Rear Derailleur problems

NeedMoreGears

I had been getting a little noise/roughness when pedalling. I found the chainrings and chain had become quite worn so I replaced chain, cassette and chain rings. Everything nice and smooth for a while and then the chain started to jump a little as if it was skipping over cassette or chain ring teeth - this tended to happen under medium load.

So I put the bike in a stand and moved the pedals. It seems that the rear derailleur was catching & releasing the chain every now and again - quite gently but definitely there. There seemed to be no problems on the chainring or cassette.

The upshot was that it finally caught up on itself none-too-gently and the mechanism jammed up causing the hanger to fail.

When I changed the cassette I went from a 12-26 to an 11-30 (for shame I know but it was the only I could continue without a triple). To allow for this I left two extra links in the chain over the original on the basis that only half the cassette is in contact with the chain (30-26)/ 2 = 2

Questions:

1 - anybody know what's causing this

2 - am I better to replace the whole derailluer and not just the hanger

3 - should I take out the two extra links

Any help/suggestions greatly appreciated

NMG

AstraMonti

Not an expert (far from that) but few questions that popped in my mind:

Do you have a long cage? Is the cassette properly installed? Have you readjust the rear derailleur to accommodate the change of the cassette? How old are your cables?

cdaly_

The other thing that comes to mind is a tight link in the chain. That might give you an occasional hop...

Karma

If youclean the jockey wheels in the rear mech, you will see if the jockey wheels are worn down. you should be able to see if it is the chain, or the mech or if there is not enough of a gap from mech to cassette.
(sometimes) you would have to adjust the final positions of the mech if you change the cassette size.
there are high and low positions for the mech and a screw under the mech to hold its angle off the back of the dropout.
show us a pic

bcmf

How old is your RD? As above sounds like a stiff link on the chain or worn jockey wheels on the mech itself.

Based on this-> 'It seems that the rear derailleur was catching & releasing the chain every now and again - quite gently but definitely there. There seemed to be no problems on the chainring or cassette.' I would put the bike back on the stand.and find out where the chain is jumping then just give the link that is sticky a 'push'

NeedMoreGears

Thanks everyone

Based on what you guys have said, I think I probably need to adjust that screw at the bottom of the derailleur first and if I'm still having problems, then I'll head for the LBS and sheppishly ask them to fix it.

8kvscdpglqnyr4

cdaly_ wrote: »

The other thing that comes to mind is a tight link in the chain. That might give you an occasional hop...

From what you have described, I'm thinking cdaly has hit the nail on the head. I had the exact same symptoms as yourself and it turned out to be a tight link in the chain.

It really took a while for me to see what was causing it as it is the last thing I looked for. I checked everything else first!