Shimano rear derailer compatibility

"David Favro" wrote in message
om...
Hello all --

I know this is a FAQ, but there are so many permutations, it gets
confusing...

I am trying to replace my rear derailer, and I'm worried about
compatibility. I'm switching from a "road" to a "mountain" derailer
because the "road" lines can't handle the spread of gear-teeth that I
need, even though my bicycle is ostensibly a "road" bike (I never
could understand the distinction).

My current set-up:
Shifter: Shimano RSX ("7-speed")
Derailer: Shimano RSX ("7-speed")
Rear cogs: Shimano Hyperglide 7-speed

I'm considering getting the Shimano Deore LX rear derailer or perhaps
Deore XT. According to Sheldon Brown's web-site (
http://www.sheldonbrown.com/dura-ace.html#indexing and
http://www.sheldonbrown.com/harris/d...ar.html#speeds ), it
appears to me that they should be compatible, but the catalog where I
saw them advertised calls the "Deore" "8/9-speed compatible," and the
"Deore LX" and "Deore XT" ones "9-speed compatible". The fact that
they specifically mention 8-speed on the Deore but not on the others
implies that the LX & XT are *not* compatible with 8-speed, let alone
my 7-speed cogs and shifters. I'm guessing that they're lying, but
can anyone confirm that for me before I mail-order something that
doesn't work and I have to pay return postage?


I've recently upgraded my old 27" department store 'ten speed' with a
7-speed 14-34 freewheel and a Deore LX rear derailer. For no good reason, I
occasionally swap between straight bars with 'old' Deore DX 7-speed
shifters, and drop bars with Sora 7-speed 'brifters'. I have absolutely no
indexing problems with either combination.

On 20 Jun 2004 07:48:13 -0700, (David Favro) wrote:


I'm considering getting the Shimano Deore LX rear derailer or perhaps
Deore XT. According to Sheldon Brown's web-site (
http://www.sheldonbrown.com/dura-ace.html#indexing and
http://www.sheldonbrown.com/harris/d...ar.html#speeds ), it
appears to me that they should be compatible, but the catalog where I
saw them advertised calls the "Deore" "8/9-speed compatible," and the
"Deore LX" and "Deore XT" ones "9-speed compatible". The fact that
they specifically mention 8-speed on the Deore but not on the others
implies that the LX & XT are *not* compatible with 8-speed, let alone
my 7-speed cogs and shifters. I'm guessing that they're lying,

Lying isn't what they would call it. They are probably basing these
kind of statements on what they still make in each line and what they
can expect others to do with their parts. Last spring I bought a bike
that had a Deore RD and it was 8 speed. Even though the derailleur had
'mega 9' on it.

There are lags between what is the newest and what is still available.
On lower end bikes like the one I bought, using older parts (8 speed)
reduces costs and helps everyone get rid of old inventory.

LX and XT are more 'upscale' lines. No sense mentioning 7 or 8 speed
because they won't be used on new bikes at this price point most
likely. And Shimano wants the kind of people who buy XT to throw out
all any and all old stuff that isn't '9-speed.' They have a lot of
tooling and setup costs to recoup!!

The XT rear derailleur is very nice. Haven't used the LX. And I have
used the 9 speed XT on 7 speeds with no problems, a 7 speed XT on 9,
an 8 speed on 9, and even an 8 speed on 8 and 9 on 9- all worked fine.

On 20 Jun 2004 07:48:13 -0700, (David Favro) wrote:

My current set-up:
Shifter: Shimano RSX ("7-speed")
Derailer: Shimano RSX ("7-speed")
Rear cogs: Shimano Hyperglide 7-speed

I'm considering getting the Shimano Deore LX rear derailer or perhaps
Deore XT. According to Sheldon Brown's web-site (
http://www.sheldonbrown.com/dura-ace.html#indexing and
http://www.sheldonbrown.com/harris/d...ar.html#speeds ), it
appears to me that they should be compatible, but the catalog where I
saw them advertised calls the "Deore" "8/9-speed compatible," and the
"Deore LX" and "Deore XT" ones "9-speed compatible".

They all use the same indexing-compatible movement ratios, and can be
freely interchanged as long as they're used with a cassette that's
within their capacity. There is widespread suspicion that the lack of
implied 7/8/9 compatibility is a marketing ploy to get people to buy
components that they don't really need.

I don't think it's related, but my rear cogs are currently 11-30 (I
want to make that 32 or 34) and my front set-up is a Shimano
105-triple derailer, 24-46 cogs (I'd like to make that granny a 22),
and Shimano RSX shifter.

I think the 22 might cause the chain to rub the bar on a 105,
particularly if you're running on the smaller half of the rear
cassette. You might take a look at how much clearance you have there
now. There are MTB front ders which can solve this if it's a problem,
though I suspect that if you go to a 34 bailout on the rear, you may
find that there's no need to drop to a 22 on the front.

David Favro wrote:

.......... I'm guessing that they're lying, but
can anyone confirm that for me before I mail-order something that
doesn't work and I have to pay return postage?

I have used the same XT rear mech with 6 (uniglide) and 9 (hyperglide)
cassettes on the same road bike. The shifters determine the throw of the
mech which of course must match the spacings in the sprockets. I used
Shimano 105 six speed downtube shifters and Dura Ace 9 speed ones. My
cassettes are 14-32 in six and a custom 12-32 in 9. Setup of the 9 speed was
more fiddley but this was due to a less than perfectly aligned hanger.

David Favro wrote:

I know this is a FAQ, but there are so many permutations, it gets
confusing...

It becomes less confusing if you ignore the marketing hype.

I am trying to replace my rear derailer, and I'm worried about
compatibility. I'm switching from a "road" to a "mountain" derailer
because the "road" lines can't handle the spread of gear-teeth that I
need, even though my bicycle is ostensibly a "road" bike (I never
could understand the distinction).
=20
My current set-up:
Shifter: Shimano RSX ("7-speed")
Derailer: Shimano RSX ("7-speed")
Rear cogs: Shimano Hyperglide 7-speed

Any Shimano or Shimano-type rear derailer made since 1997 will be=20
compatible with these. No exceptions.

Sheldon "Easier Than You Think" Brown
Bristol, U.K.
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dfavro- My current set-up:
Shifter: Shimano RSX ("7-speed")
Derailer: Shimano RSX ("7-speed")
Rear cogs: Shimano Hyperglide 7-speed BRBR
I'm considering getting the Shimano Deore LX rear derailer or perhaps
Deore XT. According to Sheldon Brown's web-site BRBR


Sheldon is correct, Use any shimano MTB rear der w/o problem or issue.

dfavro- but the catalog where I
saw them advertised calls the "Deore" "8/9-speed compatible," and the
"Deore LX" and "Deore XT" ones "9-speed compatible". The fact that
they specifically mention 8-speed on the Deore but not on the others
implies that the LX & XT are *not* BRBR

They are compatible. Web sites and catalogs are notorious for being misleading
or just being ignorant of what works and doesn't.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

Thanks to all who responded... I ordered the derailer, I think it will
work.

--
David Favro
Please post replies to newsgroup, I am likely to lose your response in the
torrent of spam.