm?MA%5B0%5D=50&MA%5B2%5D=60...
or http://tinyurl.com/yxc4m9

Quoted message said:

[Chalo's comment on using the calculator:]

Quoted message said:

"When I enter values that would be characteristic of a rear brake
cable on one of my bikes (1.6mm dia, 200 lbf, and 38" length, I get
stretch quantities of about a quarter inch, roughly one third of the
usable range of a conventional brake lever. This is apart from
compression in the cable housing and flex at the anchor points. It
makes sense in the context of my experience with 7x7 cables."

http://groups.google.com/group/rec.bicycles.tech/msg/20729d1569cf30be

How do you reconcile that with the statement:

# Relative to other error sources, elastic cable stretch generally
# creates am extremely small error in cable-actuated position
# transducers. For precision, low-cable-tension applications, the
# error is generally below 0.01% of the full scale range of the
# position transducer. This is because the rated cable strength of
# the cable is much greater than the load applied to the cable.

I think you are confusing constructional stretch with elastic stretch
(operating stretch). Chalo claims a cable stretch of 1/4" which
results in an inch at the hand lever (4:1 ratio) in addition to
elasticity of the caliper and pad which is the principal sponge felt
by a user. Therefore, his brakes don't work at all, because that
exceeds the stroke of the hand lever, considering that at least a
third of the stroke is used to take up pad clearance to the rim.

Something does not add up here.

Jobst Brandt

Dear Jobst,

I think that you are confusing mechanicl brake levers with electrical
transducers.

Cheers,

Carl Fogel

Quoted message said:

Quoted message said:

Quoted message said:

[Chalo's comment on using the calculator:]

Quoted message said:

"When I enter values that would be characteristic of a rear brake
cable on one of my bikes (1.6mm dia, 200 lbf, and 38" length, I get
stretch quantities of about a quarter inch, roughly one third of the
usable range of a conventional brake lever. This is apart from
compression in the cable housing and flex at the anchor points. It
makes sense in the context of my experience with 7x7 cables."

Quoted message said:

Quoted message said:

I think you are confusing constructional stretch with elastic stretch
(operating stretch). Chalo claims a cable stretch of 1/4" which
results in an inch at the hand lever (4:1 ratio) in addition to
elasticity of the caliper and pad which is the principal sponge felt
by a user. Therefore, his brakes don't work at all, because that
exceeds the stroke of the hand lever, considering that at least a
third of the stroke is used to take up pad clearance to the rim.

Something does not add up here.

Quoted message said:

Dear Jobst,

I think that you are confusing mechanicl brake levers with electrical
transducers.

My thoughts on the above:
Chalo's 200 lb tension on the cable seems to be an extremely high
value. We know Chalo's a very large, very strong guy who would require
- and be able to deliver - high brake forces. But I think the typical
rider will never apply his full grip strength to the brake, unless the
brake system is defective.

FWIW, as part of a classroom design exercise, I had one of my students
squeeze an old Shimano drop bar brake lever as hard as he could. The
lever was held open by a machine screw acting as the cable would act.
The student had no problem causing the lever to yield and bend all the
way to the bar. He was a pretty strong guy, but not outrageously so.

It wouldn't be hard to measure the amount of lever motion at the bars.
As Jobst says, it's got several sources. If someone wants to evaluate
where lost motion comes from, they could eliminate one source after
another, using a game scale (or something similar) to apply a
consistent lever force.

For example, measure lever motion on the brake in normal condition;
then measure with the rim-to-pad clearance adjusted to zero;
then with the cables carefully straightened, as I described above;
then measure with steel blocks replacing rubber brake pads;
then measure with the caliper end of the cable fixed to the caliper end
of the housing, so you're seeing only the effects of the inner cable
and housing, including response to curvature;
then compute the inner wire's tension via lever geometry, and measure
the wire's stretch under that straight-line tension;
.... and so on.

This would show what percentage of lost motion comes from different
effects. After that, the cable & housing test could be repeated with
different cables and housings, for direct comparison.

