12-30 Rear cassette from an 11-28.

[antnee]

I don't seem to be able at the mo to get the pictures any bigger I need to read up on just how to load them differently as they were too big to start with so made them smaller then I must be able to load them as full image as have done it before But you can see the details failey well I think

 

[RecordAceFromNew]

Regarding the first pic the only thing I notice is that the gap between top jockey and your 30T is quite generous given the mech is probably stretched beyond spec. I would give it less B screw.

Regarding the second pic I don't think the large ring looks very worn. In any case a worn driving cog with a new chain meant chain suck, not skip - Jobst Brandt has an explanation for that on Sheldon's site.

Can't tell much from the third pic.

There can be numerous possible causes for your two potentially distinct issues of chain coming off when back-pedalling and skips when on the 11T. Apart from those mentioned above you might want to check whether there is any stiff link on the chain, whether any chainring sprocket tooth is bent out of plane, and finally for the 11T issue assuming the lockring is done up properly a loose/worn freehub.

 

[antnee]

Hi Re your comment on the first pic As to give it less b screw if I do that the jockey wheel catches on the 30T sprocket when on the 30T chainwheel.

I have checked the chain and it is new with a SRAM master link.

Re. the chain coming of when on 11T sprocket and 50T chainwheel I've just tried it on

Casette sprocket 11-12-14-16-18-20-23-26-30 comibinations and it only comes off on the 11T,12T, and the 14T from then on it stays on! I'm wondering now if its to do with the angle of the chain in relation to the chainwheel.

But that can't be so else it would happen to all bikes with more than about 6 rear sprockets wouldn't it (Sorry thats got to be pure bunkum!)

I don't think the freehub is loose but will check that tomorrow and while I've the wheel out will make sure the lock ring is fully tightened
One other thought did occur to me just now is that there is about a 1mm variration in the rotation of the 50T chainwheel on turning it when you align it with the front Derailleuer cage I'm unsure if this is due to a minutly bent BB spindle or the 50T chainring has a slight twist in one section? I supose its no trouble to remove it and place a straight edge across it thinking about it the 50 T chainwheel must have a slight twist in it as I can't see it when the the chain is on the 39T chainwheel or the 30T one though it being further away it's more awkward to see it properly.
Still perhaps this is something I can look at tomorrow as well.
Thanks for getting back to me as I't good to have someone to bounce ideas off. Cheers Antnee

 

[antnee]

it stayon after it on the 14 sprocket on! I'm wondering now if its to do with the angle of the chain in relation to the chainwheel.
But that can't be so else it would happen to all bikes with more than about 6 rear sprockets wouldn't it (Sorry thats got to be pure bunkum!) No it need not be as what about chain centre aglinement Should I try and (looking at the bike from behind) insert shims to eqate to the thickness of the extra sproket on the drive side and reduce the washers on the non drive side?

so then the cassette will be in the exact same place as it was when the freehub had the 8 speed cassette on Any body done this?
I can't see anything about it elsewear on the web but perhaps not looked hard enough yet.