brake failure

Michael Press

In article <dabac.3a0tz0@no-mx.forums.cyclingforums.com>,
dabac <dabac.3a0tz0@no-mx.forums.cyclingforums.com> wrote:

> jobst.brandt@stanfordalumni.org Wrote:
> > Tom Kunich wrote:
> >
> > >> I also considered using the shifter cable from an old Positron RD
> > >> to see if that would reduce the slack enough to get decent
> > >> performance out of the rear brake, as according to the yachting
> > >> world a solid wire is less springy than a multi strand wire(for a
> > >> given diameter).
> >
> > No matter how closely you pack circular cross section strands,
> > they will have less cross sectional area than an equivalent diameter
> > solid wire, however, for the forces in brake cables, the stranded
> > cables do not stretch.
> >
>
> I fear that this may bog down in another quagmire of semantics,

What is semantics? Most often when `cable stretch' is
used carelessly here it refers to a permanent relative
elongation of the cable path with respect to the housing
path. So a permanent shortening of the cable housing path
is equivalent to a permanent elongation of the brake
cable. Brake cables in use do not permanently elongate
except when individual strands fracture. Brake cables do
elastically elongate and recover. How much do they elongate
elastically? How much does a cable housing path shorten
elastically? How much do brake arms bend elastically?
I expect that the elastic elongation of the cable is the
least of these.

> but
> cables do become longer. It may well be that each individual strand
> doesn't elongate, but a cable as a whole can certainly become longer -
> presumably by the voids in the cross section compressing when the cable
> is under tension. Smaller voids, smaller diameter. And as the diameter
> decreases the virtual center that the strands are wound around gets
> smaller, thus allowing the cable to become longer even if the strands
> themselves aren't stretching.
> I once tried running some nice and thick cables originally intended for
> scooters as brake cables on my bike and they gave a hopelessly mushy
> feel that just didn't go away until I replaced them with some thinner
> but more densely laid bicycle-specific cables.

--
Michael Press

Tim McNamara

In article <dabac.3a0tz0@no-mx.forums.cyclingforums.com>,
dabac <dabac.3a0tz0@no-mx.forums.cyclingforums.com> wrote:

> jobst.brandt@stanfordalumni.org Wrote:
> > Tom Kunich wrote:
> >
> > >> I also considered using the shifter cable from an old Positron
> > >> RD to see if that would reduce the slack enough to get decent
> > >> performance out of the rear brake, as according to the yachting
> > >> world a solid wire is less springy than a multi strand wire(for
> > >> a given diameter).
> >
> > No matter how closely you pack circular cross section strands, they
> > will have less cross sectional area than an equivalent diameter
> > solid wire, however, for the forces in brake cables, the stranded
> > cables do not stretch.
> >
>
> I fear that this may bog down in another quagmire of semantics, but
> cables do become longer. It may well be that each individual strand
> doesn't elongate, but a cable as a whole can certainly become longer
> - presumably by the voids in the cross section compressing when the
> cable is under tension. Smaller voids, smaller diameter. And as the
> diameter decreases the virtual center that the strands are wound
> around gets smaller, thus allowing the cable to become longer even if
> the strands themselves aren't stretching.

How much stretch did you measure in the cables? This is one of those
"one measurement is worth a thousand opinions." Where's Fogel Labs when
you need 'em?

dabac

Well, it did stretch enough for the rear brake lever to routinely bottom out against the bar if the brake was set up for decent mud clearance when I was running cantis. W/o a similar setup immediately at hand to compare with I'd have to guess - 3 mm perhaps. Lock-up was well within reach of the barrel adjuster - as long as you were willing to accept a significant drag.

I'll have a look in the parts bin tomorrow - it might just be that I didn't have the heart to throw away an uncut and barely used length of cable despite the poor results it was giving.

jobst.brandt@stanfordalumni.org

someone wrote:

>> How much stretch did you measure in the cables?