Through all this, I'd keep in mind that most brake applications are
pretty light, at least for road bikes. I've never bent my brake levers
in real life riding!

- Frank Krygowski

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

Quoted message said:

> [Chalo's comment on using the calculator:]

> "When I enter values that would be characteristic of a rear brake
> cable on one of my bikes (1.6mm dia, 200 lbf, and 38" length, I

get

Quoted message said:

Quoted message said:

Quoted message said:

> stretch quantities of about a quarter inch, roughly one third of

the

Quoted message said:

Quoted message said:

Quoted message said:

> usable range of a conventional brake lever. This is apart from
> compression in the cable housing and flex at the anchor points.

It

Quoted message said:

Quoted message said:

Quoted message said:

> makes sense in the context of my experience with 7x7 cables."

Quoted message said:

Quoted message said:

I think you are confusing constructional stretch with elastic

stretch

Quoted message said:

Quoted message said:

Quoted message said:

(operating stretch). Chalo claims a cable stretch of 1/4" which
results in an inch at the hand lever (4:1 ratio) in addition to
elasticity of the caliper and pad which is the principal sponge

felt

Quoted message said:

Quoted message said:

Quoted message said:

by a user. Therefore, his brakes don't work at all, because that
exceeds the stroke of the hand lever, considering that at least a
third of the stroke is used to take up pad clearance to the rim.

Something does not add up here.

Quoted message said:

Dear Jobst,

I think that you are confusing mechanicl brake levers with

electrical

Quoted message said:

Quoted message said:

transducers.

My thoughts on the above:
Chalo's 200 lb tension on the cable seems to be an extremely high
value. We know Chalo's a very large, very strong guy who would

require

Quoted message said:

- and be able to deliver - high brake forces. But I think the typical
rider will never apply his full grip strength to the brake, unless the
brake system is defective.

FWIW, as part of a classroom design exercise, I had one of my students
squeeze an old Shimano drop bar brake lever as hard as he could. The
lever was held open by a machine screw acting as the cable would act.
The student had no problem causing the lever to yield and bend all the
way to the bar. He was a pretty strong guy, but not outrageously so.

It wouldn't be hard to measure the amount of lever motion at the bars.
As Jobst says, it's got several sources. If someone wants to evaluate
where lost motion comes from, they could eliminate one source after
another, using a game scale (or something similar) to apply a
consistent lever force.

For example, measure lever motion on the brake in normal condition;
then measure with the rim-to-pad clearance adjusted to zero;
then with the cables carefully straightened, as I described above;
then measure with steel blocks replacing rubber brake pads;
then measure with the caliper end of the cable fixed to the caliper

end

Quoted message said:

of the housing, so you're seeing only the effects of the inner cable
and housing, including response to curvature;
then compute the inner wire's tension via lever geometry, and measure
the wire's stretch under that straight-line tension;
... and so on.

This would show what percentage of lost motion comes from different
effects. After that, the cable & housing test could be repeated with
different cables and housings, for direct comparison.

Through all this, I'd keep in mind that most brake applications are
pretty light, at least for road bikes. I've never bent my brake

levers

Quoted message said:

in real life riding!

- Frank Krygowski

I have large strong front paws... ;-)

I've always installed new brake cables so that the brake pads are
touching or almost touching the rims, then I squeeze the brake levers as
hard as I can. This serves 2 functions, the first is a safety check on
the cables. I've had cable ends come off on several occasions during my
tests and this exercise saves me from an unpleasant surprise on the
road. The other initially stretches the cables enough so that my brakes
are adjust with the right amount of play so that I don't have to
readjust the cable length.

Chas.

Quoted message said:

Quoted message said:

Quoted message said:

> [Chalo's comment on using the calculator:]

> "When I enter values that would be characteristic of a rear brake
> cable on one of my bikes (1.6mm dia, 200 lbf, and 38" length, I get
> stretch quantities of about a quarter inch, roughly one third of the
> usable range of a conventional brake lever. This is apart from
> compression in the cable housing and flex at the anchor points. It
> makes sense in the context of my experience with 7x7 cables."

