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Hi folks,

I searched the archives on this, and everyone has a little chain rub, but not like this.

I'm using the previous XTR front Der, top swing, an M752 I believe. On the small ring/large cog the inner plate rubs the chain. On the Large Ring/small cog, outer plate rubs. Now, here's the baffling part. I have both limit screws dialed all the way out...moving those cages away. Am I missing something?

Now, of course I'm using an slightly unusual crank with brand new 9sp FSA rings. I suppose it's possible that the large and small rings are a bit farther outboard/inboard than an XTR crank. But, I don't imgine the BB spindle is the issue, since moving the cranks in or outboard would make either problem worse. UGH!

Thanks,
Ginz
 

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More problems with XTR

I really can't help you with that because my FD-M952 derailleur shifts very well without any rubbing in my Epic. XTR has differential plates that move independent of each other so you SHOULD be able to set it so that it doesn't rub.

Anyway - I have an another problem: while the front der. shifts very nice, it drops the chain from middle to small chainring in front when you are really hammering the pedals. When pedaling normally, there are no problems. What could make this chain drop to happen ???
It seems that the FD is about 1-2mm too low but I don't know if raising the derailleur would solve the problem...

BTW: this problem did not occur with FD-M760 XT front der.

Thanks for any help!
 

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Ginz said:
Hi folks,

I searched the archives on this, and everyone has a little chain rub, but not like this.

I'm using the previous XTR front Der, top swing, an M752 I believe. On the small ring/large cog the inner plate rubs the chain. On the Large Ring/small cog, outer plate rubs. Now, here's the baffling part. I have both limit screws dialed all the way out...moving those cages away. Am I missing something?

Now, of course I'm using an slightly unusual crank with brand new 9sp FSA rings. I suppose it's possible that the large and small rings are a bit farther outboard/inboard than an XTR crank. But, I don't imgine the BB spindle is the issue, since moving the cranks in or outboard would make either problem worse. UGH!

Thanks,
Ginz
My understanding is that older style XTR f der only work on standard 110mm chainrings. Won't work on compact crank sets.
 

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Mantis, Paramount, Campy
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Not True

This is mostly marketing hype. Besides XTR hasn't used 110mm rings since 1994-1995.

Even the original M900 XTR front (which was probably Shimano's best MTB derailleur) works fine with 44T, 42T or smaller outer rings. Samr can be said of "compact" front derailleurs. A current XT, LX or whatever doesnt really have any problem handling a 48-36-36 crankset from back in the day.

To comment on the original question I had a similar problem with my outer ring and found that the arms of the ring that mounted to the crank were thicker than the stock rings I replaced. I had to shave them down to get proper shifting.
 
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