Will 11-36T MTB cassette and rd m773(XT) or M980(XTR) work with my 7800 STI road levers



Eichers

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Hi All, as the title suggests, will 11-36T MTB cassette and rd m773(XT) or M980(XTR) work with my 7800 STI road levers.

cloudhead has used an 11-32T XT MTB cassette and RD M773(XT) with 5700 STI road levers without any issue.

So, I wondering if others have done anything like this without any issues :)

Thanks
 

alfeng

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Jul 23, 2005
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FWIW. I don't see why the 11-36t cassette & XT/XTR derailleur + DA shifter combination wouldn't work ...

BUT, you may want to simply opt for a 38t 130BCD chainring, first because it will be cheaper & much easier ... by my reckoning, the 38t chainring with a 34t cog will be about halfway between a 39t chainring & 34t cog & a 39t chainring & 36t cog ...

Changing to a 38t chainring may be the extra difference you are looking for on the low end.
 

Eichers

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Originally Posted by alfeng .

FWIW. I don't see why the 11-36t cassette & XT/XTR derailleur + DA shifter combination wouldn't work ...

BUT, you may want to simply opt for a 38t 130BCD chainring, first because it will be cheaper & much easier ... by my reckoning, the 38t chainring with a 34t cog will be about halfway between a 39t chainring & 34t cog & a 39t chainring & 36t cog ...

Changing to a 38t chainring may be the extra difference you are looking for on the low end.

Thanks alfeng, can you clarify "don't see why the 11-36t cassette & XT/XTR derailleur + DA shifter combination wouldn't work"

I have an 11-34T XT 10spd cassette that I can try this with. Excluding cost, which do you think would work best, an XT 10spd RD or XTR 10spd RD, with the 7800 STI road shifter?

I didn't know you could get a 38T/130BCD chainring, but I will definitely look at that when the 39T wears out ... thanks :)
 

alfeng

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Jul 23, 2005
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Originally Posted by KLabs .


... can you clarify "don't see why the 11-36t cassette & XT/XTR derailleur + DA shifter combination wouldn't work"

I have an 11-34T XT 10spd cassette that I can try this with. Excluding cost, which do you think would work best, an XT 10spd RD or XTR 10spd RD, with the 7800 STI road shifter?
If the cog spacing is the same for the 10-speed Shimano/-compatible ROAD & 10-speed MTB cassettes, then[COLOR= #0000ff] I believe that the reason [/COLOR]-- and, probably the only reason -- [COLOR= #0000ff]that Shimano says that the 10-speed MTB rear derailleur is not compatible is because it uses the RAPID RISE (reverse pull) design ... [/COLOR][COLOR= #000000]on the road, that means that the small shift paddle would be used for down shifting to larger cogs and the brake lever's assembly would be used for up shifting to smaller cogs ... would THAT be a real world problem? I don't think so.[/COLOR]

  • As I said 2-or-3 years ago, I thought the most recent iteration of the Shimano's Road shifters & derailleurs would switch to the Rapid Rise design and thereby eliminate the downshifting "dwell" which was designed into the original Shimano Road shifters ...
  • I was wrong ...
  • But I think the reason I was wrong was due to the belated release of the Di2 & the necessity to have the DA 7900 rear derailleur more-or-less look the same as the Di2 rear derailleur, and vice-versa ([COLOR= #808080]that's my story, and I'm sticking to it ... after all, look at the comparatively retro-look of the Di2 shifters[/COLOR])

While 'I' don't think that the geometry of the 9-and-10-speed rear derailleurs is the same, others say they are ...

  • as I have demonstrated to MY satisfaction, a hubbub'd 9-speed Shimano rear derailleur & a 10-speed Shimano rear derailleur result in the SAME INDEXING, so the out-of-the-box geometry cannot be the same ... at least, IMO ... or, as they might have said a generation-or-two ago, QED.

However, if those people are correct and/or you believe them, then I would choose the last iteration of the 9-speed XTR Shadow rear derailleur because it looks better to me ... worst case scenario, you could hubbub the connection to achieve 10-speed indexing UNLESS Shimano has gone-off-the-reservation with regard to mult-generational component continuity ...

