Simplex Multiplicator - does it help?

still just me said:

I know SImplex used to recommend these for their bar ends. Did it make
much difference? It looks like the amount of leverage gained would be
minimal and offset by the increase in "play" introduced by having
another mechanism in what would otherwise be a single cable.

But, I've never used one. Anyone have experience with one first hand,
maybe before and after?

Had one quite a while ago, left it out later, didn't seem to make any
difference

--
/Marten

info(apestaartje)m-gineering(punt)nl

My understanding was that these things were primarily for tandems but used
on singles too when cables stretched more than they do today.

I asked a similar question a while back as I have some NOS Simplex shifters,
etc. Seem to remember that Sheldon Brown referenced them in his website
somewhere too.

Gary Jacobson
Rosendale, NY

M-gineering" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

still just me said:

I know SImplex used to recommend these for their bar ends. Did it make
much difference? It looks like the amount of leverage gained would be
minimal and offset by the increase in "play" introduced by having
another mechanism in what would otherwise be a single cable. But, I've
never used one. Anyone have experience with one first hand,
maybe before and after?

Had one quite a while ago, left it out later, didn't seem to make any
difference

--
/Marten

info(apestaartje)m-gineering(punt)nl

Gary Jacobson said:

My understanding was that these things were primarily for tandems but used
on singles too when cables stretched more than they do today.

I asked a similar question a while back as I have some NOS Simplex shifters,
etc. Seem to remember that Sheldon Brown referenced them in his website
somewhere too.

Gary Jacobson
Rosendale, NY

M-gineering" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

still just me said:

I know SImplex used to recommend these for their bar ends. Did it make
much difference? It looks like the amount of leverage gained would be
minimal and offset by the increase in "play" introduced by having
another mechanism in what would otherwise be a single cable. But, I've
never used one. Anyone have experience with one first hand,
maybe before and after?

Had one quite a while ago, left it out later, didn't seem to make any
difference

It's a demultiplicator. it's aim-so very French-was to decrease cable
pull at the derailleur, thereby increasing "feel" at the lever, or so
the ad I saw for it said. Nothing to do with streach or tandems or
anything ratiional. I had one-even made a braze-on for it-with Simplex
barends and it would pull a 7 speed freewheel just fine. I didn't
notice any increased feel but then, I'm not French. I still have one
floating around somewhere.
Phil Brown..

Quoted message said:

M-gineering" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

still just me said:

I know SImplex used to recommend these for their bar ends. Did it make
much difference? It looks like the amount of leverage gained would be
minimal and offset by the increase in "play" introduced by having
another mechanism in what would otherwise be a single cable. But, I've
never used one. Anyone have experience with one first hand,
maybe before and after?

Had one quite a while ago, left it out later, didn't seem to make any
difference

In article <[email hidden]>,

Gary Jacobson said:

My understanding was that these things were primarily for tandems but used
on singles too when cables stretched more than they do today.

I asked a similar question a while back as I have some NOS Simplex shifters,
etc. Seem to remember that Sheldon Brown referenced them in his website
somewhere too.

Do not top post. I fixed it for you.

Cables do not stretch.

--
Michael Press

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

Quoted message said:

Quoted message said:

M-gineering" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

still just me wrote:
> I know SImplex used to recommend these for their bar ends. Did it make
> much difference? It looks like the amount of leverage gained would be
> minimal and offset by the increase in "play" introduced by having
> another mechanism in what would otherwise be a single cable. But, I've
> never used one. Anyone have experience with one first hand,
> maybe before and after?

Had one quite a while ago, left it out later, didn't seem to make any
difference

In article <[email hidden]>,

Gary Jacobson said:

My understanding was that these things were primarily for tandems but
used
on singles too when cables stretched more than they do today.

I asked a similar question a while back as I have some NOS Simplex
shifters,
etc. Seem to remember that Sheldon Brown referenced them in his website
somewhere too.

Do not top post. I fixed it for you.

Cables do not stretch.

--
Michael Press

I doubt I'll ever understand the issue with top posting, but I believe you
on both counts.
Was all that hullabaloo about die drawn cables years back just marketing?
Are you saying that brake cables don't stretch either?

