RD cage rotation/angle

[Fat Boab]

So to those in the know, some help would be appreciated.........

 

I've just fitted a 'new' drive train to a CX bike and am slightly concerned about the angle of the RD cage when on the largest sprocket. The RD changes and runs perfectly, and I haven't dropped a chain off the chainwheel (the FD is an attempt at a chain-guide but it can't be set low enough) but the cage just doesn't look 'right', and if its about to explode and wrap up in the rear wheel, I'd rather do something about it now. (PS I'm a roadie so MTD RDs are new to me....)

 

Context: 1x9 set-up, with 34T chainwheel and the RD is spec'd to handle a 34T largest sprocket. Current cassette is 11-32T. Chain-length was set-up based on biggest sprocket, bypassing the RD + 3 extra rivets. 

 

Thoughts? Am I worrying about nothing? If not, suggested remedies?

 

[Letum911]

I know nothing about these things but that does look a bit odd. However for as long as the top wheel in the derailleur is not touching the cassette I can't see it going horribly wrong.

 

Lets see what the more knowledgeable people say

[bertusras]

What does it look like on the smallest cog?

[Fat Boab]

What does it look like on the smallest cog?

 

 

[Quagga]

Add two links and it will be much better.....as is it will work, but you the spring is under unnecessary tension

[dirtypot]

Chain is a bit too short.  Another two links into it should sort it out.

[Fat Boab]

Extra 2 links, as in an inner and an outer plate, or 2 outer plates?

[Quagga]

 

Extra 2 links, as in an inner and an outer plate, or 2 outer plates?

 

1 link = 1 innner and 1 outer. add 2 outer and 2 inner to start with and see what it looks like on the 11 cog

[madmarc]

That chain looks too short.

[Sepia]

Lengthen it now before you stuff something up.  At least two links.... it will also change better.

Don't ride it like that.  

[Fat Boab]

And after 2 links added. Looks a lot better to me in both extremes.

 

Many thanks Hubbers!

 

 

[Fat Boab]

So if I'm trying to suss a rule-of-thumb, should I be aiming for angles to the vertical of the red lines shown to be similar, when in largest/smallest sprocket?

 

[madmarc]

Looks a lot better, but i'd add another link

[Capricorn]

So if I'm trying to suss a rule-of-thumb, should I be aiming for angles to the vertical of the red lines shown to be similar, when in largest/smallest sprocket?

 

chain angles.gif

 

if in big-big, you should still have some upward rotation of the rear mech. (you only need one or two links extra since there's no suspension travel that needs to be accomodated).

If the mech can't rotate anymore, then the chain is too short. How much upward rotation did you have left when your chain length was as depicted in the first post?

[TALUS]

Looks a lot better, but i'd add another link

Me too. Maybe adjust the B-screw then to prevent rub in the smallest gear (said with a tremor in the voice).

[TALUS]

Also I doubt you need to worry about chain retention in front. Those teeth look plenty long.