Skipping chain/deraileur

Phinx

I'm having a major problem here. My deraileur (or chain) are giving me major headaches. Whenever i stand up to pedal at the same point every time, the chain seems to skip, although if i saw correctly while riding (only time i can replicate the problem), deraileur seems to get 'jammed', extend and then flip back. Same happens when i pedal while sitting, and still skips although lightly. Bike stays in the same gear.

This problem started when i put on a new 9 spd chain. No stiff links, i checked. Both front and rear cogs look in very good condition. I removed the magic link, since i thought it was the core of the problem, but no luck here either. gave it some cleaning as well so i don't think its the fault of dirt and grime.

Any ideas? I'm completely lost.

cooldad

Stiff link in chain? - waggle it sideways where you joined it.

Phinx

Got that checked straight after joining. Running smooth so the problem is something else.

Ro88o

Bent rear mech hanger ?
Too many links (mine takes 54 links - new chains usually have 58 ) ?
Stiff jockey wheels ?

Deputy Dawg

Worn chainring causing chainsuck?

Cferg

I've got the exact same problem having just fitted a new chain and I cant for the life of me work it out either. When Ive got the bike upside down its fine - the jumpings is almost non-existant but once I take it out and put the power through the cranks it jumps, while staying on the same sprocket ? :?

Matt 24k

Did it skip with the old chain?
If not then your cassette and or chainrings and possibly jockey wheels are too worn for a new chain and need replacing as well. A chain stretch measuring tool http://www.chainreactioncycles.com/Mode ... delID=5784 is a worth while investment as you can keep a regular check on stretch and replace the chain before it goes too far and takes the sprockets with it.

hardcorerider

It might also be worth checking your gear cables are clean and lubed ok. I had a simliar problem with chain jumping and skipping when I put the power down. I discovered it was due to the rear mech not springing as snappily as it should due to gunky cables. I cleaned all the cables, rear mech and cassette and have had no skipping issues at all. I initially thought it was a worn chain or cassette but turned out was just a gunky cable.

lordmerchant

Cferg wrote:

I've got the exact same problem having just fitted a new chain and I cant for the life of me work it out either. When Ive got the bike upside down its fine - the jumpings is almost non-existant but once I take it out and put the power through the cranks it jumps, while staying on the same sprocket ? :?

I'm having the same issue, and its driving me bat-shit crazy.
No Stiff links
No worn chain rings
tried swapping cassette out - problem still persists
new cable router and gear cable - Even tried a different shifter!
checked chainset were installed properly (so its all running straight)

and the problem persists only in highest three sprockets of cassette. All happened since I installed a new 9sp Chain (shimano HG93) which I have used dozens of times. Set the chain length to that of chain I was replacing (as always do)

Really getting on my tits now.

lordmerchant

...of Course it could just be that my H adjustment was too far out, and when I was putting the power down hard the mech could move too far over and cause the chain to slip off the jockey wheel :oops:

mr-brightside

ive also just had the same problem today i put a new shimano 9spd chain on and it just slips on the cassette so i have now put the old chain back on and it seems fine. the rear cassette looks ok i cant see any wear. how many miles should a cassette last?
the bike/cassette has done about 1200 miles should it last longer ten this?
should i just keep the old chain & cassette on and replace it all when it wont shift anymore?

PXR5

Just for info...

Check really closely that none of the teeth on the front ring are slightly damaged and have raised edges.

I spend quite some time trying to sort out a similar problem where the chain seemed to jam then release, but only ever in big (front) and two smallest gears at the back.

Finally tracked it down to just one damaged tooth on the front ring that had taken a whack from some rocks, the sharp edge meant that the chain just did not quite release properly.

