which derailleur?

Trevor said:

Hi ppl,

I have a derailleur on a 7spd cassette which I want to replace.
The guy at a LBS seemed to think that a later model derailleur (8/9
speed etc) would not work with 7spd cassette.

As far as I can tell, 'index shifting' is done by the mechanics at the
handlebars, and the derailleur is more-or-less 'passive'.
Can someone advise me please.

Thanks,
Trev

I'm pretty sure it would work. The jockey wheels would be a tiny bit smaller with 9sp, but I think it would work. As you say, the derailleur is passive. Indexing is what shifters are for...

Ritch.

"ritcho" <[email hidden]

Quoted message said:

Quoted message said:

I have a derailleur on a 7spd cassette which I want to replace.
The guy at a LBS seemed to think that a later model derailleur (8/9
speed etc) would not work with 7spd cassette.

I'm pretty sure it would work. The jockey wheels would be a tiny bit
smaller with 9sp, but I think it would work. As you say, the derailleur
is passive. Indexing is what shifters are for...

But why would you want to fit a typically more
expensive 9spd derr. when you can fit a cheaper
7/8spd one?

hippy

"ritcho" <[email hidden]

Quoted message said:

Quoted message said:

I have a derailleur on a 7spd cassette which I want to replace.
The guy at a LBS seemed to think that a later model derailleur (8/9
speed etc) would not work with 7spd cassette.

I'm pretty sure it would work. The jockey wheels would be a tiny bit
smaller with 9sp, but I think it would work. As you say, the derailleur
is passive. Indexing is what shifters are for...

But why would you want to fit a typically more
expensive 9spd derr. when you can fit a cheaper
7/8spd one?

hippy

[email hidden] (Trevor) wrote in news:b27e0af4.0410041635.2a12cc5
@posting.google.com:

Quoted message said:

As far as I can tell, 'index shifting' is done by the mechanics at the
handlebars, and the derailleur is more-or-less 'passive'.
Can someone advise me please.

Someone on ebay was selling a Positron derailleur the other week, mind
you...

--
to email me, run my email address through /usr/bin/caesar
(or rotate by -4)

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

Quoted message said:

Trevor said:

Hi ppl,

I have a derailleur on a 7spd cassette which I want to replace.
The guy at a LBS seemed to think that a later model derailleur (8/9
speed etc) would not work with 7spd cassette.

As far as I can tell, 'index shifting' is done by the mechanics at the
handlebars, and the derailleur is more-or-less 'passive'.
Can someone advise me please.

Thanks,
Trev

I agree with you, and the other posters. 7/8 cog cassettes have
different "click" distances from 9/10 cog cassettes, but this only goes
for the shifters and cassette. (Yes, yes, I know the 9/10 chain is
narrower than the 7/8 chain.) A frozen-in-carbonite mint-condition
(even maybe drilled-out) SunTour Cyclone rear derailleur from 1983 will
respond just as well as well as the 2005 gruppo thingo

....only if you are able to rig up some sort of cable barrel-adjuster to
attach onto it. Pre-index derailleurs generally just led the cable-housing
straight into the derailleur. The only adjustment to cable tension was by
undoing the cable anchor.

Cheers
Peter

Trevor said:

Hi ppl,

I have a derailleur on a 7spd cassette which I want to replace.
The guy at a LBS seemed to think that a later model derailleur (8/9
speed etc) would not work with 7spd cassette.

As far as I can tell, 'index shifting' is done by the mechanics at the
handlebars, and the derailleur is more-or-less 'passive'.
Can someone advise me please.

Thanks,
Trev

I agree with you, and the other posters. 7/8 cog cassettes have
different "click" distances from 9/10 cog cassettes, but this only goes
for the shifters and cassette. (Yes, yes, I know the 9/10 chain is
narrower than the 7/8 chain.) A frozen-in-carbonite mint-condition
(even maybe drilled-out) SunTour Cyclone rear derailleur from 1983 will
respond just as well as well as the 2005 gruppo thingo your LBS wants
you to buy.
We miss, you, SunTour ;-) !
[censored]
ppp