> Well, it did stretch enough for the rear brake lever to routinely
> bottom out against the bar if the brake was set up for decent mud
> clearance when I was running cantis. W/o a similar setup
> immediately at hand to compare with I'd have to guess - 3 mm
> perhaps. Lock-up was well within reach of the barrel adjuster - as
> long as you were willing to accept a significant drag.

> I'll have a look in the parts bin tomorrow - it might just be that I
> didn't have the heart to throw away an uncut and barely used length
> of cable despite the poor results it was giving.

I don't see how cable stretch can be determined from hand lever
motion. As was mentioned, caliper arms act in bending against
elastomeric brake pads, causing elasticity in brake response. Next
time try bringing brake pads into firm contact with the rim and
determine how much cable movement occurs where it leaves the housing
anchor, compared to cable motion at the hand lever. That test occurs
at the higher cable tension portion of brake application.

Jobst Brandt

carlfogel@comcast.net

On Mon, 26 May 2008 16:07:21 -0500, Tim McNamara
<timmcn@bitstream.net> wrote:

>In article <dabac.3a0tz0@no-mx.forums.cyclingforums.com>,
> dabac <dabac.3a0tz0@no-mx.forums.cyclingforums.com> wrote:
>
>> jobst.brandt@stanfordalumni.org Wrote:
>> > Tom Kunich wrote:
>> >
>> > >> I also considered using the shifter cable from an old Positron
>> > >> RD to see if that would reduce the slack enough to get decent
>> > >> performance out of the rear brake, as according to the yachting
>> > >> world a solid wire is less springy than a multi strand wire(for
>> > >> a given diameter).
>> >
>> > No matter how closely you pack circular cross section strands, they
>> > will have less cross sectional area than an equivalent diameter
>> > solid wire, however, for the forces in brake cables, the stranded
>> > cables do not stretch.
>> >
>>
>> I fear that this may bog down in another quagmire of semantics, but
>> cables do become longer. It may well be that each individual strand
>> doesn't elongate, but a cable as a whole can certainly become longer
>> - presumably by the voids in the cross section compressing when the
>> cable is under tension. Smaller voids, smaller diameter. And as the
>> diameter decreases the virtual center that the strands are wound
>> around gets smaller, thus allowing the cable to become longer even if
>> the strands themselves aren't stretching.
>
>How much stretch did you measure in the cables? This is one of those
>"one measurement is worth a thousand opinions." Where's Fogel Labs when
>you need 'em?

Dear Tim,

Fogel Labs is suffering--achoo!--a cold probably caught in the line of
duty while visiting a fantastic private highwheeler museum.

Same old cable stretch calculator from previous threads:

http://www.spaceagecontrol.com/calc...ubmit=Calculate

Bicycle brake cables aren't laid 7x7, are usually shorter and thicker
than a radio antenna, and aren't as sensitive to length changes.

My impression is that most of the cable stretch noticed by posters in
ordinary bicycle brake cables is housing compression, seating of the
end pieces, and the bending of the cable around curves inside the
housing. That is, it's more a matter of slop than the actual
stretching of the stranded 1x6x12 cable.

Here's the start of an old thread on the subject:
http://groups.google.com/group/rec....6ffb5206ddcf4d7

Cheers,

Carl Fogel

carlfogel@comcast.net

On 26 May 2008 23:17:22 GMT, jobst.brandt@stanfordalumni.org wrote:

>Carl Fogel wrote:
>
>>>>>>> I also considered using the shifter cable from an old Positron
>>>>>>> RD to see if that would reduce the slack enough to get decent
>>>>>>> performance out of the rear brake, as according to the yachting
>>>>>>> world a solid wire is less springy than a multi strand wire(for
>>>>>>> a given diameter).
>
>>>>> No matter how closely you pack circular cross section strands,
>>>>> they will have less cross sectional area than an equivalent
>>>>> diameter solid wire, however, for the forces in brake cables,
>>>>> the stranded cables do not stretch.
>
>>>> I fear that this may bog down in another quagmire of semantics,
>>>> but cables do become longer. It may well be that each individual
>>>> strand doesn't elongate, but a cable as a whole can certainly
>>>> become longer - presumably by the voids in the cross section
>>>> compressing when the cable is under tension. Smaller voids,
>>>> smaller diameter. And as the diameter decreases the virtual center
>>>> that the strands are wound around gets smaller, thus allowing the
>>>> cable to become longer even if the strands themselves aren't
>>>> stretching.
>
>>> How much stretch did you measure in the cables? This is one of
>>> those "one measurement is worth a thousand opinions." Where's
>>> Fogel Labs when you need 'em?
>
>> Dear Tim,
>
>> Fogel Labs is suffering--achoo!--a cold probably caught in the line
>> of duty while visiting a fantastic private high-wheeler museum.
>
>> Same old cable stretch calculator from previous threads:
>
> http://tinyurl.com/4js77n
>
>> Bicycle brake cables aren't laid 7x7, are usually shorter and thicker
>> than a radio antenna, and aren't as sensitive to length changes.
>
>I don't understand what this has to do with brake cable "stretch".

[snip]

Dear Jobst,

I'm sure that you don't.

Cheers,

Carl Fogel

Tim McNamara

In article <d3fm34l9aanijigkbs9a6ppkplrfiacral@4ax.com>,
carlfogel@comcast.net wrote:

> On Mon, 26 May 2008 16:07:21 -0500, Tim McNamara
> <timmcn@bitstream.net> wrote:
>
> >In article <dabac.3a0tz0@no-mx.forums.cyclingforums.com>,
> > dabac <dabac.3a0tz0@no-mx.forums.cyclingforums.com> wrote:
> >
> >> jobst.brandt@stanfordalumni.org Wrote:
> >> > Tom Kunich wrote:
> >> >
> >> > >> I also considered using the shifter cable from an old
> >> > >> Positron RD to see if that would reduce the slack enough to
> >> > >> get decent performance out of the rear brake, as according to
> >> > >> the yachting world a solid wire is less springy than a multi
> >> > >> strand wire(for a given diameter).
> >> >
> >> > No matter how closely you pack circular cross section strands,
> >> > they will have less cross sectional area than an equivalent
> >> > diameter solid wire, however, for the forces in brake cables,
> >> > the stranded cables do not stretch.
> >> >
> >>
> >> I fear that this may bog down in another quagmire of semantics,
> >> but cables do become longer. It may well be that each individual
> >> strand doesn't elongate, but a cable as a whole can certainly
> >> become longer - presumably by the voids in the cross section
> >> compressing when the cable is under tension. Smaller voids,
> >> smaller diameter. And as the diameter decreases the virtual center
> >> that the strands are wound around gets smaller, thus allowing the
> >> cable to become longer even if the strands themselves aren't
> >> stretching.
> >
> >How much stretch did you measure in the cables? This is one of
> >those "one measurement is worth a thousand opinions." Where's Fogel
> >Labs when you need 'em?
>
> Dear Tim,
>
> Fogel Labs is suffering--achoo!--a cold probably caught in the line
> of duty while visiting a fantastic private highwheeler museum.

Feel better soon, Carl!

carlfogel@comcast.net

On Mon, 26 May 2008 20:59:46 -0500, Tim McNamara
<timmcn@bitstream.net> wrote:

>In article <d3fm34l9aanijigkbs9a6ppkplrfiacral@4ax.com>,
> carlfogel@comcast.net wrote:
>
>> On Mon, 26 May 2008 16:07:21 -0500, Tim McNamara
>> <timmcn@bitstream.net> wrote:

>> >How much stretch did you measure in the cables? This is one of
>> >those "one measurement is worth a thousand opinions." Where's Fogel
>> >Labs when you need 'em?
>>
>> Dear Tim,
>>
>> Fogel Labs is suffering--achoo!--a cold probably caught in the line
>> of duty while visiting a fantastic private highwheeler museum.
>
>Feel better soon, Carl!

Dear Tim,

Thanks--on my ride today I was croaking "On your left!" so feebly that
I actually forgave some of the holiday idiots for not hearing me.