Quoted message said:

Quoted message said:

I think you are confusing constructional stretch with elastic stretch
(operating stretch). Chalo claims a cable stretch of 1/4" which
results in an inch at the hand lever (4:1 ratio) in addition to
elasticity of the caliper and pad which is the principal sponge felt
by a user. Therefore, his brakes don't work at all, because that
exceeds the stroke of the hand lever, considering that at least a
third of the stroke is used to take up pad clearance to the rim.

Something does not add up here.

Quoted message said:

Dear Jobst,

I think that you are confusing mechanicl brake levers with electrical
transducers.

My thoughts on the above:
Chalo's 200 lb tension on the cable seems to be an extremely high
value. We know Chalo's a very large, very strong guy who would require
- and be able to deliver - high brake forces. But I think the typical
rider will never apply his full grip strength to the brake, unless the
brake system is defective.

[snip]

Dear Frank,

At the 4:1 ratio mentioned, a 50-lb squeeze should provide 200 lbs of
force, which is within the reach of most grown men.

Since the detail may be getting lost, Chalo's reply compared 7x7 laid
cable to 1x6x12 cable. He could feel roughly the stretch predicted by
the cable company's stretch calculator on 7x7, which is the stretchier
kind of cable.

I agree that good brakes shouldn't need the rider's full strength to
work well.

Cheers,

Carl Fogel

* * Chas said:

<[email hidden]> wrote in message

< big snip>

Quoted message said:

Quoted message said:

[email hidden]> wrote
Through all this, I'd keep in mind that most brake applications are
pretty light, at least for road bikes. I've never bent my brake

levers

Quoted message said:

in real life riding!

- Frank Krygowski

I have large strong front paws... ;-)

I've always installed new brake cables so that the brake pads are
touching or almost touching the rims, then I squeeze the brake levers as
hard as I can. This serves 2 functions, the first is a safety check on
the cables.

The more important function it serves is to seat the cable head and
housings into their stops.

Quoted message said:

I've had cable ends come off on several occasions during my
tests and this exercise saves me from an unpleasant surprise on the
road.

Please tell me what is this unpleasantness.

Quoted message said:

The other initially stretches the cables enough so that my brakes
are adjust with the right amount of play so that I don't have to
readjust the cable length.

Yes, well, "stretches" isn't what most people think. What's going on is
compression.

Quoted message said:

Chas.

Robin Hubert

"Robin Hubert" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

* * Chas said:

<[email hidden]> wrote in message

< snip>

Quoted message said:

Quoted message said:

I have large strong front paws... ;-)

I've always installed new brake cables so that the brake pads are
touching or almost touching the rims, then I squeeze the brake

levers as

Quoted message said:

Quoted message said:

hard as I can. This serves 2 functions, the first is a safety check

on

Quoted message said:

Quoted message said:

the cables.

The more important function it serves is to seat the cable head and
housings into their stops.

I file or grind cable housing ends to make sure that cable housings
firmly seat into the furrels so they don't move any further. Cable ends
may seat into upright bar levers but not MTB bars.

Quoted message said:

Quoted message said:

I've had cable ends come off on several occasions during my
tests and this exercise saves me from an unpleasant surprise on the
road.

Please tell me what is this unpleasantness.

DOH! What happens when you apply the brakes and the cable end breaks
off?

Quoted message said:

Quoted message said:

The other initially stretches the cables enough so that my brakes
are adjust with the right amount of play so that I don't have to
readjust the cable length.

Yes, well, "stretches" isn't what most people think. What's going on

is

Quoted message said:

compression.

I've installed hundreds of brake cables. A new brake cable can stretch a
1/4" or mare and it maintains the length after the lever is released.

Quoted message said:

Quoted message said:

Chas.

Robin Hubert

* * Chas said:

I've installed hundreds of brake cables. A new brake cable can stretch a
1/4" or mare and it maintains the length after the lever is released.

I installed a new rear shift cable recently. Bar end friction
shifters, cables under handlebar tape.

The shift lever was all the way in the small cog position, as was the
derailleur. I lubed the cable lightly, ran it through the old (lined)
housing, pulled out all the slack with pliers, and tightened the
derailleur's cable clamp bolt.

