Cable Pull Shifter Movement Chart

Paul Kopit said:

Somewhere the chart exists but I can't seem to locate it. I'm looking
for a table that has the amount of cable that a shift lever pulls and
the amount that a rear derailleur moves for each unit of cable pull.

i.e., I'd like to know how much cable a 10 sp Campy shifter pulls and
how much movement a Shimano rear derailleur will move for that amount
of cable pull. (I read 4.6 mm) I'd like to know for multiple
combinations.

I know I've seen the info but cannot place where.

http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3946

~PB

Pete Biggs said:

Quoted message said:

I know I've seen the info but cannot place where.

http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3946

~PB

What took you so long. I must have waited 10 min. Thank you very
much!

nice chart. I notice that some numbers differ
from Sheldon Brown's per http://www.sheldonbrown.com/k7.html
ex.
Camp 10 4.15 vs 4.12
Shim 9 4.35 vs 4.34
I wonder who is right.

Since shim 9:camp 9 about 5 percent difference isn't
enough to be off by a cog if you align the center, this
smaller difference will likely enflame few, but its curious.
Ed

On 9 Mar 2005 06:01:43 -0800, "Ed Cory" <[email hidden]>

Quoted message said:

nice chart. I notice that some numbers differ
from Sheldon Brown's per http://www.sheldonbrown.com/k7.html
ex.
Camp 10 4.15 vs 4.12
Shim 9 4.35 vs 4.34
I wonder who is right.

Since shim 9:camp 9 about 5 percent difference isn't
enough to be off by a cog if you align the center, this
smaller difference will likely enflame few, but its curious.
Ed

And Campy 9 with pre 2000 derailleur 4.36.

On 9 Mar 2005 06:01:43 -0800, "Ed Cory" <[email hidden]> may

have said:

nice chart. I notice that some numbers differ
from Sheldon Brown's per http://www.sheldonbrown.com/k7.html
ex.
Camp 10 4.15 vs 4.12
Shim 9 4.35 vs 4.34
I wonder who is right.

At those levels of precision, probably both for some sample.

Quoted message said:

Since shim 9:camp 9 about 5 percent difference isn't
enough to be off by a cog if you align the center, this
smaller difference will likely enflame few, but its curious.

Probably of no consequence. One might have been from a manufacturer's
published specs and the other from measurement of the results from a
tested sample, or both might have been measured results and still give
variant figures. In theory, all of the assemblies of a given type
will perform identically. In practice, they seldom do.

--
My email address is antispammed; pull WEEDS if replying via e-mail.
Typoes are not a bug, they're a feature.
Words processed in a facility that contains nuts.

Ed Cory said:

nice chart. I notice that some numbers differ
from Sheldon Brown's per http://www.sheldonbrown.com/k7.html
ex.
Camp 10 4.15 vs 4.12
Shim 9 4.35 vs 4.34
I wonder who is right.

Just guessing, but this 0.01 mm could be manufacturing tolerance; one
got data from the designers, the other measured. Although I'm not sure
I'd believe any measurements down below about 0.10 mm.

Pat

Getting back to cable pull: Apparently, the sprocket spacing (or
sprocket pitch) is uniform across the cassette. Seems to me, then,
that the cable pull can't be exactly uniform across all the shifter's
clicks. IOW, the "shift ratio" in
http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3946 can't be a
constant.

I say this because the cable acts as a diagonal to the derailleur's
parallelogram. Look at one half of that parallelogram as a triangle:
shortening the "hypotenuse" (for brevity - you know what I mean) by a
constant amount per click would not give a constant sideways motion.

So, are the clicks in a shifter then non-uniform in the amount of cable
they pull? Or are the sprockets not uniform in spacing? Or is there
something I'm not seeing?

Quoted message said:

Getting back to cable pull: Apparently, the sprocket spacing (or
sprocket pitch) is uniform across the cassette. Seems to me, then,
that the cable pull can't be exactly uniform across all the shifter's
clicks. IOW, the "shift ratio" in
http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3946 can't be a
constant.

I say this because the cable acts as a diagonal to the derailleur's
parallelogram. Look at one half of that parallelogram as a triangle:
shortening the "hypotenuse" (for brevity - you know what I mean) by a
constant amount per click would not give a constant sideways motion.

So, are the clicks in a shifter then non-uniform in the amount of cable
they pull? Or are the sprockets not uniform in spacing? Or is there
something I'm not seeing?

You're right. Years ago I (imprecisely) measured Dura-Ace 8 speed and
found clearly uneven steps in cable pull. Unfortunately I don't have
the numbers any more.

Quoted message said:

Getting back to cable pull: Apparently, the sprocket spacing (or
sprocket pitch) is uniform across the cassette. Seems to me, then,
that the cable pull can't be exactly uniform across all the shifter's
clicks. IOW, the "shift ratio" in
http://www.ctc.org.uk/DesktopDefault.aspx?TabID=3946 can't be a
constant.

I say this because the cable acts as a diagonal to the derailleur's
parallelogram. Look at one half of that parallelogram as a triangle:
shortening the "hypotenuse" (for brevity - you know what I mean) by a
constant amount per click would not give a constant sideways motion.

So, are the clicks in a shifter then non-uniform in the amount of cable
they pull? Or are the sprockets not uniform in spacing? Or is there
something I'm not seeing?

I think you have it - just fill in the last blank.
The cassette cogs are evenly spaced. The indexing 'cam' (
the slotted steel thing the springs snap into when shifting)
has progressively wider spaces, as you go toward low, to
compensate for the reduced lateral movement inherent to the
changed leverage as the parallelogram deforms.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971