Gary Jacobson
Rosendale, NY

In article <[email hidden]>,

Gary Jacobson said:

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

Quoted message said:

Quoted message said:

M-gineering" <[email hidden]> wrote in message
news:[email hidden]...
> still just me wrote:
>> I know SImplex used to recommend these for their bar ends. Did it make
>> much difference? It looks like the amount of leverage gained would be
>> minimal and offset by the increase in "play" introduced by having
>> another mechanism in what would otherwise be a single cable. But, I've
>> never used one. Anyone have experience with one first hand,
>> maybe before and after?
>
> Had one quite a while ago, left it out later, didn't seem to make any
> difference

In article <[email hidden]>,

Gary Jacobson said:

My understanding was that these things were primarily for tandems but
used
on singles too when cables stretched more than they do today.

I asked a similar question a while back as I have some NOS Simplex
shifters,
etc. Seem to remember that Sheldon Brown referenced them in his website
somewhere too.

Do not top post. I fixed it for you.

Cables do not stretch.

I doubt I'll ever understand the issue with top posting, but I believe you
on both counts.

Thanks.

Quoted message said:

Was all that hullabaloo about die drawn cables years back just marketing?

Probably that and an attempt to make the surface of the cable
smooth and move more easily through the cable housing.

Quoted message said:

Are you saying that brake cables don't stretch either?

Yes.
The twisted wire cables themselves do not stretch.
Suppose a cable stretched under load. It would become
thinner, and unable to sustain as much load as
previously, then stretch more. If the cyclist were to
take up the slack at the brake's cable attachment, the
cable could stretch until it parted. This does not
happen. What you see when the brake goes out of
adjustment, seemingly from cable stretch, is in fact
scrunching up (technical term) of the cable housing
ends at various cable stop. Cable stretch is actually
contraction of the cable housing run. The ferrules can
cause contraction of the cable housing run by being the
wrong size, or not completelys seated at installation.
Some cable housing stops should _not_ have ferrules,
and installing them causes shortening of the cable
housing run as the ferrule collapses and the cable
housing sinks into the cable housing stop.

--
Michael Press

Dear Gary,

Twisted wire cables do stretch, but not much.

After you listen to all the arguments (which have been made before on
RBT), you can have fun with a cable stretch calculator:

http://www.spaceagecontrol.com/calcstre.htm

Cheers,

Carl Fogel

Gary Jacobson said:

I doubt I'll ever understand the issue with top posting, but I believe you
on both counts.
Was all that hullabaloo about die drawn cables years back just marketing?
Are you saying that brake cables don't stretch either?

Gary Jacobson
Rosendale, NY

Quoted message said:

Dear Gary,

Twisted wire cables do stretch, but not much.

After you listen to all the arguments (which have been made before on
RBT), you can have fun with a cable stretch calculator:

http://www.spaceagecontrol.com/calcstre.htm

Cheers,

Carl Fogel

Thanks for adding some independent science, Carl.

Someone said:

I know SImplex used to recommend these for their bar ends. Did it make
much difference?

Actually, yes. The old Simplex derailers were pretty pitiful by
modern standards, and when used with barcons, cable breakage was a
constant issue.

The demultiplier (démultiplicateur in French) mounted down at the
bottom of the seat tube. The section of cable from the shift lever to
the demultiplier was under less tension and traveled farther than the
rear section of cable. This improved cable life and also gave more
lever travel per shift, making it easier to fine tune the non-indexed
shifting.

Quoted message said:

It looks like the amount of leverage gained would be
minimal and offset by the increase in "play" introduced by having
another mechanism in what would otherwise be a single cable.

Nope. The "mechanism" replaced a the cable guide (or, sometimes a
short length of housing) above the bottom bracket, and the pivot of
the demultiplier actually _reduced_ the friction at this location.

By the way, the QBP "Travel Agent" for brakes is basically the same
thing, only with longer travel than the demultiplier gave.

Sheldon "Mechanical Advantage" Brown

Sheldon Brown said:

This improved cable life and also gave more
lever travel per shift, making it easier to fine tune the non-indexed
shifting.

Really? More travel per shift? Seems opposite the way you'd want to go
with old style gear and bar cons.