XT & XTR rear derailleurs have always been interchangeable in the past, so I don't know why they wouldn't be in the 10-speed generation of components.

Consequently, FWIW, if I were opting for a 10-speed Shimano MTB rear derailleur, I would just choose XT components because the picture of the 10-speed XTR which I saw was unattractive ([COLOR= #808080]to me[/COLOR]) ...


  • that is, when in doubt, choose XT because it is much less expensive than XTR ([COLOR= #808080]more so, now, than a dozen years ago ... or, so it seems to me[/COLOR]) & slightly more robust (not an issue for most-if-not-all Road applications) ... that is, I don't think the XTR's carbon fiber pulley cage warrants the price difference ([COLOR= #808080]I presume the 10-speed XTR rear derailleur has a carbon fiber pulley cage[/COLOR])
  • While there is a weight difference between the XT & XTR rear derailleurs, the difference seems to be less with each iteration, so the choice is probably mostly cosmetic -- NOTHING WRONG WITH THAT.

Of course, just to sound like a broken record, you could always switch to 10-or-11-speed [COLOR= #ff0000]Campagnolo shifters[/COLOR] ...

  • you can get a set of 11-speed Campagnolo Athena shifters with carbon fiber levers on eBay for about $200US, Chorus shifters are $50-or-so more ... even more for Record & Super Record shifters.

BTW. 10-speed Campagnolo shifters + a 10 speed SRAM Road rear derailleur == 10-speed Shimano indexing

  • I don't know ([COLOR= #808080]i.e., I have already forgotten!?![/COLOR]) what the compatibility is with the SRAM Apex (?) rear derailleur & other SRAM Road derailleurs, but if it is compatible, then you can plug it into the equation with 10-speed Campagnolo shifters.
 

Eichers

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Hi Alfeng, thanks but I am sorry, I really didn't understand your answer, completely. Are you saying that it will work? :)
 

alfeng

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Jul 23, 2005
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Originally Posted by KLabs .

Are you saying that it will work? :)
Darn!

Okay, I'm confused ... or, I was ...

But, your query ([COLOR= #808080]in a different thread[/COLOR]) about what does indeed appear to be a Shimano XT-772 rear derailleur on cloudhead's bike made me belatedly take a look at pictures of the 10-speed Shimano XT-773 & XTR-980 rear derailleurs ...


Holy Cow!

THOSE pictures were-and-ARE a revelation ([COLOR= #808080]to me, anyway[/COLOR])...

But, looking at pictures of the XT-773 & XTR-980 rear derailleurs reveals that it would be mechanically simpler if they were "regular" rise ... ([COLOR= #808080]I later checked to see how Harris Cyclery classified the SLX 662 rear derailleur, and it is indeed NOT Rapid Rise!?![/COLOR]) ...


  • By my reckoning, the [COLOR= #0000ff]longer boom[/COLOR] ([COLOR= #808080]for want of a better description[/COLOR]) on the XT-773 moves the fulcrum about 10mm further aft and effectively changes the geometry in a manner similar to the forward placement of the anchor point on a traditional 10-speed Shimano Road rear derailleur vs. the anchor point on a traditional 9-speed Shimano Road rear derailleur -- that is, the longer, subsequent hypotenuse of the 10-speed Shimano MTB rear derailleur traced by the derailleur cable echoes hubbubing a 9-speed Shimano rear derailleur cable to effectively make the latter a 10-speed rear derailleur.

Because I mistakenly believed AND mis-stated more than one time that the Shadow rear derailleurs were Rapid Rise, it is not surprising that my mis-statement has unintentionally & undoubtedly resulted in part-if-not-all of your confusion ...

Mea culpa ...

