Shimano XT m772 help

[DWChan]

Hey All,

I'm working on a miyata 912 conversion and updating the drivetrain and run into an issue. I'm using a Shimano XT m772 and Dur-Ace 7700 downtube shifters. The derailleur doesn't have a barrel adjuster. What are my options to help with indexing? 

Also, can these shifters be used in friction mode? If so how do I engage that. Thanks a bunch.

--Donald--

[Nick Payne]

You could use an inline barrel adjuster on the section of Bowden cable
between the derailleur and the cable stop on the chainstay. Something
like this: http://www.wiggle.co.uk/bbb-bcb-95-in-line-gear-barrel-adjuster/

I used one of these adjusters on my Bleriot, with the same derailleur,
where I was using barend shifters and the downtube cable stops have no
provision for an adjustment mechanism.

To put the rear shifter into friction mode, look at the shifter where it
attaches to the downtube. Around the fixing screw there is an annular
housing with a small red triangle marked on it. With the shifter in
indexed mode, the triangle is opposite a mark on the shifter body
labelled SIS. Use the d-ring attached to the housing to turn it through
about 90 degrees, to the setting marked Friction.

Nick

[DWChan]

Thanks Nick,

I was looking at an inline adjuster but wanted something a little more elegant. I found this on a tip from a group member and I think it will do the trick. 

Also, There isn't a marking for friction, just SIS. But, if I rotate the D-ring counter clockwise, the indexing isn't as severe and eventually disappears but is very loose. Does this mean that friction mode is engaged? 

Thanks,

Donald

[Nick Payne]

Looking at the picture of the IRD adjuster, it doesn't look to me as though it would fit on the M772 I have, as there is insufficient space next to where the cable enters the derailleur body to accommodate the plastic adjusting barrel on the IRD adjuster. My M772 SGS looks like this: http://www.triuk.com/media/product-images/shimano-deore-xt/rdm772gs.jpg.

As for the DT shifters, on both of the 7700 DT shifters I have there are clearly marked settings for SIS and friction, as in the attached image, and switching between the two works as expected.

On 02/09/14 08:45, DWChan wrote:

[Jim Bronson]

Those sort of derailers with straight-through cable routing and no barrel adjuster were meant for mountain bikes, to improve clearance.  I have one on my Soma GR (Deore M-592) and it works OK, but I run bar-ends and my downtube cable stops have barrel adjusters on them.  So I use those to adjust the shifting and it works tolerably well, but honestly I think I would prefer a different derailer, just not enough to go buy one (yet).

I don't think Shimano ever imagined this style of rear derailer being used with downtube shifters.  There are some inelegant solutions as some have mentioned but I think the best solution is to just use a normal style derailer instead.

$0.02

-Jim

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Keep the metal side up and the rubber side down!

[blakcloud]

I have that derailleur on two bikes and in hindsight, and also agreeing with Jim, it may not be the best derailleur if you don't want to use inline barrel adjusters. The first time I used that derailleur with bar end shifters, I just got very lucky and it worked by getting the right tension on the cable. I then switched out to Paul Thumbies and everything was fine. Second the way the cable enters the derailleur and you have to cut it extremely short as not to hit the spokes is a pain.

Also looking at the IRD, doesn't it have to thread into the derailleur which the XT won't do? I could be wrong but check it out first.

[William Lindsay]

I stocked up on the M750-series rear derailers when I saw the M772, so I could retain the built in barrel adjuster

[Kieran Joyes]

I could never get by without a barrel adjuster on the RD. I can't even fathom not having one!

KJ

[DWChan]

I didn't notice the lack of a barrel adjuster and would have gone with a different one had I known... The good news is that I think I found a solution with jagwire mickey adjusters. They are a ferrule style and thin enough to run on the derailleur or perhaps even at the cable stop on the chainstay. I'll report back when I get it.

[Andrew]

Option A: Jagwire / Ritchey "rocket"

https://www.flickr.com/photos/ah_blake/8327567709/

Option B: Jagwire Mickey

https://www.flickr.com/photos/ah_blake/14706553316

Option C: Alivio Shadow

http://enduromag.com.au/site/wp-content/uploads/2014/03/RD-M4000-SGS_STD_01.jpg

Or get an M591 mech.

[DWChan]

The jagwire mickey didn't fit like option B. Went with an inline. 

Here is a pic of the build so far

[William Lindsay]

That is dynamite.  Miyata 912 makes a really great conversion.  Nice wide stance fork crown and fender eyelets are two of the many highlights of those bikes.  Great work.  

Bill Lindsay

El Cerrito, CA

[DWChan]

Thanks Bill! Is this flickr set on your conversion you? If so, you still have your 912?