New chain jumps in 8th sprocket. *IMAGE*

richardjiles

So I just bought a new chain, put it on my bike and as usual its too big, so I pulled out my chain splitter. But OMG! The thing is so fucking tough to split, I can't do it, and I'm afraid ill break my tool!
The chain is a Sram PC-850

UPDATE:
The chain is no sized correctly, but I still have this problem with the chain 'jumping', it only happens on the last gear (gear 8) smallest sprocket. and it does it constantly, even when im applying little pressure, I looked at the teeth and they are just fine, plus i just replaced cassette so it would be

supersonic

Make sure the chain tool pin is right in the centre of the chain rivet, or it will be a bugger! Sometimes they take some turning.

richardjiles

supersonic wrote:

Make sure the chain tool pin is right in the centre of the chain rivet, or it will be a bugger! Sometimes they take some turning.

GOT IT! just put a cloth over the handle so it didn't hurt my hands while pulling

supersonic

As for the skipping, may just be a slight adjustment problem - but the cog could be worn, and not liking the new chain.

richardjiles

supersonic wrote:

As for the skipping, may just be a slight adjustment problem - but the cog could be worn, and not liking the new chain.

All the gears are adjusting properly, I just re aligned it, however I did put the cassette on before the new chain- about a month time difference, so will the chain adjust to it?

richardjiles

Does anyone know if the 8th cog will adjust? or the chain will adjust?

nicklouse

i would say you have the wrong lock ring on. and it will not work with a 11T cog.

The Rookie

Agreed, looks like the chain side plates are running on it and lifting the chain off the teeth.

Simon

richardjiles

The Beginner wrote:

Agreed, looks like the chain side plates are running on it and lifting the chain off the teeth.

Simon

Alright, thanks for the advice!!! I do have a spare lock ring, I can put that on, take a picture, then update you guys on whether it jumps or not.

richardjiles

okay I put this new lock ring on, not a single difference was giving.....
Just a note, 7th gear works with no problems at all!
take a look:

benpinnick

Have you checked for stiff links?

StefanP

Have you checked the 11t is sitting properly "seated"? (Although it looks like it is)

richardjiles

StefanP wrote:

Have you checked the 11t is sitting properly "seated"? (Although it looks like it is)

Yup, I ran it on the bike repair stand and it runs fine

richardjiles

benpinnick wrote:

Have you checked for stiff links?

While looking at the chain on the repair stand I cant see and stiff links, there are no strange movements on the rear deraleur so i will assume there aren't any.

supersonic

Check the H screw is properly adjusted.

richardjiles

supersonic wrote:

Check the H screw is properly adjusted.

yup, first thing I did when adjusting the gears

TBH, this thing is just stumping me, because it doesnt look like its worn down too much, new chain so its no like the chain is stretched! and the cassette is relatively new. And it only happens in gear 8

baznav73

If there is nothing else obvious then it is definatly wear on that sprocket, the origanal lockring was the correct one it' a sram cassette and they come with that lockring, looking at the picture there do seem to be some small burrs on some of the teeth indicating wear.

supersonic

Try cleaning the cables and making sure they are well lubed. Check gear hanger is straight.

richardjiles

supersonic wrote:

Try cleaning the cables and making sure they are well lubed. Check gear hanger is straight.

Cleaned the cabled etc, the hanger APPEARS to be straight.

sparky.2002

It's not a wipperman chain is it?? I had that problem until I put the quick link in the other way up.

richardjiles

sparky.2002 wrote:

It's not a wipperman chain is it?? I had that problem until I put the quick link in the other way up.

Nope its a sram pc 850

Splodger

Are you really really really sure you have the mech properly adjusted? If it is jumping under little load, this is the most likely.
Is the end stop correctly adjusted and allowing the chain to move all the way onto the sprocket? It could be trying to jump up onto the next gear all the time.
Also, make sure the cable is letting the mech move all the way onto this stop.
From the pics the sprocket didn't really look worn.
How long is the chain? You only want it to be 2 links longer than the distance around the biggest chain ring and biggest cog at the back.

richardjiles

Splodger wrote:

Are you really really really sure you have the mech properly adjusted? If it is jumping under little load, this is the most likely.
Is the end stop correctly adjusted and allowing the chain to move all the way onto the sprocket? It could be trying to jump up onto the next gear all the time.
Also, make sure the cable is letting the mech move all the way onto this stop.
From the pics the sprocket didn't really look worn.
How long is the chain? You only want it to be 2 links longer than the distance around the biggest chain ring and biggest cog at the back.

explain how i take the length in detail, am i still running it through the deraileur?

richardjiles

New picture! Also check out this video, it shows that all my gears are working right in the repair stand, gear 8 is fine in this, no jumping up a gear.




http://www.youtube.com/watch?v=IiVEHwqQnng

benpinnick

Hard to tell from the piccy or video, but a couple of questions:

Looks from the picture that your running granny to high on the back. This will never work - is this the case?
Your mech seems to be hanging quite low. You might want to ease off the B tension screw a little.

nicklouse

top jockey wheel is too far from the cassette.
hanger/mech looks bent (could be camera doing that).

what gears was that in?

you did size the chain correctly?

what bike?

Splodger

Richard, to get the chain length right, run it around the biggest chainwheel at the front and the largest cog at the back. (This is the worst possible gear selection you could use that will make the chain length critical). Then just allow two links extra at the overlap and this is the length your chain should be when fitted (you will need to make an allowance for the quick link if you use one - ie one link length).

If you are in the smallest gear at the back, you don't want to be in the smallest at the front too. The chain ends up running at an awkward angle between the gears and could cause jumping. It will definately wear your chain out quickly.

If you move to the largest cog at the front, and smallest at the back, does it still jump?

My gut feel is that it is an adjustment problem still if the chain is jumping on low load. Try undoing the cable (or slackening the adjuster right off) and then winding the stop adjusting screw out further to see if it stops the jumping.

Horton

richardjiles wrote:

explain how i take the length in detail, am i still running it through the deraileur?

Don't run it through the derailleur , just round the largest ring and largest sprocket combo, then add links as previously posted.

But I'd agree with what Nick said, the jockey wheel looks too far from the cassette so you should adjust the tension screw to move it closer and see if that helps, although it does look like something is a little bent judging by the last photo.

richardjiles

benpinnick wrote:

Hard to tell from the piccy or video, but a couple of questions:

Looks from the picture that your running granny to high on the back. This will never work - is this the case?
Your mech seems to be hanging quite low. You might want to ease off the B tension screw a little.

The granny gear does work, hope this helps

richardjiles

UPDATE: The chain is properly lengthened, unfortunately i cant test it as there has been a recent spell of snow and rain over here
will test it soon

Horton

I think what Ben meant was you shouldn't be running granny ring on the front and smallest sprocket on the back (likewise big to big is a no no) The chainline is too extreme and can lead to the chain catching which isn't always apparent on a stand as relatively little pressure is being put through the system. These combos can also cause more chain wear and are normally gears that can be replicated with a better choice of chainring/sprocket I.e. small/small is a similar ratio to middle/middle but the latter gives a far straighter chainline and has more tension in the chain as the derailleur will be pulled forward so it's less likely to skip and jump as the bike bounces around.

Of course the above is only relevant to you if the problem you're having occurs when in small/small combos...