more indexing questions

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

Quoted message said:

ok, here goes ...

I'm confused again. I thought I'd understood all the issues with camapg/shimano indexing
compatabilitiy.

But maybe I'm overthinking or underthinking or something ...... (deep breath) ....

You can use a Shimano 9 sp cassette with a campag 9 spd derailleur using campag 9 speed shifters.
So far so good.

But, since the derailleur itself is not "indexed", and the levers do the work, and it IS a shimano
hub, WHY doesn't a shimano rear derailleur just "work". Surely the shifting distances are the same
since its the same hub.

The rear changer is a paralellogram that translates wire pull across the corners into a lateral
motion at the cage. The ratio of cable movement in to cage travel out is not identical. That's
the reason that switching the wire to the "wrong" side allows some changers to work where they
were not intended. That changes the leverage of the wire and therefore the ratio of wire travel
to cage travel.

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

Walter Mitty-<< You can use a Shimano 9 sp cassette with a campag 9 spd derailleur using campag 9
speed shifters. So far so good.

But, since the derailleur itself is not "indexed", and the levers do the work, and it IS a shimano
hub, WHY doesn't a shimano rear derailleur just "work". Surely the shifting distances are the same
since its the same hub.

I know this is going to be glaringly obvious.

The amount the rear der moves for each 'click' is determined by the diameter of the barrell the
cable is being wrapped around in the shifter and the dimension of the rear der. If these were the
same shimano and Campagnolo, they would be cross compatible but they are not.

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 vecchios.comvecchios.comOpen ↗ "Ruote convenzionali costruite eccezionalmente bene"