I filmed a little video of the process: https://youtu.be/ejJsIWrrFTU

Does anyone know how to solve the problem? Apart from attaching piece of rubber to the chainstay? It is really annoying, because if terrain becomes even a little bit rough, like messed pavement with pot holes and cracks, there is always that rattling sound. I heard that SRAM RD's are better and do not hit the chainstay. I'd like to stick to 9 speed if possible. I am currently running 1x9 setup. As you can see 9 speed cassete alivio or acera (not sure on this), Deore - RD, and Acera shifter. I want to upgrade to 1x11 eventually, but for the time being I just don't have much money to spare. I was thinking about buying SRAM 9 speed for ~60$, will it help? Will it work with my shifter? Are there any other solutions?


2 Answers 2


Rear derailleur adjustment can be a really pain in the neck. What is more likely happening is that you have to adjust the B screw:

B-Screw Adjustment After setting the L-screw, check the "B-screw" for an adequate setting. The B-screw controls the derailleur body angle, hence the name, B-screw.

You can find detailed information about all the setting for a rear derailleur here, including the screw (B-screw) that adjusts distance to the bike frame. You should adjust this AFTER the other two screws that adjust upper and lower limits relating to the cassette are properly adjusted, so follow ALL the steps one by one and you should be good.

It is also possible your derailleur hanger needs alignment. Watch your bike from behind and see if the body of the derailleur goes down parallel to the bike frame. If it doesn't, you need to adjust with a specific tool, so you should take your bike to a shop because it's not worth buying it. You can find more information about hanger adjustment here.

Good luck!


The screw adjustment you point the camera to @20s needs to be turned in. This will rotate the derailleur away from the chain stay. The screw pushes against a protrusion on the derailleur body.

  • I tried that yesterday. Screwed it all the way in. It messed up shifting. Do I have to screw that in and readjust? I also removed 3 links from my chain. this is how it looks like on biggest and smallest cogs: imgur.com/sXX7Hbp,ZLTQ8tE#0
    – YKY
    May 18, 2015 at 20:52
  • Chain looks OK now, but if you get the dérailleur rotated to clear the chain stay it may be too short. You should adjust the screw (and the high and low stops) then adjust the the shifting. The screw is used to set the clearance between the dérailleur and cluster, which should be about 5mm (Closer gives more precise shifting, too close rubs). Best bet is use google to find out how, and treat as if its an install of a new dérailleur (This adjustment should not be needed after initial installation)
    – mattnz
    May 18, 2015 at 22:10
  • It should be quite simple to adjust, so if you have problems with this adjustment, consider It is also possible other things like dérailleur alignment or dérailleur is faulty
    – mattnz
    May 18, 2015 at 22:16
  • I will try to do that tomorrow. However, when I screwed it all the way in the last time, it would still hit chainstay on samller cogs. Are all derailleurs like that? Or it is a design flaw? It is not aftermarket part or something. Came with the bike.
    – YKY
    May 18, 2015 at 23:07

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