9 speed rear derailleur - 8 speed shifters & cassette

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9 speed rear derailleur - 8 speed shifters & cassette

Postby pembo6 » Mon Sep 17, 2012 5:06 pm

Is there any reason a new 9 speed rear derailleur wont work with existing 8 speed rear cassette and 8 speed shifter?

I need to replace my dead shimano sora rear derailleur and was going to get a new 9 speed sora (they dont make 8 speed anymore). Can't justify a whole upgrade to 9 or 10 speed.

I don't see any reason why It wouldn't work perfectly. Unless the teeth on the pulley wheels are a different size and damage the 8 speed chain.

Can anyone confirm? Thanks.
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by BNA » Mon Sep 17, 2012 7:15 pm

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Re: 9 speed rear derailleur - 8 speed shifters & cassette

Postby Velo13 » Mon Sep 17, 2012 7:15 pm

Should work just fine.
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Re: 9 speed rear derailleur - 8 speed shifters & cassette

Postby funnybike » Tue Sep 18, 2012 11:02 am

The only reason it won't work is if your 8 speed shifters are the 7400 series Dura Ace. They have a different amount of cable pull and will only work with the matching derailleur. If it is any other shimano model, then it will work perfectly with the 9 speed rear derailleur.
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Re: 9 speed rear derailleur - 8 speed shifters & cassette

Postby jules21 » Tue Sep 18, 2012 12:28 pm

pembo6 wrote:Is there any reason a new 9 speed rear derailleur wont work with..

the only thing that counts is the pull ratio. there is no such thing as a "9 spd derailleur", that is just marketing spin.
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Re: 9 speed rear derailleur - 8 speed shifters & cassette

Postby bosvit » Tue Sep 18, 2012 1:29 pm

jules21 wrote:
pembo6 wrote:Is there any reason a new 9 speed rear derailleur wont work with..

the only thing that counts is the pull ratio. there is no such thing as a "9 spd derailleur", that is just marketing spin.

+1

I've been running 9 speed vitamin a, b, c, d and e rd with 8 speed sofa shifters for years. They came stock on my Trek 1000.
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Re: 9 speed rear derailleur - 8 speed shifters & cassette

Postby Mustang » Tue Sep 18, 2012 7:01 pm

I have run a 9 sp.,105 long cage Shimano 105 RD, with a 6 speed cassette, on my Vitus.
Its the shifter that does the work, the extra travel can be limited by the stop screws.
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Re: 9 speed rear derailleur - 8 speed shifters & cassette

Postby pembo6 » Wed Sep 19, 2012 5:52 pm

Interesting....

I have been informed by Shimano Australia, Wiggle & ChainReaction that the 9sp rear derailleur will not work properly in place of the 8sp.

But I bought one new anyway, for $13.50 ......so who cares!

I bet it works just fine.

Thanks for the answers you posted.
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Re: 9 speed rear derailleur - 8 speed shifters & cassette

Postby rifraf » Sun Sep 23, 2012 3:53 pm

pembo6 wrote:Interesting....

I have been informed by Shimano Australia, Wiggle & ChainReaction that the 9sp rear derailleur will not work properly in place of the 8sp.

But I bought one new anyway, for $13.50 ......so who cares!

I bet it works just fine.

Thanks for the answers you posted.

I use a 9 speed XT M772 derailleur on a 7 speed cassette.
However I do believe some 9 speed XT derailleurs only suited narrow 9 speed chains.
I saw this mentioned on the Wiggle site and based my purchase decision on it.
My XT derailleur was backwards compatible but apparently not all are:
Wiggle describes the M770 as: "Mega9 compatible for use with 9-speed drivetrains"
M771 as: "Mega9 compatible for use with 9-speed drivetrains"
Wiggle describes the M780 as: "Dyna-Sys 10-speed compatible only"
M780 Shadow as: "MTB 10-speed compatible only"

Wiggle describes My M772 as: "Mega9, 8 & 7 speed compatible"

Hope this helps :)
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Re: 9 speed rear derailleur - 8 speed shifters & cassette

Postby rifraf » Sun Sep 23, 2012 3:56 pm

jules21 wrote:
pembo6 wrote:Is there any reason a new 9 speed rear derailleur wont work with..

the only thing that counts is the pull ratio. there is no such thing as a "9 spd derailleur", that is just marketing spin.

I believe this is not entirely correct.
The fact that some do creates confusion.
See my other post to clarify. :)

It comes down to the spread of the derailleur as to whether the thicker (lower speed) chains will
travel through the cage.
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