Carl Fogel said:

Twisted wire cables do stretch, but not much.

After you listen to all the arguments (which have been made before on
RBT), you can have fun with a cable stretch calculator:

http://www.spaceagecontrol.com/calcstre.htm

For what it's worth, that calculator is for 7x7 rope lay cable, which
in my experience is quite a bit stretchier than the much more common
(for bicycles) 1x19 cable.

49-strand cable, which pops up from time to time in bike applications,
looks good and is more supple than 19-strand cable. But its
elasticity makes it basically useless for brake setups that require
both a large cable actuating force and a long run of cable, e.g. drum
brakes.

A quick spin through the calculator shows that a 200 pound tension (a
50-lb tug on a 4:1 brake lever) upon a 78 inch long cable of 1/16 inch
diameter causes it to stretch about half an inch-- eating up most of
the lever's throw even before housing compression, brake flex, pad
squish, etc. are taken into account. That's consistent with my
experience of 49-strand cable.

One of the chief benefits of the transition to linear-pull brakes has
been the corollary reduction in brake cable tension due to longer
cable travel. Brake system mush attributable to cable stretch is
reduced by almost half compared to earlier brakes.

Chalo

Quoted message said:

Sheldon Brown said:

This improved cable life and also gave more
lever travel per shift, making it easier to fine tune the non-indexed
shifting.

still just me said:

Really? More travel per shift? Seems opposite the way you'd want to go
with old style gear and bar cons.

Works on a no-index tandem, more lever travel really helps locate shifts.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

In article
<[email hidden]
egroups.com>,

Quoted message said:

Dear Gary,

Twisted wire cables do stretch, but not much.

After you listen to all the arguments (which have been made before on
RBT), you can have fun with a cable stretch calculator:

http://www.spaceagecontrol.com/calcstre.htm

Are you talking about elastic or plastic deformation?
How much elastic deformation does a bicycle brake cable
undergo at the forces they are designed for?

Quoted message said:

Gary Jacobson said:

I doubt I'll ever understand the issue with top posting, but I believe you
on both counts.
Was all that hullabaloo about die drawn cables years back just marketing?
Are you saying that brake cables don't stretch either?

--
Michael Press

Chalo said:

One of the chief benefits of the transition to linear-pull brakes has
been the corollary reduction in brake cable tension due to longer
cable travel. Brake system mush attributable to cable stretch is
reduced by almost half compared to earlier brakes.

Ditto for cable friction. Friction force around bends also gets worse
with tension. It's one of those self-perpetuating (or self-
amplifying) problems.

I assume that's the reason that brake levers now have their own return
springs, plus the little clips that keep the cable heads in place.
Lightly pushing the cable back from the lever end means less spring
tension is required at the caliper end. Then, during brake
application, the cable's under less tension, so there's less friction
in the bends. The benefit is larger than one might think.

- Frank Krygowski

Quoted message said:

I assume that's the reason that brake levers now have their own return
springs, plus the little clips that keep the cable heads in place.
Lightly pushing the cable back from the lever end means less spring
tension is required at the caliper end. Then, during brake
application, the cable's under less tension, so there's less friction
in the bends. The benefit is larger than one might think.

That may be true, but it has little to do with cable stretch. We used
to string brakes all the time, day after day. Ferrules always fit and
housing ends were always ground flat. Hook them up tight, give a few
hard pulls on the levers, and guess what? Cable slack. It wasn't the
housing, or the fittings, or friction - it was cable stretch.

After the initial pulls, the problem seems to abate to undetectable
levels.

A Muzi said:

Quoted message said:

Sheldon Brown said:

This improved cable life and also gave more
lever travel per shift, making it easier to fine tune the non-indexed
shifting.

still just me said:

Really? More travel per shift? Seems opposite the way you'd want to go
with old style gear and bar cons.

Works on a no-index tandem, more lever travel really helps locate shifts.

So do long levers, à là Huret.

still just me said:

Quoted message said:

I assume that's the reason that brake levers now have their own return
springs, plus the little clips that keep the cable heads in place.
Lightly pushing the cable back from the lever end means less spring
tension is required at the caliper end. Then, during brake
application, the cable's under less tension, so there's less friction
in the bends. The benefit is larger than one might think.

