Bicycle Mechanics - Shimano 8- and 9- speed derailleur compatibility

OK, I'll admit I posted this question on the mountain forum as it applies to my older M950 XTR rear derailleur, but no one is responding to it over there. Road forums get more traffic, and I know there are credible gearheads over here also. My question is simple: can I run the older M950 XTR rear derailleur with a nine-speed cassette and shifters? I know the indexing detents are in the shifters because I saw where my old eight-speed ones are (the shifters are broken and I'm ready to update to nine-speed).

Shimano's site has some FAQs that state eight-speed derailleurs might not want to shift onto larger cassette rings, like a 34 granny. So I could always get, say, an 11-32. Plus the derailleur is long cage, so hopefully I'm not in bad shape with reaching some gears.

The shops I've called are giving me wishy-washy answers on the compatibility question, and I KNOW someone here can shed some light on the topic.

BTW, the 950 rear der. looks identical to the 952/3 model, except it doesn't say "Mega 9" on the cage.

Yes, you can run that derailer with 9-speed cassette and shifters. Only Dura-ace has specific 8-speed and 9-speed derailers. All other Shimano derailers can be used for either.

You can probably get the M950 to run on a 34. I have an old Deore and I got it to run on a 34. Make sure the chain is long enough and you may have to adjust the "B" tension screw.

I'm no expert, but since no one has responded......

All I know is that the road stuff is NOT compatible.
All the old 6, 7, and 8 speed road stuff uses pretty much the same spacing, but when they went to 9 speed, they chose to narrow the chain and narrow the cog spacing.What?? 6,7,and 8 speed spacing were all different cog spacing no matter road or MTB. All road and mtb stuff except pre 9 speed DA shifters and RD are intercompatible(shifters and casettes have to be same speed,and road RD won't shift some of the bigger mtb cogs.)

Yes, you can run that derailer with 9-speed cassette and shifters. Only Dura-ace has specific 8-speed and 9-speed derailers. All other Shimano derailers can be used for either.


Actually, it was the pre 9 speed DA RDs that have the unique throw ratio. 9 speed DA RD have the same throw ratio as any other shimano sis RD with the noted exception.

OK, I'll admit I posted this question on the mountain forum as it applies to my older M950 XTR rear derailleur, but no one is responding to it over there. Road forums get more traffic, and I know there are credible gearheads over here also. My question is simple: can I run the older M950 XTR rear derailleur with a nine-speed cassette and shifters? I know the indexing detents are in the shifters because I saw where my old eight-speed ones are (the shifters are broken and I'm ready to update to nine-speed).

Shimano's site has some FAQs that state eight-speed derailleurs might not want to shift onto larger cassette rings, like a 34 granny. So I could always get, say, an 11-32. Plus the derailleur is long cage, so hopefully I'm not in bad shape with reaching some gears.

The shops I've called are giving me wishy-washy answers on the compatibility question, and I KNOW someone here can shed some light on the topic.

BTW, the 950 rear der. looks identical to the 952/3 model, except it doesn't say "Mega 9" on the cage. It works with a 9 speed casette and shifters.Pre mega range RD were speced for 32 tooth max cog. Spec is usually conservative. You got it,try it. FWIW, cage length has nothing to do with it.

Excellent work, thank you all for the input. Now I shouldn't have to shell out an extra hundred bucks for another derailleur I don't (yet) need.

Excellent work, thank you all for the input. Now I shouldn't have to shell out an extra hundred bucks for another derailleur I don't (yet) need.Well, you can certainly get by for much less than $100.

Just to let anyone searching for this old thread know, I just did the same upgrade myself from a 9 speed LX to an XTR 950, and it works great!!!

Thanks everyone for explaining this compatibility issue, Shimano really sucks at keeping an archive of these parts and I just bought a used m950 hoping it would work with 9-speed. Nice work!!! (my confidence is restored)

Thanks everyone for explaining this compatibility issue, Shimano really sucks at keeping an archive of these parts and I just bought a used m950 hoping it would work with 9-speed. Nice work!!! (my confidence is restored)
Sheldon Brown has some good compatibilty info on several of his pages. Start here: SB speeds page (http://www.sheldonbrown.com/speeds.html)