Brake Housing Compressibility Data

Anyone have data on the overall compressibility (%/force) of a brake
cable/housing assembly? The elongation of the brake cable (wire)
is readily computed, but the housing is trickier. I can estimate
it but would prefer a measurement or a specification.

Thanks

--
Joe Riel

On Sat, 03 Sep 2011 18:23:56 -0700, Joe Riel wrote:

Anyone have data on the overall compressibility (%/force) of a brake
cable/housing assembly? The elongation of the brake cable (wire)
is readily computed, but the housing is trickier. I can estimate
it but would prefer a measurement or a specification.

Thanks

Dear Joe,

If you're just interested in sponginess, meaning the distance the
lever moves for the same force (more distance for a squashier assembly
doing the same job of braking), then the articulated-link
no-compression housing people might know the answers.

But links to the Nokon and Vertebrae no-compression housings are
remarkably free of the measured comparisons that you want, which
raises the suspicion that the results wouldn't be very significant.

In any case, the compression would vary for the same length of cable
and force, depending on the curving of the housing--a straight cable
housing would compress very little in comparison to a cable with
curves.

***

If you're looking into the amount of force transmitted, the friction
of the cable and the housing seems to be the major factor:
http://www.oandp.org/jpo/library/1995_03_096.asp
http://www2.bsn.com/cycling/articles/ride-on-cable.html

Both articles involve hanging a weight to pull on one end of a
bicycle-style cable and measuring the smaller resulting pull on the
other end, the difference being what's lost to friction between the
cable and any curve in the housing.

The prosthetic testing involves shorter runs and tighter curves, but
data curves c & g show an interesting difference for steel cables
running through curved cable housings of steel and steel lined with
Teflon:

http://www.oandp.org/jpo/library/pop...pe=image&id=f5

Cheers,

Carl Fogel

On Sep 4, 1:30*am, wrote:
On Sat, 03 Sep 2011 18:23:56 -0700, Joe Riel wrote:
Anyone have data on the overall compressibility (%/force) of a brake
cable/housing assembly? *The elongation of the brake cable (wire)
is readily computed, but the housing is trickier. *I can estimate
it but would prefer a measurement or a specification.

Thanks

Dear Joe,

If you're just interested in sponginess, meaning the distance the
lever moves for the same force (more distance for a squashier assembly
doing the same job of braking), then the articulated-link
no-compression housing people might know the answers.

But links to the Nokon and Vertebrae no-compression housings are
remarkably free of the measured comparisons that you want, which
raises the suspicion that the results wouldn't be very significant.

In any case, the compression would vary for the same length of cable
and force, depending on the curving of the housing--a straight cable
housing would compress very little in comparison to a cable with
curves.


Indeed. If you have basic quality housing, such as that by Shimano or
Jagwire--performance differences really have to do with routing and
setup. The way curves are dealt with or even how noodle bends are
tweaked can make a very palpable differences in lever feel. That said,
I've not used segmented Nokon housing--which is relatively
compressionless compared to spiral stuff. Is that better? I dunno,
housing squish does seem to add a little modulation to today's
powerful calipers--some entry level bikes even come with spring loaded
cartridges and linear pull brakes--which basically mimic really
squishy housing.

writes:

On Sat, 03 Sep 2011 18:23:56 -0700, Joe Riel wrote:

Anyone have data on the overall compressibility (%/force) of a brake
cable/housing assembly? The elongation of the brake cable (wire)
is readily computed, but the housing is trickier. I can estimate
it but would prefer a measurement or a specification.

Thanks

Dear Joe,

If you're just interested in sponginess, meaning the distance the
lever moves for the same force (more distance for a squashier assembly
doing the same job of braking), then the articulated-link
no-compression housing people might know the answers.

But links to the Nokon and Vertebrae no-compression housings are
remarkably free of the measured comparisons that you want, which
raises the suspicion that the results wouldn't be very significant.

In any case, the compression would vary for the same length of cable
and force, depending on the curving of the housing--a straight cable
housing would compress very little in comparison to a cable with
curves.

***

If you're looking into the amount of force transmitted, the friction
of the cable and the housing seems to be the major factor:
http://www.oandp.org/jpo/library/1995_03_096.asp
http://www2.bsn.com/cycling/articles/ride-on-cable.html

Both articles involve hanging a weight to pull on one end of a
bicycle-style cable and measuring the smaller resulting pull on the
other end, the difference being what's lost to friction between the
cable and any curve in the housing.

The prosthetic testing involves shorter runs and tighter curves, but
data curves c & g show an interesting difference for steel cables
running through curved cable housings of steel and steel lined with
Teflon:

http://www.oandp.org/jpo/library/pop...pe=image&id=f5

Thanks for the links. I was unaware of the Nokon and Vertebrae
housings, which are interesting. I did find a paper that includes
relevant information:
http://lsc.univ-evry.fr/~eurohaptics...papers/f28.pdf.

It appears as though the stiffness of the housing is nonlinear.

--
Joe Riel

On Sep 4, 7:02*pm, Joe Riel wrote:
writes:
On Sat, 03 Sep 2011 18:23:56 -0700, Joe Riel wrote:

Anyone have data on the overall compressibility (%/force) of a brake
cable/housing assembly? *The elongation of the brake cable (wire)
is readily computed, but the housing is trickier. *I can estimate
it but would prefer a measurement or a specification.

Thanks

Dear Joe,

If you're just interested in sponginess, meaning the distance the
lever moves for the same force (more distance for a squashier assembly
doing the same job of braking), then the articulated-link
no-compression housing people might know the answers.

But links to the Nokon and Vertebrae no-compression housings are
remarkably free of the measured comparisons that you want, which
raises the suspicion that the results wouldn't be very significant.

In any case, the compression would vary for the same length of cable
and force, depending on the curving of the housing--a straight cable
housing would compress very little in comparison to a cable with
curves.

***

If you're looking into the amount of force transmitted, the friction
of the cable and the housing seems to be the major factor:
*http://www.oandp.org/jpo/library/1995_03_096.asp
*http://www2.bsn.com/cycling/articles/ride-on-cable.html

Both articles involve hanging a weight to pull on one end of a
bicycle-style cable and measuring the smaller resulting pull on the
other end, the difference being what's lost to friction between the
cable and any curve in the housing.

The prosthetic testing involves shorter runs and tighter curves, but
data curves c & g show an interesting difference for steel cables
running through curved cable housings of steel and steel lined with
Teflon:

http://www.oandp.org/jpo/library/pop..._03_096&type=i...

Thanks for the links. *I was unaware of the Nokon and Vertebrae
housings, which are interesting. *I did find a paper that includes
relevant information:http://lsc.univ-evry.fr/~eurohaptics...papers/f28.pdf.

It appears as though the stiffness of the housing is nonlinear.

It's dependant on the casing and lining (if any) on preventing
crumpling. The best casings I've seen are linen wrapped (date from
early 70's,)used as throttle linkage in commercial vehicles. The same
source is possibly available today or perhaps from motorsport
suppliers. Nylon is likely as good as you'll get for a liner. Double
wound or braided inners are possible. I think it is likely the double
wound wires stretch less for the same cross sectional area.
Also to note are that there are different pitches to the outer's
winding and the cross-section of the outer wound wire is slightly
variable. The better funcioning housings are of a finer pitch in
winding.