Rick@OCRR

Hi Mechanically adept folks,

I have a road bike that I'm gearing super low, i.e. fitted with an XTR 11-34 10 speed cassette. For shifters I have Ultegra 10 Speed STI.

I tried a new XTR 10-Speed derailluer . . . that didn't work. Apparently the "Shadow" spec isn't going to work at all.

I phoned Shimano in Irvine, CA and their tech-rep advised using the M-972, but the spec on that looks to be "Shadow" too. I think (could be wrong!) what I need is:

1. Non-Shadow
2. 9 - Speed mountain Shimano
3. Long Cage

Please advise if you've attempted/accomplished this (or something similar) what worked for you, Shimano rear derailluer wise?

Oh, the problem with the XTR Shadow I tried was that it didn't have enough horizontal range, i.e. I could have the 8 lowest, 8 highest or 8 middle gears, but not all 10.

Thanks in advance for your knowledge, advice and help.

Rick / OCRR

jimc101

You can't mix Shimano MTB 10 speed RD's (Dyna-sys) and Shimano 10 speed road RD's.

This is a common question on the froum, and the standard answer is to use a 9 speed Shimano MTB RD, if using a 10 speed cassette with 34T or more

Al1943

The 10-speed Shimano mountain rear derailleurs have an actuation ratio that is compatible with Shimano 10-speed mountain shifters only. Shimano 9-speed mountain rear derailleurs are compatible with Shimano 10-speed road shifters.

Shimagnolo

I can confirm the Shimano "9s" Shadow RD's work fine with Ultegra 10s STI.
I have two bikes set up this way with 11-36 10s cassettes.
With an 11-34 cassette, you wouldn't even need the "Shadow" type.

joejack951

I thought the "shadow" type was merely a lower profile RD. I think the more important thing to make sure of when buying a 9 speed MTB RD is that you get a "top normal" actuation derailler, as opposed to "bottom normal." The latter will reverse your shifter's up and down shift levers but will otherwise work. The XTR-M972 will work though it's quite expensive. Personally, I'd go with the standard XTR-M971. I picked one up a few years ago for $100 but I got lucky then. Here's one for $133 from the UK: https://www.chainreactioncycles.com/M...?ModelID=15186

Shimagnolo

The "Shadow" design does not pivot on the mounting bolt like other RD's.
It moves the pivot point 25mm to the rear of the mounting bolt.
The Shadow design was introduced before the 36T cassettes and was designed to accomodate them.

Rick@OCRR

Thanks everyone, for the information on compatible derailluers and also on the meaning of Shadow. I know about low-normal rear derailluers, in concept, but what are the Shimano codes for them . . . just so I don't buy one on ebay by mistake?

Thanks again!

Rick / OCRR

joejack951

It seems Shimano's pattern is:

Ending in "0" = rapid rise
Ending in "1" = traditional
Ending in "2" = Shadow

This applies for XT and XTR 9 speed only.

Rick@OCRR

Thanks joejack951,

Very helpful!

Rick / OCRR

skilsaw

Shimano makes a 10 sp Ultegra long cage RD that will work with your Ultegra 10 sp STI shifters.
This combination came stock on the Cannondale t1.

Rick@OCRR

Thanks skilsaw, That sounds like the best solution, but will it handle a 34t cog? My understanding is that it's limited to 28t. But I could be wrong!

Rick / OCRR

Al1943

You are correct, the Ultegra long cage will not work with a 34 or 36 cog and is questionable with a 30 or 32.

Rick@OCRR

Thanks Al1943,

So which rear derailluer would you recommend for this application?

My inclination at this point is to try to find one of the XTR rear derailluers that is old enough to be non-shadow, with a Shimano alpha-numeric code that ends in "1" and is 9-speed (i.e. sold as 9 speed) which will (by virtue of being XTR) have a long enough cage for the 34t lowest gear cog.

Is that right?

Rick / OCRR

himespau 

I went with a microshift long cage rear derailleur as it has a lot of people saying it had shifting similar to ultegra and weighed about the same (and was $35 shipped). I figured for 35 bucks, I could take a chance that it wouldn't be quite as good as promised.

Someone, I think over a Rivendell, had a good description on them and I went with the middle range model because, while the top of the line was more attractive to me, it didn't have the barrel adjuster that the middle range one did.

Jed19

Somebody on this Forums once reported on their Ultegra Long Cage RD working with the 34 cog and Ultegra 10-Speed shifters.

I have been thinking about the same set-up, and I think the consensus was something like "it really depends on your RD hanger" as to whether the 34cog can be shifted into.

If I recall correctly, it was a poster called 10Wheels who made his set-up work with the 34 cog.

Search 10Wheels posts to ascertain his set-up.

joejack951

Click the Chain Reaction Cycles link I posted above. That's the cheapest you'll find the XTR-M971 RD unless you use Ebay. It will work just fine with a 34 tooth cog. The only nitpick you might have with it is the lack of a barrel adjuster at the derailler. Just add an inline one on your rear derailler housing and you'll be fine.

And my one nitpick of your post is the comment regarding the cage length being enough for a 34T cog. Cage length only determines the amount of chain wrap capacity that the derailler has. Deraillers designed for triple cranksets and wide range cassettes need to be able to wrap more chain than those for doubles with close-ratio cassettes hence the multiple cage lengths offered by Shimano. Deraillers designed for extra large cogs have other geometry changes to allow them to clear these big cogs. The confusion comes from the fact that the same deraillers designed for clearing big cogs are usually also designed for lots of chain wrap.

Shimano has three cage lengths and two derailler types, SS and GS for road and GS and SGS for MTB. In general, the following applies:

SS road: double crankset, road cassette (max cog 27/28T)
GS road: triple crankset, road cassette (max cog 27/28T)
GS MTB: double crankset, MTB cassette (max cog 34T)
SGS MTB: triple crankset, MTB cassette (max cog 34T)

Road and MTB triple cranksets have generally the same tooth difference from big to small (20-22T) so you could use either option interchangeably in the list above. for example if someone wanted a MTB with a close ratio road cassette, they could use a road GS rear derailler.