Then, bike still on workstand, I cranked and shifted a couple times.
The slack was back. The shifter required maybe ten degrees of motion
before it would move the derailleur.

Did the cable stretch? No way. Shift forces are too light by far.

What was happening was everything in the cable path was settling back
into position. For example, the inner wire was settling into the
shortest path around the complex curves, the cable ends were fully
seating, etc.

It's not stretch.

- Frank Krygowski

Quoted message said:

* * Chas said:

I've installed hundreds of brake cables. A new brake cable can
stretch a 1/4" or mare and it maintains the length after the lever
is released.

I installed a new rear shift cable recently. Bar end friction
shifters, cables under handlebar tape.

The shift lever was all the way in the small cog position, as was the
derailleur. I lubed the cable lightly, ran it through the old (lined)
housing, pulled out all the slack with pliers, and tightened the
derailleur's cable clamp bolt.

Then, bike still on workstand, I cranked and shifted a couple times.
The slack was back. The shifter required maybe ten degrees of motion
before it would move the derailleur.

Did the cable stretch? No way. Shift forces are too light by far.

What was happening was everything in the cable path was settling back
into position. For example, the inner wire was settling into the
shortest path around the complex curves, the cable ends were fully
seating, etc.

It's not stretch.

Or, you're just too weak to pull the cable tight enough in the first place.

HTH <eg>

Quoted message said:

* * Chas said:

I've installed hundreds of brake cables. A new brake cable can stretch a
1/4" or mare and it maintains the length after the lever is released.

I installed a new rear shift cable recently. Bar end friction
shifters, cables under handlebar tape.

The shift lever was all the way in the small cog position, as was the
derailleur. I lubed the cable lightly, ran it through the old (lined)
housing, pulled out all the slack with pliers, and tightened the
derailleur's cable clamp bolt.

Then, bike still on workstand, I cranked and shifted a couple times.
The slack was back. The shifter required maybe ten degrees of motion
before it would move the derailleur.

Did the cable stretch? No way. Shift forces are too light by far.

What was happening was everything in the cable path was settling back
into position. For example, the inner wire was settling into the
shortest path around the complex curves, the cable ends were fully
seating, etc.

It's not stretch.

- Frank Krygowski

Dear Frank,

You apply little force to shifters, but you can apply lots of force to
brake cables.

Chas was talking about brake cables.

As Chalo pointed out, there are 7x7 laid cables with 49 strands that
stretch much more than the more common 1x6x12 laid cables with 19
strands.

The cable stretch calculator that I mentioned is for stretchier 7x7:

http://www.spaceagecontrol.com/calcstre.htm?MA%5B0%5D=50&MA%5B2%5D=60...
or http://tinyurl.com/yxc4m9

Cheers,

Carl Fogel

Quoted message said:

Quoted message said:

* * Chas said:

I've installed hundreds of brake cables. A new brake cable can stretch a
1/4" or mare and it maintains the length after the lever is released.

I installed a new rear shift cable recently. Bar end friction
shifters, cables under handlebar tape.

The shift lever was all the way in the small cog position, as was the
derailleur. I lubed the cable lightly, ran it through the old (lined)
housing, pulled out all the slack with pliers, and tightened the
derailleur's cable clamp bolt.

Then, bike still on workstand, I cranked and shifted a couple times.
The slack was back. The shifter required maybe ten degrees of motion
before it would move the derailleur.

Did the cable stretch? No way. Shift forces are too light by far.

What was happening was everything in the cable path was settling back
into position. For example, the inner wire was settling into the
shortest path around the complex curves, the cable ends were fully
seating, etc.

It's not stretch.

- Frank Krygowski

Dear Frank,

You apply little force to shifters, but you can apply lots of force to
brake cables.

Chas was talking about brake cables.

I understand that.

My point is that _apparent_ stretch is present even with lightly loaded
shift cables. This is an indication that people are not typically
perceiving real stretch. They're misinterpreting other effects as
cable stretch.

- Frank Krygowski