Because the XT-773 & XTR-980 are "normal" rise, I don't have a clue why Shimano says that they can't be used with their Road shifters unless THAT is simply an echo of a 12+ years ago when the marketing people said that you could only use 105 with 105, Ultegra with Ultegra, and Dura Ace with Dura Ace (and, THAT was partially a legacy from when the earliest DA shifters apparenty were indeed not compatible with the 105 & 600 series derailleurs).

Ideally, the 10-speed Shimano MTB rear derailleurs act the same a hubbub'd 9-speed Shimano MTB rear derailleur; but, you never know ...

If so, it should work.

  • Regardless, while I continue to contend that you-and-everyone-else have to abandon what I believe is the persistent misperception that any 10-speed Shimano rear derailleur is directly interchangeable with its earlier bretheren, [COLOR= #ff0000]I recommend that you "borrow" the molly-hook anchor washer from a regular Shimano rear derailleur and attempt to hubbub the rear derailleur connection to see if doing so improves the accuracy of the indexing & thereby makes the shifting less "clunky" before ponying up for a XT-773 or XTR-980 rear derailleur[/COLOR] because someone in Osaka may have gone rogue when the 10-speed MTB rear derailleurs was spec'd AND they may have actually designed them to NOT be backward compatible as the past couple of generations of indexed Shimano rear derailleurs have been.

But, the proof is in the pudding, so you will have to be the pioneer as far as the compatibility ... OR, that was a really long way of saying "I don't know" definitively one-way-or-the-other.
 

Eichers

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Quote: Originally Posted by cloudhead .

Hi, spoke to my mechanic who set it all up, and you're correct, it's a 9-speed Deore XT shadow with a 10sp Dynasys cartridge. He said the reason for this is that the 10sp Dynasys derailleurs aren't compatible with the STI shifters.


Hi cloudhead, thanks for the confirmation that you are using a 9spd M772 XT RD and XT 10 spd cassette :)
This is still good news in that it means that an XT or XTR 9spd RD and an STI road lever will work with with a Shimano or SRAM 10spd cassette :)


This still raises a question about the M773 RD's compatibility, because it is nolonger compatible with the current STI road levers.
If the M773 is not compatiable with Shimano STI road levers, could it now be compatible with SRAMs road levers (ie. 1:1 actuation) :)
 

alfeng

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Jul 23, 2005
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Originally Posted by KLabs .



Hi cloudhead, thanks for the confirmation that you are using a 9spd M772 XT RD and XT 10 spd cassette :)
This is still good news in that it means that an XT or XTR 9spd RD and an STI road lever will work with with a Shimano or SRAM 10spd cassette :)


This still raises a question about the M773 RD's compatibility, because it is nolonger compatible with the current STI road levers.
If the M773 is not compatiable with Shimano STI road levers, could it now be compatible with SRAMs road levers (ie. 1:1 actuation) :)

Well, if you can wait a couple of years, I'll probably be curious enough by then to pony up for a 10-speed Shimano MTB rear derailleur ...

But, before then, I've got too many other projects which have meaning for me.

If you are looking for better shifting, I can't say it often enough, if smooth downshifting is a desired result and you don't want to buy a Di2 drivetrain then Campagnolo shifters will make you wonder why people use Shimano or SRAM shifters.

In the meantime, as I previously suggested, you should try hubbubing your rear derailleur cable's anchoring ... at least, try it before you spend the money for another cassette.
 

Eichers

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Hi alfeng, thanks for the info (Campagnolo, hubbubing, etc). What actuation ratio are Campagnolo shifters ...
 

alfeng

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Jul 23, 2005
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Originally Posted by KLabs .

What actuation ratio are Campagnolo shifters ...
As I have mentioned before, and contrary to what others have declared, a hubbub'd 9-speed Shimano rear derailleur (ROAD or MTB) is equivalent to a 10-speed Shimano rear ROAD derailleur ...


To achieve 10-speed Shimano indexing, you can either use an 11-speed Campagnolo shifter with a 9-speed Shimano rear derailleur OR ([COLOR= #808080]by my extrapolation[/COLOR]) a 10-speed Campagnolo shifter with a hubbub'd 10-speed Shimano ROAD rear derailleur.