That may be true, but it has little to do with cable stretch.

Right. And I didn't say it did. It's just a related topic, a
progression of the conversation.

Quoted message said:

We used
to string brakes all the time, day after day. Ferrules always fit and
housing ends were always ground flat. Hook them up tight, give a few
hard pulls on the levers, and guess what? Cable slack. It wasn't the
housing, or the fittings, or friction - it was cable stretch.

After the initial pulls, the problem seems to abate to undetectable
levels.

I think that's not cable stretch either... at least, not most of it.
Here's what I think is happening:

You're snaking a cable through a housing that curves in three
dimensions. And many housings are lined with relatively soft
plastic. When you did your original setup, the cable and housing were
not in their final equilibrium position.

When you gave the hard pull on the levers, you were imparting much
more tension than you'd done during the setup. The cables shifted
slightly inside the housing, finding the shortest path from lever to
brake. They may have also squashed the plastic liner a bit. And the
housings probably also shifted position on curves. And despite what
you think, I'd bet the ferrules seated a bit more under the large
force. All this adds up to extra slack that has to be adjusted out.

My bet is that if you precisely measured a new cable length, did the
install as you described (including the hard squeeze and re-adjust)
then stripped out the cable out and precisely re-measured, you'd find
the cable length to be exactly the same.

(And even if there were any change in length, it would be very slight,
and perhaps due to some similar "settling" of the individual strands,
not actual linear stretching of the metal.)

This might be a good project for Fogel Labs, should he choose to
accept it.

- Frank Krygowski

_ said:

Quoted message said:

Quoted message said:

Sheldon Brown <[email hidden]> wrote:
> This improved cable life and also gave more
> lever travel per shift, making it easier to fine tune the non-indexed
> shifting.

still just me said:

Really? More travel per shift? Seems opposite the way you'd want to go
with old style gear and bar cons.

Works on a no-index tandem, more lever travel really helps locate shifts.

So do long levers, à là Huret.

Well, I think my question is answered anyway. I can't stand the feel
of long levers and long pulls. I thought the de-multiplicator's intent
was to give me positive leverage effect, not negative. Friction
bar-ends don't need more slop!

Quoted message said:

still just me said:

Quoted message said:

I assume that's the reason that brake levers now have their own return
springs, plus the little clips that keep the cable heads in place.
Lightly pushing the cable back from the lever end means less spring
tension is required at the caliper end. Then, during brake
application, the cable's under less tension, so there's less friction
in the bends. The benefit is larger than one might think.

That may be true, but it has little to do with cable stretch.

Right. And I didn't say it did. It's just a related topic, a
progression of the conversation.

Quoted message said:

We used
to string brakes all the time, day after day. Ferrules always fit and
housing ends were always ground flat. Hook them up tight, give a few
hard pulls on the levers, and guess what? Cable slack. It wasn't the
housing, or the fittings, or friction - it was cable stretch.

After the initial pulls, the problem seems to abate to undetectable
levels.

I think that's not cable stretch either... at least, not most of it.
Here's what I think is happening:

You're snaking a cable through a housing that curves in three
dimensions. And many housings are lined with relatively soft
plastic. When you did your original setup, the cable and housing were
not in their final equilibrium position.

When you gave the hard pull on the levers, you were imparting much
more tension than you'd done during the setup. The cables shifted
slightly inside the housing, finding the shortest path from lever to
brake. They may have also squashed the plastic liner a bit. And the
housings probably also shifted position on curves. And despite what
you think, I'd bet the ferrules seated a bit more under the large
force. All this adds up to extra slack that has to be adjusted out.

My bet is that if you precisely measured a new cable length, did the
install as you described (including the hard squeeze and re-adjust)
then stripped out the cable out and precisely re-measured, you'd find
the cable length to be exactly the same.

(And even if there were any change in length, it would be very slight,
and perhaps due to some similar "settling" of the individual strands,
not actual linear stretching of the metal.)

This might be a good project for Fogel Labs, should he choose to
accept it.

A simple test is to replace the cable, but leave the housing.

--
Joe Riel