SRAM NX Rear Derailleur - swinging on the hanger

[Odinson]

Okay, guys. Another Q&A.

 

I'm doing my own wrenching for the first time, so apologies in advance if my question seems daft.

 

When affixing my new SRAM NX RD to the hanger of my bike and with the nut/screw/whatever fastened, the RD can still move freely (swing) on the RD. By "swinging", I mean that with the RD fastened to the hanger and looking at the bike from the right side, it can move/swing to the left. It obviously stops on the hangar stop, but can still move towards the back of the bike.

 

Now, is it supposed to be able to move freely to the back of the bike or should it be completely fixed to the hanger?

[Meezo]

no its normal...

 

don't stress!

[Captain Fastbastard Mayhem]

That's fine. Supposed to be like that, the chain tension keeps it in place. 

[shaper]

I assume you have not put the chain on yet?... then it wont move as freely

[Wannabe]

There is however a little "stopper plate" (for the lack of a better word) that must be in the correct position against your derailer hanger.

 

[Odinson]

Nope, the chain isn't on yet.

 

Figured that might be a factor, but thought it was a bit odd. I guess the chain tension and the gear cable outer should keep it from swinging about.

 

If all goes well, I should have some pics up soon of my new bling.

[JXV]

Yes it must be able to swing freely backwards around the attachment bolt but it should not have any lateral freeplay, especially if it is a new RD. When a chain is threaded through the RD cage and joined it will pull the cage forward against the RD spring tension and this is what will hold the RD forward against the hanger stop. The hanger stop in combination with adjustable 'b' screw sets the clearance of the top pulley in the cage to the largest gear in the cassette. Some rearward movement off the hanger stop (against RD spring tension) is needed to accomodate gear changes and the odd twig that will inevitably get caught up between the chain and cassette.

 

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[Odinson]

Yes it must be able to swing freely backwards around the attachment bolt but it should not have any lateral freeplay, especially if it is a new RD. When a chain is threaded through the RD cage and joined it will pull the cage forward against the RD spring tension and this is what will hold the RD forward against the hanger stop. The hanger stop in combination with adjustable 'b' screw sets the clearance of the top pulley in the cage to the largest gear in the cassette. Some rearward movement off the hanger stop (against RD spring tension) is needed to accomodate gear changes and the odd twig that will inevitably get caught up between the chain and cassette.

 

Sent from my SM-G900F using Tapatalk

 

Great explanation, JXV!

 

Doing your own wrenching can often times be equal parts frustration and sense of achievement.