# Rear derailleur for 9-speed 11-34T cassette and 105 STI shifters



## Brownie0629 (Jul 5, 2014)

Looking for some expert advise here. I am riding a 2006 LeMond Versailles Triple with 9-speed Shimano 105 STI shifters and Ultegra rear derailleur. I recently moved from Florida to Okinawa, Japan and decided I needed to upgrade the rear cassette from a SRAM 12-26T to SRAM 11-34T to help with the hills here. The upgrade works but its not ideal with the Ultegra RD (I think its a RD-6500-GS). Just a little beyond the capacity of the Ultegra - can't handle the ideal chain length and not enough clearance between the guide pulley and the 34T cog.

Researched old threads and it sounds like I need to use a 9-speed long cage MTB derailleur to be compatible with the 9-speed 105 STI shifters. I came up with a Shimano XT M771 SGS 9-Speed RD as being a good candidate for replacing the Ultegra RD and its widely available. Most other new MTB shifters are 10-speed and are not compatible with my 9-speed STI shifters, so I am told.

I'd appreciate any advice from others who have much more experience than I do if the XT M771 SGS RD is a good choice or should I consider something else. Thanks for your help.


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## frdfandc (Nov 27, 2007)

The XT RD will work just fine. Don't forget a new chain as well. Or if you want to save a couple of bucks, try to find an SLX 9 speed RD.


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## ghettocop (Apr 19, 2014)

The new 105 long cages will handle 34 as well, if you want to stay with road group.


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## tihsepa (Nov 27, 2008)

ghettocop said:


> The new 105 long cages will handle 34 as well, if you want to stay with road group.


The cage dosent have anything to do with what cassette it can handle. 
Cage length is only for chain wrap not large cassette cog.


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## Brownie0629 (Jul 5, 2014)

Thanks for the quick reply. So SLX is the next step down from XT?


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## Brownie0629 (Jul 5, 2014)

I was going with the XT RD because I though this would be roughly equivalent to my Ultegra RD thinking that XT was the step down from next XTR and Ultegra was the next step down from Dura Ace. I can order the XT online for only $20-$25 more than the SLX but the XTR is like another $100. I don't really have the personal experience to know but most roadies online seem to be pretty happy with Ultegra and don't think to think the benefits of Dura Ace over Ultegra are very great. I was thinking the same might be hold for XTR over XT.


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## tednugent (Apr 26, 2010)

frdfandc said:


> The XT RD will work just fine. Don't forget a new chain as well. Or if you want to save a couple of bucks, try to find an SLX 9 speed RD.


Does a 9-speed shimano MTB rear derailleur work with 9-speed road shifters?

My 10-speed 105 shifter is mated to a 9-speed XT rear derailleur


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## ghettocop (Apr 19, 2014)

tihsepa said:


> The cage dosent have anything to do with what cassette it can handle.
> Cage length is only for chain wrap not large cassette cog.


I understand this. The new 105 long cage will handle a34 tooth cog without resorting to crazy B screw manipulation. I have customers using this set up with success. It gives an alternative to WiFli or MTB stuff.


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## Brownie0629 (Jul 5, 2014)

I went to Shimano's website and best I can tell is that the 105 and Ultegra RDs are only available in a medium cage GS (and a short cage SS), but no long cage SGS. Only the Mountain RDs seem to come in SGS long cages. Seems strange to me that Shimano does not produce SGS long cage versions for road touring where climbing and climbing with a load requires the larger cogs (at least for us non-pro's)


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## ghettocop (Apr 19, 2014)

Brownie0629 said:


> I went to Shimano's website and best I can tell is that the 105 and Ultegra RDs are only available in a medium cage GS (and a short cage SS), but no long cage SGS. Only the Mountain RDs seem to come in SGS long cages. Seems strange to me that Shimano does not produce SGS long cage versions for road touring where climbing and climbing with a load requires the larger cogs (at least for us non-pro's)


Yes, it is the GS. There is no SGS designation for it but the cage itself is physically longer than in past models. It will also handle the 34 with no upper pulley interference as I indicated above. It is 105 though. XT would be more along Ultegra lines.