Here's an example of the kind of stuff at the museum that might appeal
to machinists like Chalo, a solid restoration hub machined as a copy
of a late-model highwheeler hub:
http://i29.tinypic.com/2eurklc.jpg

The heads of the direct spokes slip sideways into place in the hub
slots, which are all angled slightly inward for the dishing.

You can imagine how awkward it would be to bend the two-foot long
spokes into place if the holes were drilled instead of slotted.

The threaded hole on the left is one of two for attaching a decorative
dust-cover, somewhat like a modern hub-cap on a car.

Another curious detail, a modern spiral-wire solid tire:
http://i29.tinypic.com/f0xeh2.jpg

Originally, most highwheelers glued solid circular rubber tires thier
rims.

Alas, there's not much demand for solid circular rubber tires in
one-inch sizes from 48 to 66 inch outside diameter, so local bike
shops don't stock them and modern replacements are commonly used.

Many highwheelers use tires made by cutting a length of round rubber
stock to size and forcing a stout wire through a hole running the
length of the tire.

A clever clamp pulls the wire ends tight and pushes the ends of the
rubber away from where the wires meet. After the two ends are
silver-soldered together, the clamp is released to let rubber ends
move back until they touch and hide the wire joint.

But that means carrying a torch, solder, and clamp for roadside tire
repairs and some potential problems, such as the joint failing and the
tightened wire cutting into the tire.

The spiral-wire tire is the other kind used on modern highwheelers. It
has the stout corkscrew wire moulded into the rubber that you see in
the picture.

You cut a length of tire stock, leaving a few inches of wire sticking
out at either end, pull it tight around the rim, and twist each end up
like a barber pole.

Then you hook the spiral ends into each other.

When you let go, they untwist and bury themselves into the rubber
until they pull the rubber ends together.

No special vise, torch, solder, or other tools are needed, though a
gorilla might come in handy for the stretching and twisting.

Cheers,

Carl Fogel

Kerry Montgomery

<carlfogel@comcast.net> wrote in message
news:c0um34dtb988psm980snfmcl2qr7j3ej6t@4ax.com...
> On Mon, 26 May 2008 20:59:46 -0500, Tim McNamara
> <timmcn@bitstream.net> wrote:
>
>>In article <d3fm34l9aanijigkbs9a6ppkplrfiacral@4ax.com>,
>> carlfogel@comcast.net wrote:
>>
>>> On Mon, 26 May 2008 16:07:21 -0500, Tim McNamara
>>> <timmcn@bitstream.net> wrote:
>
>>> >How much stretch did you measure in the cables? This is one of
>>> >those "one measurement is worth a thousand opinions." Where's Fogel
>>> >Labs when you need 'em?
>>>
>>> Dear Tim,
>>>
>>> Fogel Labs is suffering--achoo!--a cold probably caught in the line
>>> of duty while visiting a fantastic private highwheeler museum.
>>
>>Feel better soon, Carl!
>
> Dear Tim,
>
> Thanks--on my ride today I was croaking "On your left!" so feebly that
> I actually forgave some of the holiday idiots for not hearing me.
>
> Here's an example of the kind of stuff at the museum that might appeal
> to machinists like Chalo, a solid restoration hub machined as a copy
> of a late-model highwheeler hub:
> http://i29.tinypic.com/2eurklc.jpg
>
> The heads of the direct spokes slip sideways into place in the hub
> slots, which are all angled slightly inward for the dishing.
>
> You can imagine how awkward it would be to bend the two-foot long
> spokes into place if the holes were drilled instead of slotted.
>
> The threaded hole on the left is one of two for attaching a decorative
> dust-cover, somewhat like a modern hub-cap on a car.
>
> Another curious detail, a modern spiral-wire solid tire:
> http://i29.tinypic.com/f0xeh2.jpg
>
> Originally, most highwheelers glued solid circular rubber tires thier
> rims.
>
> Alas, there's not much demand for solid circular rubber tires in
> one-inch sizes from 48 to 66 inch outside diameter, so local bike
> shops don't stock them and modern replacements are commonly used.
>
> Many highwheelers use tires made by cutting a length of round rubber
> stock to size and forcing a stout wire through a hole running the
> length of the tire.
>
> A clever clamp pulls the wire ends tight and pushes the ends of the
> rubber away from where the wires meet. After the two ends are
> silver-soldered together, the clamp is released to let rubber ends
> move back until they touch and hide the wire joint.
>
> But that means carrying a torch, solder, and clamp for roadside tire
> repairs and some potential problems, such as the joint failing and the
> tightened wire cutting into the tire.
>
> The spiral-wire tire is the other kind used on modern highwheelers. It
> has the stout corkscrew wire moulded into the rubber that you see in
> the picture.
>
> You cut a length of tire stock, leaving a few inches of wire sticking
> out at either end, pull it tight around the rim, and twist each end up
> like a barber pole.
>
> Then you hook the spiral ends into each other.
>
> When you let go, they untwist and bury themselves into the rubber
> until they pull the rubber ends together.
>
> No special vise, torch, solder, or other tools are needed, though a
> gorilla might come in handy for the stretching and twisting.
>
> Cheers,
>
> Carl Fogel

