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B screw on rear derailler question

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B screw on rear derailler question

Old 09-21-08, 07:34 PM
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B screw on rear derailler question

I've got a Deore Dx rear der on my Miyata 1000 (1991). I just changed out the rear cassette to a 7 spd 34t (it was a 7 spd 28t). The rear der will reach the 34t cog with no problem, but there is a bit of rub between the bottom cog on the cassette and the top pulley wheel of the rear der. I screwed the B screw in all the way but there is still a small amount of rub. Do I need a new rear der? Any other ways to solve the problem? I've never had this happen before. I've got another bike w/ an 8 spd 34t cassette and it works fine w/ my new Deore rear der. Would the Deore DX rear der (which was original to the Miyata 1000) be proportioned a bit differently than the 2008 Deore der?

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Old 09-21-08, 08:08 PM
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There are different lengths of RDER's. GS & SGS
Maybe a longer B screw?
Chances are you'll need a different RDER though.
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Old 09-21-08, 08:21 PM
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Here's a little trick that I've done myself, hopefully you'll have the same success.

Take the screw completely out. Screw it in the other way. Know what I mean?
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Old 09-22-08, 05:12 AM
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GS vs SGS:


I have a Deore LX "GS" rear der on my mtb but my rear cog goes up to 28T... the GS rear supposely supports a cassette with the biggest cog being 30T... I haven't tried to exceed it but interestingly enough, Shimano calls both the GS and SGS rear ders "long cage", as Sheldon's website mentions.

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