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## frdfandc (Nov 27, 2007)

tednugent said:


> Does a 9-speed shimano MTB rear derailleur work with 9-speed road shifters?
> 
> My 10-speed 105 shifter is mated to a 9-speed XT rear derailleur


Yes it works.


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## cxwrench (Nov 9, 2004)

tednugent said:


> Does a 9-speed shimano MTB rear derailleur work with 9-speed road shifters?
> 
> My 10-speed 105 shifter is mated to a 9-speed XT rear derailleur


Yes, 8, 9, & 10 speed Shimano road shifter will work w/ any 8 or 9 speed Shimano rear derailleur. They will NOT work w/ any 10 speed (Dyna-sys) mountain rear derailleur. 

The 5701 GS (mid cage...there is no 'long' cage rear derailleur in Shimano's road parts) _might_ work w/ a 34. Apparently it has on some bikes, but there is no way to know for sure w/o trying. @ghettocop has had it work on certain bikes, but...

The only way to know _for sure, without a doubt_ that you won't have problems w/ a 34t large cog is to use a mtb derailleur.

Shimano says the GS cage road derailleurs will work w/ a 30t large cog when using a triple, and a 32t large cog when using a double.


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## Brownie0629 (Jul 5, 2014)

ghettocop said:


> Yes, it is the GS. There is no SGS designation for it but the cage itself is physically longer than in past models. It will also handle the 34 with no upper pulley interference as I indicated above. It is 105 though. XT would be more along Ultegra lines.


OK, but will the new 10-speed 105 RD-5700 GS work with my 9-speed 105 STI shifters? My shifters would be what was the current 105 STI model for 2006.


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## Brownie0629 (Jul 5, 2014)

ghettocop said:


> I understand this. The new 105 long cage will handle a34 tooth cog without resorting to crazy B screw manipulation. I have customers using this set up with success. It gives an alternative to WiFli or MTB stuff.


By "crazy B screw manipulation" I assume that you are referring to reversing the B screw? I tried that too, and it did help a little. Like I said, it works after a fashion but its not ideal. The shifting is not crisp. I can tell its just a little beyond the limit for the Ultegra. Has no problem with the 30T cog, its the 34T that seems to go over the line.

Interesting about the new 105 RD handling the 34T cog. Not knowledgeable about the design of derailleurs but it seems to me that its not just the length of the cage. The cage length is needed to handle the longer chain length but it also seems that there might be differences in the geometry and spring tension necessary for the larger cog?


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## tihsepa (Nov 27, 2008)

Brownie0629 said:


> By "crazy B screw manipulation" I assume that you are referring to reversing the B screw? I tried that too, and it did help a little. Like I said, it works after a fashion but its not ideal. The shifting is not crisp. I can tell its just a little beyond the limit for the Ultegra. Has no problem with the 30T cog, its the 34T that seems to go over the line.
> 
> Interesting about the new 105 RD handling the 34T cog. Not knowledgeable about the design of derailleurs but it seems to me that its not just the length of the cage. The cage length is needed to handle the longer chain length but it also seems that there might be differences in the geometry and spring tension necessary for the larger cog?


Correct, its the spacing between the pivot and the upper jockey wheel. Not the cage. 
The reason that is works on some bikes and not others is due to the hanger length. A longer hanger puts the derailuer lower on the frame as compared to the cassette. 
No need to ghetto rig the b screw if you use the correct parts.


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## junior1210 (May 2, 2013)

Microshift makes a road rear derailleur (RD-R51M) that will handle up to 34T cogs.


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## Roland44 (Mar 21, 2013)

frdfandc said:


> The XT RD will work just fine. Don't forget a new chain as well. Or if you want to save a couple of bucks, try to find an SLX 9 speed RD.


+1 for SLX 9 speed RD!


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## tihsepa (Nov 27, 2008)

junior1210 said:


> Microshift makes a road rear derailleur (RD-R51M) that will handle up to 34T cogs.


Yeah but its Microshift.


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## Brons2 (Apr 7, 2006)

ghettocop said:


> I understand this. The new 105 long cage will handle a34 tooth cog without resorting to crazy B screw manipulation. I have customers using this set up with success. It gives an alternative to WiFli or MTB stuff.


New meaning the 5800 GS? I'm using a Deore M-591 now to shift my 11-34 but would prefer the aesthetic of the 105.


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