Carl,
Nice eye-candy billet hub!
The owner of the LBS I worked in many years ago would replace rubber
wheelchair tires by cutting a section of tire material to length. The tire
material was a thick-walled cylinder. He'd push a piece of wire through the
length of the tire, put that assembly on the wheelchair rim, grab one end of
the wire in a vice and the other in (vice grip?) pliers, pull really hard,
twist the wire ends together so that the twisted section stuck out radially
from the rim, bent that twisted section over to lay against the wire, and it
would slip inside the hole in the center of the tire rubber as the tire
closed up. Pretty slick, but it took a lot of strength to do it.
Kerry

carlfogel@comcast.net

On Mon, 26 May 2008 21:41:17 -0700, "Kerry Montgomery"
<kamontgo@teleport.com> wrote:

>
><carlfogel@comcast.net> wrote in message
>news:c0um34dtb988psm980snfmcl2qr7j3ej6t@4ax.com...
>> On Mon, 26 May 2008 20:59:46 -0500, Tim McNamara
>> <timmcn@bitstream.net> wrote:
>>
>>>In article <d3fm34l9aanijigkbs9a6ppkplrfiacral@4ax.com>,
>>> carlfogel@comcast.net wrote:
>>>
>>>> On Mon, 26 May 2008 16:07:21 -0500, Tim McNamara
>>>> <timmcn@bitstream.net> wrote:
>>
>>>> >How much stretch did you measure in the cables? This is one of
>>>> >those "one measurement is worth a thousand opinions." Where's Fogel
>>>> >Labs when you need 'em?
>>>>
>>>> Dear Tim,
>>>>
>>>> Fogel Labs is suffering--achoo!--a cold probably caught in the line
>>>> of duty while visiting a fantastic private highwheeler museum.
>>>
>>>Feel better soon, Carl!
>>
>> Dear Tim,
>>
>> Thanks--on my ride today I was croaking "On your left!" so feebly that
>> I actually forgave some of the holiday idiots for not hearing me.
>>
>> Here's an example of the kind of stuff at the museum that might appeal
>> to machinists like Chalo, a solid restoration hub machined as a copy
>> of a late-model highwheeler hub:
>> http://i29.tinypic.com/2eurklc.jpg
>>
>> The heads of the direct spokes slip sideways into place in the hub
>> slots, which are all angled slightly inward for the dishing.
>>
>> You can imagine how awkward it would be to bend the two-foot long
>> spokes into place if the holes were drilled instead of slotted.
>>
>> The threaded hole on the left is one of two for attaching a decorative
>> dust-cover, somewhat like a modern hub-cap on a car.
>>
>> Another curious detail, a modern spiral-wire solid tire:
>> http://i29.tinypic.com/f0xeh2.jpg
>>
>> Originally, most highwheelers glued solid circular rubber tires thier
>> rims.
>>
>> Alas, there's not much demand for solid circular rubber tires in
>> one-inch sizes from 48 to 66 inch outside diameter, so local bike
>> shops don't stock them and modern replacements are commonly used.
>>
>> Many highwheelers use tires made by cutting a length of round rubber
>> stock to size and forcing a stout wire through a hole running the
>> length of the tire.
>>
>> A clever clamp pulls the wire ends tight and pushes the ends of the
>> rubber away from where the wires meet. After the two ends are
>> silver-soldered together, the clamp is released to let rubber ends
>> move back until they touch and hide the wire joint.
>>
>> But that means carrying a torch, solder, and clamp for roadside tire
>> repairs and some potential problems, such as the joint failing and the
>> tightened wire cutting into the tire.
>>
>> The spiral-wire tire is the other kind used on modern highwheelers. It
>> has the stout corkscrew wire moulded into the rubber that you see in
>> the picture.
>>
>> You cut a length of tire stock, leaving a few inches of wire sticking
>> out at either end, pull it tight around the rim, and twist each end up
>> like a barber pole.
>>
>> Then you hook the spiral ends into each other.
>>
>> When you let go, they untwist and bury themselves into the rubber
>> until they pull the rubber ends together.
>>
>> No special vise, torch, solder, or other tools are needed, though a
>> gorilla might come in handy for the stretching and twisting.
>>
>> Cheers,
>>
>> Carl Fogel
>
>Carl,
>Nice eye-candy billet hub!
>The owner of the LBS I worked in many years ago would replace rubber
>wheelchair tires by cutting a section of tire material to length. The tire
>material was a thick-walled cylinder. He'd push a piece of wire through the
>length of the tire, put that assembly on the wheelchair rim, grab one end of
>the wire in a vice and the other in (vice grip?) pliers, pull really hard,
>twist the wire ends together so that the twisted section stuck out radially
>from the rim, bent that twisted section over to lay against the wire, and it
>would slip inside the hole in the center of the tire rubber as the tire
>closed up. Pretty slick, but it took a lot of strength to do it.
>Kerry

