Unable to adjust rear derailleur

[jorgemartin]

Hello,

I've just installed a new rear derailleur and can't make it work.
It's a SRAM x9 short cage derailleur (working together with an SRAM dualdrive 3xspeed hub)

This is what I've done:
- Set the gripshift to position 9
- Rest the derailleur on the smaller sprocket
- Clamp the cable
- Twist the shifter while pedaling

When it gets to the big sprocket it doesn't want to come back.

One added complication is that I'm doing this with a nearly 4 metre long chain for a recumbent that must go through some tubing and a tensioner pulley. That's why I'm not so sure if the chain length is correct and I'm wondering it this problem is being caused by chain that is too short? Or is this completely unrelated?

Any ideas?

 

[Andy_R]

have you checked the gear cable...is it moving freely? When the chain is on the largest sprocket is the top jockey wheel clear of the sprocket or is it touching? What sort of angle is the cage at when you're on the largest sprocket? All these could give us more info and point to a solution. A photo would be useful

 

[jorgemartin]

Some pics:
http://farm7.static.flickr.com/6084/6100064731_136cc43e10_b.jpg
http://farm7.static.flickr.com/6183/6100065337_45e61472a7_b.jpg

have you checked the gear cable...is it moving freely? When the chain is on the largest sprocket is the top jockey wheel clear of the sprocket or is it touching? What sort of angle is the cage at when you're on the largest sprocket? All these could give us more info and point to a solution. A photo would be useful

 

[Angelfishsolo]

As Andy suggested first thing to check is that the gear cable moves freely. Any kinks or burs in the cable or sheathing will prevent the chain from moving largest to smallest cog.

 

[jorgemartin]

Have checked that the gear cable moves freely and have replaced outer which was a bit tatty. I'm of the mind that the guide pulley might be too close to the largest sprocket so I'm going to play with that...

 

[Angelfishsolo]

Have checked that the gear cable moves freely and have replaced outer which was a bit tatty. I'm of the mind that the guide pulley might be too close to the largest sprocket so I'm going to play with that...

Before you do, what happens if you change gear by pulling the cable rather than using the shifters (if you are able to do so)?

 

[jorgemartin]

Same thing... The chain remains on the large sprocket, doesn't mover and the whole thing vibrates and makes a bit of a racket...

 

[Angelfishsolo]

Same thing... The chain remains on the large sprocket, doesn't mover and the whole thing vibrates and makes a bit of a racket...

But it will move up the cogs OK using both the shifter and pulling the cable?

 

[jorgemartin]

From small to big sprocket, yes, it's going back that is the problem...

 

[Angelfishsolo]

From small to big sprocket, yes, it's going back that is the problem...

OK. I am wondering if the spring is damaged or struck. Have use tried lubricating it?

 

[jorgemartin]

Brand new derailleur. Just checked spring, looks lubricated and in good shape.

 

[Angelfishsolo]

Brand new derailleur. Just checked spring, looks lubricated and in good shape.

When you move the shifter does the dérailleur move?

 

[jorgemartin]

Doesn't move from big to small sprocket. Gets stuck there, on the big sprocket.

 

[Angelfishsolo]

Doesn't move from big to small sprocket. Gets stuck there, on the big sprocket.

Sorry I mean do you see any movement at all from the dérailleur when you move the shifter? What happens if you move the chain to the middle of the cassette and then back to the bottom?

 

[jorgemartin]

Yes, from the middle to the bottom works.