Ergo 10s and Shimano 8s compatability

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

Quoted message said:

Hi everyone, this'll be my first post. It concerns an article I found

Quoted message said:

Basically, I'm interested in running Ergo levers (9s or 10s, whichever
work) with a Sram/Sachs Di.R.T. rear derailleur (Shimano compatible)
and a modern 8s Sram mountain cassette. It looks by the article that I
came across that 10s Ergos should do the trick.

Let's see: Campy 10-speed is 4.12mm cog center to center. The latest Campy
derailleurs have a mechanical advantage of 1.5 to 1. Therefore, Campy
10-speed shifters pull 2.75 mm of cable per click.

Using a Shimano-compatible rear derailleur (advantage of 1.67 to 1) will
result in 4.58 mm of derailleur travel per click. Shimano 8-speed cassettes
are spaced at 4.8mm cog center to center.

Fairly close. Worst case: file some of the spacers in the cassette down
with sandpaper so they are thinner. Use a 9-speed chain.

hmmmm...I see. I guess that's not the "it'll shift perfectly!" news I
was hoping for. The article seemed to make the argument that Campy 10s
shifters pull the same amount of cable per shift as Shimano 8s
shifters. Does that amount of cable per shift change over the range of
shifting (I don't have either Campy 10s or Shimano 8s shifters at the
moment to try to verify this)? And similarly, do derailleurs have a
constant mechanical advantage, as both you and the article imply (I've
looked at my Sram derailleur to try and figure this out, but I'm having
a hard time visualizing it without it in working condition on a bike)?
How much would this affect the outcome of a calculation like that? Is
an average like the one you did (if, indeed, it is an average) a good
enough approximation? I don't know if anyone, even the people who
wrote the article, have really looked into this at this kind of depth.
The article has very precise specs for the spacing between cogs,
not-very-precise-at-all specs for the amount of cable per shift,
not-very-precise specs for the derailleur mechanical advantage, and
they turn all that into very precise specs for the final shifting
pitch. Is this bologna? What does everyone think would be the best
approach to this problem?

Also, David, the numbers you used in your calculation differ somewhat
from the numbers in the article, specifically Campy 10s cassette
spacing and Shimano derailleur mechanical advantage. Could you tell me
where you got your specs from? And thank you for responding.

Quoted message said:

I don't know if anyone, even the people who
wrote the article, have really looked into this at this kind of depth.

I think you will find the people you refer to are in fact one person,
Chris Juden, who is the CTC's Technical Officer. If you want to know
more, read some more on the CTC site or put his name into Google.

Quoted message said:

The article has very precise specs for the spacing between cogs,
not-very-precise-at-all specs for the amount of cable per shift,
not-very-precise specs for the derailleur mechanical advantage, and
they turn all that into very precise specs for the final shifting
pitch. Is this bologna?

Isn't that it Italy someplace near ancient Campagnolatium?

Better wait till you get some proper advice from this group. You can be
sure everything you read here, on this newsgroup is authentic and well
researched and that it always avoids unnecessary abrasive language, long
standing personal feuding, sarcasm and is most importantly 100% home
grown American.

Well, perhaps not always.
--

Martyn Aldis, e-mail [email hidden]
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