Dear Kerry,

Yes, that's the solid-rubber-tire-stock-with-hole method, used for
baby buggy wheels, wheelchairs, and eventually highwheelers.

What he needed to make the job easier was the special tiring vise,
which has one pair of jaws to pull the wires together for twisting,
looping, or silver-soldering, while another pair of jaws pushes the
rubber stock away from the joint to let you work on it.

Here's a page showing the special vise for straight-wire tire-stock in
action:
http://www.bikeroute.com/HiWheelers/HowMountTire.php

It makes mounting tubulars look like a stroll in the park.

The owner of the private museum prefers the spiral-wire tire stock,
which eliminates the vise and soldering (or hooking) and has other
advantages in use, but he also showed me what he considered a much
better vise for the straight-wire tire stock, one that uses a socket
wrench handle to turn a built-in ratchet that pulls the wires tight.

Cheers,

Carl Fogel

dabac

If "nothing" else changes in either set-up or riding conditions other than a switch from cable A to cable B, then what other reasons are there for not getting wheel lock prior to bottoming out with one cable when it turns out to be consistently possible with another?

An amazing amount of cable housing seating occurring during the first half mile of the 2nd ride that for some reason just didn't happen during the 3 miles of the 1st ride?

jim beam

jobst.brandt@stanfordalumni.org, although we have to wonder how he ever
graduated, wrote:
> someone wrote:
>
>>> How much stretch did you measure in the cables?
>
>> Well, it did stretch enough for the rear brake lever to routinely
>> bottom out against the bar if the brake was set up for decent mud
>> clearance when I was running cantis. W/o a similar setup
>> immediately at hand to compare with I'd have to guess - 3 mm
>> perhaps. Lock-up was well within reach of the barrel adjuster - as
>> long as you were willing to accept a significant drag.
>
>> I'll have a look in the parts bin tomorrow - it might just be that I
>> didn't have the heart to throw away an uncut and barely used length
>> of cable despite the poor results it was giving.
>
> I don't see how cable stretch can be determined from hand lever
> motion.

eh?


> As was mentioned, caliper arms act in bending against
> elastomeric brake pads, causing elasticity in brake response.

actually jobst, you know how the rear brake system is more elastic than
the front? well, that's 100% because of cable/cable run elasticity.
the pads cancel out of that equation.

