Rear derailleur compatibility

I have a 12 year old mountain bike with a worn out Deore DX rear derailleur.
My drivetrain is 7-speed -- can I replace the derailleur with one from an 8
or 9-speed drivetrain?

Basically it boils down to this -- is the index spacing of 8 and 9-speed
drivetrains the same as the index spacing on a 7-speed? If so then I
should be fine.

If anyone has information on replacement derailleur compatibility it
would be appreciated. Please reply to me directly and I will summarize
to the list.

Many thanks!
Yggy

On Thu, 07 Oct 2004 04:41:03 GMT, "Yggy King" wrote:

I have a 12 year old mountain bike with a worn out Deore DX rear derailleur.
My drivetrain is 7-speed -- can I replace the derailleur with one from an 8
or 9-speed drivetrain?

Basically it boils down to this -- is the index spacing of 8 and 9-speed
drivetrains the same as the index spacing on a 7-speed? If so then I
should be fine.

If anyone has information on replacement derailleur compatibility it
would be appreciated. Please reply to me directly and I will summarize
to the list.

Many thanks!
Yggy

Only the shift lever is indexed so almost any derailleur will shift 7
speed cogs if you set the limit screwws correctly. The pivot points
on the derailleur wear out over time so finding a derailleur that uses
good bushings at the pivot points would probably last longer. The
cheapest Shimano tourney series derailleurs for example seem to wear
out after only one set of jockey wheels but that is still over 15,000
miles of road use.

On Thu, 07 Oct 2004 04:41:03 GMT, "Yggy King" wrote:

I have a 12 year old mountain bike with a worn out Deore DX rear derailleur.
My drivetrain is 7-speed -- can I replace the derailleur with one from an 8
or 9-speed drivetrain?

Basically it boils down to this -- is the index spacing of 8 and 9-speed
drivetrains the same as the index spacing on a 7-speed? If so then I
should be fine.

If anyone has information on replacement derailleur compatibility it
would be appreciated. Please reply to me directly and I will summarize
to the list.

Many thanks!
Yggy

Only the shift lever is indexed so almost any derailleur will shift 7
speed cogs if you set the limit screwws correctly. The pivot points
on the derailleur wear out over time so finding a derailleur that uses
good bushings at the pivot points would probably last longer. The
cheapest Shimano tourney series derailleurs for example seem to wear
out after only one set of jockey wheels but that is still over 15,000
miles of road use.

"Yggy King" wrote in message news:zN39d.12419$a41.2206@pd7tw2no...
I have a 12 year old mountain bike with a worn out Deore DX rear derailleur.
My drivetrain is 7-speed -- can I replace the derailleur with one from an 8
or 9-speed drivetrain?

Basically it boils down to this -- is the index spacing of 8 and 9-speed
drivetrains the same as the index spacing on a 7-speed? If so then I
should be fine.

If anyone has information on replacement derailleur compatibility it
would be appreciated. Please reply to me directly and I will summarize
to the list.

Many thanks!
Yggy

I just replaced my 1991 Deore DX 7 speed derailleur on my touring
bike. It came from a 1991 Trek 520 with bar end index shifters. It
would not clear a 34 tooth cog on my new Redline touring frame. So I
replaced it with a brand new 9 speed Deore derailleur. The cheap $20
black one. Still using the same 7 speed cassette and 7 speed index
bar end shifters. Works just fine. And it clears the 34 tooth cog
easily. All Shimano derailleurs, except Dura Ace until the late
1990s, were interchangeable among brands and number of gears, 7-8-9.

"Yggy King" wrote in message news:zN39d.12419$a41.2206@pd7tw2no...
I have a 12 year old mountain bike with a worn out Deore DX rear derailleur.
My drivetrain is 7-speed -- can I replace the derailleur with one from an 8
or 9-speed drivetrain?

Basically it boils down to this -- is the index spacing of 8 and 9-speed
drivetrains the same as the index spacing on a 7-speed? If so then I
should be fine.

If anyone has information on replacement derailleur compatibility it
would be appreciated. Please reply to me directly and I will summarize
to the list.

Many thanks!
Yggy

I just replaced my 1991 Deore DX 7 speed derailleur on my touring
bike. It came from a 1991 Trek 520 with bar end index shifters. It
would not clear a 34 tooth cog on my new Redline touring frame. So I
replaced it with a brand new 9 speed Deore derailleur. The cheap $20
black one. Still using the same 7 speed cassette and 7 speed index
bar end shifters. Works just fine. And it clears the 34 tooth cog
easily. All Shimano derailleurs, except Dura Ace until the late
1990s, were interchangeable among brands and number of gears, 7-8-9.

