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Discussion Starter · #1 ·
Does anybody know how to tell if I have an SG - Long cage or and SGS "super long cage" rear derailleur in M980?

http://techdocs.shimano.com/media/t...RD/EV-RD-M980-3085A_v1_m56577569830799959.pdf

http://techdocs.shimano.com/media/t...SI-5XC0A-001-00-ENG_v1_m56577569830702244.PDF

Shimano says the SGS can go up to 41 teeth but the SG can only do 35. I've been running an 11-36 cassette problem free so I assume it's an SGS but I can't seem to get the One Up 42 tooth ring to work. (I was hoping for 1 tooth leeway)

My Derrailleur hangs up on the 42 tooth when I shift there and I can't get out. I had to dial in the tensioner screw all the way to keep the pulley from dragging on the chainring.

Originally with my old chain I tried taking out links but that made the pulley to chainring drag way worse. Anybody have any ideas? Damn shimano needs to pull their head out of their own arse and just make 1xsomething...
 

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My SLX long measures 100mm, SG 80mm.
The 41 and 35 is chain takeup capacity. They are both rated for a 36T rear cog.
You need a longer B-screw.
 

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Discussion Starter · #4 ·
My SLX long measures 100mm, SG 80mm.
The 41 and 35 is chain takeup capacity. They are both rated for a 36T rear cog.
You need a longer B-screw.
Thanks to both of you. Can you buy a longer one from Shimano, or I guess just hit a nut/bolt supply place with that one to get the same guage and pitch?
 

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The longer bolt is not an official fix, so Shimano doesn't provide one. Ask a local mechanic if they have a longer one. I know myself and several others keep spares from blown up parts that come in.
 

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Discussion Starter · #6 ·
My SLX long measures 100mm, SG 80mm.
The 41 and 35 is chain takeup capacity. They are both rated for a 36T rear cog.
You need a longer B-screw.
How are you measuring that? My XTR is 90 mm from centre to centre of the pulleys.
 

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Discussion Starter · #8 ·
Thanks chief.

I took the screw out and found that I simply could not thread it in backwards. The tapered threads just would not engage past 3 threads and I had no confidence in that.

When I took it appart I noticed the XTR derailleur incoorporates a washer between the head of the bolt and the body of the derailleur itself. I removed that oval shaped washer and found that gave me enough length to adequately tension the chain so the top pulley clears the teeth of the 42 tooth ring.

So far shifting is now flawless but I have no room for chain stretch at all. So I will be trying you suggestion eventually.
 
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