Rear derailleur rubbing chain.

plasma_man

Hi all

A few weeks ago I changed my rear 10 speed cassette to one with a bigger low gear to help with climbing. I also changed the chain.

Setup the gears, adjusted the B screw, done a few km's to test and all ok. Then while doing some fine adjustments a few days later, I noticed that going from 3rd to 4th, the chain rubs the derailleur arm just as it moves between the cogs. It's easy to see, but you don't hear or feel anything when riding. The arm had a few chunks of metal out of it so I think it may have even been rubbing on the old cassette.

So far I have changed the rear hanger, I had a couple of spares so wanted to rule it out. It helped a little actually. Adjusting limit screws or B-screw does not change the distance of the arm to the chain, I also filed the arm a bit to take out he rough patches, and now the chain is just brushing against it at this point. I could live with it like this, but it's nagging me!

What are my options, I would be quite happy to put on a new derailleur which has a different design and gives more clearance, I would need some advice on what to buy to be sure it would help, otherwise, something I have done wrong or an adjustment I have missed?

Cheers

cobba

Post a side on photo of the derailleur.

What's the derailleur and is it rated for the cassette that you are using?

JGTR

If it's not causing an issue I'd say leave it

Rightarmbad

Undo rear derailleur bolt a tiny bit , turn derailleur down to where it is meant to be and do it back up.
The link is in the incorrect place and is not seated on the dropout tab.

And new hangers are not necessarily straight and usually are not.

Cubehead555

http://www.parktool.com/blog/repair-help/rear-derailleur-adjustment

plasma_man

Hi all.

Sorry for not getting back, thanks for all the advice so far, but nothing has helped.

The setup video doesn't help with this problem, the derailleur arm is miles away from the cassette.
B-screw tuning does not adjust this gap.
The hanger and derailleur are installed correctly, there is no other way to put it on, the lugs are sitting against eacher other. The only adjustment possible is to make it worse, not better.

Here are a few more pictures. The cassette is NON standard, I swapped it out recently, from a 11-36T to a 11-40T, maybe the design of the arm is just not suited to these bigger sprockets.

larkim

Suspect it's just the derailleur model as I think you mention earlier.