On 7 Oct 2004 08:46:43 -0700, (Russell
Seaton) wrote:

"Yggy King" wrote in message news:zN39d.12419$a41.2206@pd7tw2no...
I have a 12 year old mountain bike with a worn out Deore DX rear derailleur.
My drivetrain is 7-speed -- can I replace the derailleur with one from an 8
or 9-speed drivetrain?

Basically it boils down to this -- is the index spacing of 8 and 9-speed
drivetrains the same as the index spacing on a 7-speed? If so then I
should be fine.

If anyone has information on replacement derailleur compatibility it
would be appreciated. Please reply to me directly and I will summarize
to the list.

Many thanks!
Yggy

I just replaced my 1991 Deore DX 7 speed derailleur on my touring
bike. It came from a 1991 Trek 520 with bar end index shifters. It
would not clear a 34 tooth cog on my new Redline touring frame. So I
replaced it with a brand new 9 speed Deore derailleur. The cheap $20
black one. Still using the same 7 speed cassette and 7 speed index
bar end shifters. Works just fine. And it clears the 34 tooth cog
easily. All Shimano derailleurs, except Dura Ace until the late
1990s, were interchangeable among brands and number of gears, 7-8-9.

You are probably smart staying with the 7 speed cassette. When I
changed from 6 to 7 speed freewheels I gained a little over 3 mm's of
cluster width. Now the smallest cog on the freewheel has a poorer
chain line than it did on a 6 speed cluster. My 16 tooth and 18 tooth
sprockets run smooth so I'm not complaining. The 16 / 52 combination
gets me to 23 mph which is plenty fast. Replacement parts are very
economical for 7 speed setups for sure, rugged 7 speed chain costs a
lot less than that narrow stuff!

On 7 Oct 2004 08:46:43 -0700, (Russell
Seaton) wrote:

"Yggy King" wrote in message news:zN39d.12419$a41.2206@pd7tw2no...
I have a 12 year old mountain bike with a worn out Deore DX rear derailleur.
My drivetrain is 7-speed -- can I replace the derailleur with one from an 8
or 9-speed drivetrain?

Basically it boils down to this -- is the index spacing of 8 and 9-speed
drivetrains the same as the index spacing on a 7-speed? If so then I
should be fine.

If anyone has information on replacement derailleur compatibility it
would be appreciated. Please reply to me directly and I will summarize
to the list.

Many thanks!
Yggy

I just replaced my 1991 Deore DX 7 speed derailleur on my touring
bike. It came from a 1991 Trek 520 with bar end index shifters. It
would not clear a 34 tooth cog on my new Redline touring frame. So I
replaced it with a brand new 9 speed Deore derailleur. The cheap $20
black one. Still using the same 7 speed cassette and 7 speed index
bar end shifters. Works just fine. And it clears the 34 tooth cog
easily. All Shimano derailleurs, except Dura Ace until the late
1990s, were interchangeable among brands and number of gears, 7-8-9.

You are probably smart staying with the 7 speed cassette. When I
changed from 6 to 7 speed freewheels I gained a little over 3 mm's of
cluster width. Now the smallest cog on the freewheel has a poorer
chain line than it did on a 6 speed cluster. My 16 tooth and 18 tooth
sprockets run smooth so I'm not complaining. The 16 / 52 combination
gets me to 23 mph which is plenty fast. Replacement parts are very
economical for 7 speed setups for sure, rugged 7 speed chain costs a
lot less than that narrow stuff!

Yggy King wrote:

I have a 12 year old mountain bike with a worn out Deore DX rear derailleur.
My drivetrain is 7-speed -- can I replace the derailleur with one from an 8
or 9-speed drivetrain?

Yes, there's no problem with this.

Basically it boils down to this -- is the index spacing of 8 and 9-speed
drivetrains the same as the index spacing on a 7-speed?

No, but that is a matter to be determined by the shifter and the
cassette. The derailer doesn't care how many gears there are.

Virtually all Shimano rear derailers index the same and can be
interchanged among different numbers of speeds.

Sheldon "No Problem" Brown
+------------------------------------------------+
| If you don't want your message to get to me, |
| insert **NO-SPAM** into my email address. |
+------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Yggy King wrote:

I have a 12 year old mountain bike with a worn out Deore DX rear derailleur.
My drivetrain is 7-speed -- can I replace the derailleur with one from an 8
or 9-speed drivetrain?

Yes, there's no problem with this.

Basically it boils down to this -- is the index spacing of 8 and 9-speed
drivetrains the same as the index spacing on a 7-speed?

No, but that is a matter to be determined by the shifter and the
cassette. The derailer doesn't care how many gears there are.

Virtually all Shimano rear derailers index the same and can be
interchanged among different numbers of speeds.

Sheldon "No Problem" Brown
+------------------------------------------------+
| If you don't want your message to get to me, |
| insert **NO-SPAM** into my email address. |
+------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com