Rather bizzarly you couldn't reproduce the effect in the garage with the bike upside down (don't have a work stand) so i put this down to tension in the chain whilst pedalling,

Once i'd filled off the edge of the offending tooth no problems, the only reason i can imagine it causing grief in these particular gear ratios would be just the very slight differences in the angles between chain and sprocket etc

sponsoryu

when I had this, the lockring wasn't tightened properly

blablablacksheep

heres a option, jockkey (the rear derail) their tooth might be worn?

d3matt

I had the same problem where the chain would slip when you stood up on the pedals, but fine when not under such high loads. Tried all sorts of things. Turned out to be a bent hanger, but by so little that it was hardly noticable, even when the old and new one was in your hand. It was only when I layed them in a particular way on the kitchen worktop that the bend was visable. A 1 or 2mm bend is magnified by a lot at the jockey wheels.
Try a new hanger. You're not wasting the money as you should keep a spare anyway. I get through one per month. :oops:
Also check that the derailleur is screwed into the hanger all the way. If its out by 1/2 turn, this has a similar effect.

Phinx

Lots of techniques to check out.

In my case, however, the skipping persists in all gears and even when i pedal whilst sitting down. My cassette probably has done no more than 300-400 miles. The front crankset got changed about 6 months ago in to Shimano M590. I never had this problem before changing the chain, but the rear cogs just don't seem to be that worn. I'll have a go at all the advices and see if i manage to do anything.

Phinx

Well, i'm still bikeless...i think i might give up and get it to an LBS, although the nearest thing is Halfords...

1) I checked for stiff links - none found
2) I took out the jockey wheels,, cleaned them and re-greased them them - no luck...
3) I checked the wear of rear cassette - the chain sticks to it like a glove.
4) Crank is also in a very good condition.
5) I re-tightened the rear cassette
6) I've retightened the mech
7) the hanger seem straight, i checked with a level-ruler

Last question...does the mech look bent to you?





I though jockey wheel must be in line with each other? The chain looks straight in to the first jockey whee; but then as you notice the rest of the mech is...under an angle?

d3matt

Difficult to tell with those photos but the derailleur doesn't look straight. As I said earlier, get a new hanger. You're not wasting money as you should have a spare anyway. I bet it is slightly bent. I've repeated experienced what you're getting and it is a small bend in the hanger, which gets magnified by the time you're at the lower jockey wheel.

Dirtydog11

Matt 24k wrote:

Did it skip with the old chain?
If not then your cassette and or chainrings and possibly jockey wheels are too worn for a new chain and need replacing as well. A chain stretch measuring tool http://www.chainreactioncycles.com/Mode ... delID=5784 is a worth while investment as you can keep a regular check on stretch and replace the chain before it goes too far and takes the sprockets with it.

This ^

Put it back on and see, if it doesn't slip then its the cassette and or rings.

Ro88o

Still looks slightly bent to me, it only has to be out a mm or 2 to give you problems.

I have had similar problems, dont worry about being a little forceful with it - give it some , they are designed to take the bend instead of your frame getting damaged.

I also agree with d3Matt about having a spare one.

you will feel the benefit immediately - bend it

Phinx

will do. Its either the hanger or derailleur. I'm guessing its the derailleur simply because the first jockey wheel is in line with cassette while the second is under an angle. I'll get a spare hanger and see how that goes, and if not - mech it is then.

Thanks for all the help everyone!

d3matt

Phinx wrote:

I'm guessing its the derailleur simply because the first jockey wheel is in line with cassette while the second is under an angle.

It's amazing what a tiny bend in the hanger can do. My hanger bends virtually every time I fall with the bike on that side....and I've been falling a lot while getting used to the clipless pedals. The top jockey wheel can look straight, but the lower one being miles off.......with Halfords hangers anyway!

Phinx

Now all is left is to find a replacement hanger. Haven't done that before so hopefully i won't mess it up. I guess i'll just need to go by shape.

anjs

I have seen this problem on Yukons as the gear calbe runs under the bb and when you stand up and compress the sus then you can stretch the cable and make the chain jump

Phinx

anjs

Unlikely. I'm not saying Yukons don't have this problem, but i rode this bike for a year and a half now, and nothing like that has happened before.