# Shimano Rear Derailleur Cable Pull Ratios



## Lelandjt (Sep 11, 2008)

Did the cable pull ratio change on Shimano's road rear derailleurs when they went from 9 to 10spd? Can a 10spd Dura-ace 7800 rear derailleur be used on an otherwise 9spd Dura-ace 7700 drivetrain? The old mechanic at my shop says no, the ratio changed. A little quick Googling seems to say Shimano 9&10spd derailleurs are interchangable. Shimano mountain and road 8 & 9spd were all compatible with a 2:1 ratio.
My 7700 derailleur is dying and I can have a free 7800 if it works.

This info would also be useful for situations where a roadie customer wants to put a 32 or 34 cassette on their Shimano 10spd bike. Shimano road derailleurs aren't made for that big a cog and I know Shimano mountain 10spd derailleurs (1.21:1 ratio) aren't compatible but if a 9spd road derailleur is than a 9spd mtn would be.


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## cxwrench (Nov 9, 2004)

Lelandjt said:


> Did the cable pull ratio change on Shimano's road rear derailleurs when they went from 9 to 10spd? Can a 10spd Dura-ace 7800 rear derailleur be used on an otherwise 9spd Dura-ace 7700 drivetrain? The old mechanic at my shop says no, the ratio changed. A little quick Googling seems to say Shimano 9&10spd derailleurs are interchangable. Shimano mountain and road 8 & 9spd were all compatible with a 2:1 ratio.
> My 7700 derailleur is dying and I can have a free 7800 if it works.
> 
> This info would also be useful for situations where a roadie customer wants to put a 32 or 34 cassette on their Shimano 10spd bike. Shimano road derailleurs aren't made for that big a cog and I know Shimano mountain 10spd derailleurs (1.21:1 ratio) aren't compatible but if a 9spd road derailleur is than a 9spd mtn would be.


you work at a shop, yeah? haven't you ever seen a shimano compatibility chart? the 7800 will work, your mechanic is ill-informed.


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## Lelandjt (Sep 11, 2008)

Thanks, never seen the chart. I didn't work at shops between 2002 and 2012 and wasn't paying attention to road parts during the years that Shimano changed their road stuff to 10spd.

As a fellow wrench you might dig this craziness, I'm trying it in a few days when my Shadow+ derailleur arrives: Changing Shimano 10spd MTN cable pull from 1.21:1 to 1:1 for compatibility with Sram 8 & 9spd shifters using a 6mm spacer. This allows 9spd owners to use a clutch which is awesome and just opens the door to more derailleur availability when in a pinch. 6mm worth of spacers is easy to assemble if there's random washers around.









Since we're talking ratios what is Sram road 10spd cable pull? The same as their mountain 10spd at about .8:1, right? What's the Shimano 11spd cable pull?


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## ziscwg (Apr 19, 2010)

to you last comment about 32 cassettes.
You need a 9 speed mtn RD (shimano) to work with the STI shifters. There are still plenty of XT and XTR RD out there. Mid cage will do 32 cassettes fine. If you want to go to 34, get a long cage. They are more availible anyway.

SRAM is a different animal all together. No mixing of 9 and 10 speed parts at all. So, your 10 spd X.9 works fine with your Force shifters. If anyone tells you different, have them come and ride my bike. They will need to bring their own fork to eat crow though.


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## cxwrench (Nov 9, 2004)

Lelandjt said:


> Thanks, never seen the chart. I didn't work at shops between 2002 and 2012 and wasn't paying attention to road parts during the years that Shimano changed their road stuff to 10spd.
> 
> As a fellow wrench you might dig this craziness, I'm trying it in a few days when my Shadow+ derailleur arrives: Changing Shimano 10spd MTN cable pull from 1.21:1 to 1:1 for compatibility with Sram 8 & 9spd shifters using a 6mm spacer. This allows 9spd owners to use a clutch which is awesome and just opens the door to more derailleur availability when in a pinch. 6mm worth of spacers is easy to assemble if there's random washers around.
> 
> ...


that sounds cool, lemme know how it works. SRAM is totally compatible across road/mtb. 11spd Shimano? i have no idea what the cable pull is, i'd have to measure it...
good luck w/ your project!


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## MR_GRUMPY (Aug 21, 2002)

Everything should work fine between Road 8.9.10 (except DA 8), and MTN 8,9. 
Road 11 is slightly different, and MTN 10 is different.
The only problem that you Might have is pulley width. (if you have a 10 speed derailleur on a 8 speed cogset, you might have to use a 9 speed chain....)

Correct me if I am wrong.
.
.


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## Lelandjt (Sep 11, 2008)

MR_GRUMPY said:


> Everything should work fine among Road 8.9.10 (except DA 8), and MTN 8,9.


What's the story with DA 8 being different? The "old mechanic" at my shop said something about that but I don't remember any differences among Shimano's 8 speed groups.


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## MR_GRUMPY (Aug 21, 2002)

DA 7 & 8 had a different pull than Ultegra 7,8,9,10. When Shimano came out with DA 9 (7700) they made the derailleur, and shifters compatable with other Shimano products.
.


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