> Next
> time try bringing brake pads into firm contact with the rim and
> determine how much cable movement occurs where it leaves the housing
> anchor, compared to cable motion at the hand lever. That test occurs
> at the higher cable tension portion of brake application.
>


typical ill-considered presumptive jobstian nonsense. the pads, because
of low force per area, won't deflect much. a nice long cable run otoh
most definitely will. as will calipers, levers, and even frames where
the brakes are cantilever.

again, check lever displacement per unit force comparison between front
and rear. with caliper brakes, that easily determined differential is
simply cable elasticity.

Tom Kunich

"jim beam" <spamvortex@bad.example.net> wrote in message
news:0oSdncOi6pfYLaHVnZ2dnUVZ_o_inZ2d@speakeasy.net...
> jobst.brandt@stanfordalumni.org, although we have to wonder how he ever
> graduated, wrote:
>
>> As was mentioned, caliper arms act in bending against
>> elastomeric brake pads, causing elasticity in brake response.
>
> actually jobst, you know how the rear brake system is more elastic than
> the front? well, that's 100% because of cable/cable run elasticity. the
> pads cancel out of that equation.

Jim. if you don't understand what Jobst is talking about why are you making
such stupid statements? Remove a flexible cable that stretches x. Replace it
with a stiffer cable that doesn't flex and now the pads compress. How do you
tell the difference?

> typical ill-considered presumptive jobstian nonsense. the pads, because
> of low force per area, won't deflect much. a nice long cable run otoh
> most definitely will. as will calipers, levers, and even frames where the
> brakes are cantilever.

Have you ever bothered to actually LOOK at the braking system on a bicycle?
The entire mechanism is flexible because it's being made as light as
possible.

> again, check lever displacement per unit force comparison between front
> and rear. with caliper brakes, that easily determined differential is
> simply cable elasticity.

When did you developed the ability to tell the difference between 15 ft/lbs
and 17 ft/lbs of force manually?

jim beam

Tom Kunich wrote:
> "jim beam" <spamvortex@bad.example.net> wrote in message
> news:0oSdncOi6pfYLaHVnZ2dnUVZ_o_inZ2d@speakeasy.net...
>> jobst.brandt@stanfordalumni.org, although we have to wonder how he
>> ever graduated, wrote:
>>
>>> As was mentioned, caliper arms act in bending against
>>> elastomeric brake pads, causing elasticity in brake response.
>>
>> actually jobst, you know how the rear brake system is more elastic
>> than the front? well, that's 100% because of cable/cable run
>> elasticity. the pads cancel out of that equation.
>
> Jim. if you don't understand what Jobst is talking about why are you
> making such stupid statements? Remove a flexible cable that stretches x.
> Replace it with a stiffer cable that doesn't flex and now the pads
> compress. How do you tell the difference?

where are you going to get this stiffer cable from??? if it's the same
size and made of a steel alloy, it's going to be the same stiffness.

as for the rest, if it's the same caliper, same lever, same pad, and a
shorter or longer cable, then the longer cable /will/ evidence greater
elasticity and it /cannot/ be attributable to anything else!


>
>> typical ill-considered presumptive jobstian nonsense. the pads,
>> because of low force per area, won't deflect much. a nice long cable
>> run otoh most definitely will. as will calipers, levers, and even
>> frames where the brakes are cantilever.
>
> Have you ever bothered to actually LOOK at the braking system on a
> bicycle? The entire mechanism is flexible because it's being made as
> light as possible.

indeed. that's why it's asinine to attribute it all to "elastomeric
brake pads" as jobst is doing.


>
>> again, check lever displacement per unit force comparison between
>> front and rear. with caliper brakes, that easily determined
>> differential is simply cable elasticity.
>
> When did you developed the ability to tell the difference between 15
> ft/lbs and 17 ft/lbs of force manually?

the day i got a fisherman's spring balance. you know, the type you
weigh your bike with.

btw, your unflagged snippage renders the context somewhat misconstructed.