Reinstalling RED rear derailler, am I missing a spacer?
04-28-13, 09:27 PM
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Reinstalling RED rear derailler, am I missing a spacer?
Help! I am really puzzled I have removed my Sram RED rear derailleur to straighten the hanger and now trying to reinstall the rear derailleur. 
I have refitted it which it seems to be correct and have tightened the B-Bolt but the derailleur still has a lot of movement. I have repeated this a couple of times but it still doesn't seem right. Am I missing a spacer between the bottom bracket and b-bolt on the derailleur?
I have stopped tightening to avoid stripping the thread on the hanger and bolt.
I have looked all around the bike and workstand area and cannot see a spacer, I don't think anything has fallen off. (I haven't been able to find any diagrams,videos, or info online indicating if there is anything between the two mounting surfaces)
Any advice would be appreciated, I have attached a pic.
I have refitted it which it seems to be correct and have tightened the B-Bolt but the derailleur still has a lot of movement. I have repeated this a couple of times but it still doesn't seem right. Am I missing a spacer between the bottom bracket and b-bolt on the derailleur?
I have stopped tightening to avoid stripping the thread on the hanger and bolt.
I have looked all around the bike and workstand area and cannot see a spacer, I don't think anything has fallen off. (I haven't been able to find any diagrams,videos, or info online indicating if there is anything between the two mounting surfaces)
Any advice would be appreciated, I have attached a pic.
04-29-13, 01:17 AM
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When you say "movement" do you mean side-to-side or back and fourth?
04-29-13, 01:48 AM
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It would help to see a picture or two of the derailleur mounted on the frame showing us where you are having a problem.
That aside, when you are installing the derailleur, are you rotating it so the b-screw is clearing the tab on the back of the derailleur hanger? Or is it mashing against the side of the hanger? The end of the b-screw should rest against the flat tab on the hanger.
-j
That aside, when you are installing the derailleur, are you rotating it so the b-screw is clearing the tab on the back of the derailleur hanger? Or is it mashing against the side of the hanger? The end of the b-screw should rest against the flat tab on the hanger.
-j
04-29-13, 05:12 AM
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^What he said, except the B-screw on this RD doesn't butt against the hanger's tab, but on an intermediate bit on the pivot that has a tab to engage the hanger instead of the screw.
04-29-13, 06:58 AM
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Correct. That "intermediate bit" rotates on the RD mtg bolt. It needs to be rotated CW enough for its tab to be behind the tab on the hanger as the RD is being installed, then rotated into contact with the hanger tab as the DR mtg bolt is tightened.
04-29-13, 07:21 AM
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Two points. The "B" screw is probably the most misunderstood adj on a bike. On my Sram 7 the "B" screw is to be adj so that the jockey wheel misses the largest sprocket on the cassette by 6mm.
Then even tho the dropout on my bike is straight and normal, to make the high and low stop screws more or less in mid range, I had to put a spacer on the RD mount bolt. It still let the RD thread full screw all the way thru the dropout. Others have said they have had to do this too.
Then even tho the dropout on my bike is straight and normal, to make the high and low stop screws more or less in mid range, I had to put a spacer on the RD mount bolt. It still let the RD thread full screw all the way thru the dropout. Others have said they have had to do this too.
