chain slipping on two lowest cogs

mthams

hello,

I run 1x11, M8000 full XT setup. Under small load the chain is slipping (staying in gear) but only in the two smallest cogs. Chain and cassette is fine both relatively new done 1500km. Gear changes and in gears work fine on the stand.

Looking down the mech, cage does not look completely aligned and I wonder if that could be bent or the mech hanger?

Any thoughts to how to troubleshoot?

Many thx

cooldad

What happened/did you do between it working and not working?

mthams

I fallen off a couple of times..but worked until i tried to fiddle with the gears a bit and pushed a little to the mech cage as felt slightly out of line....wonder if that will be the mech hanger or cage which need to be replaced or just pushed into place?

cooldad

Depends which one you bent. Take the hanger off, put it on a flat surface, and see. But if you pushed, most likely the cage. Or you just indexed the mech incorrectly, if it was working fine. Why did you fiddle?

Things generally don't just push into place.

mthams

something was not straight and indexing couldnt fix it and gears were a mess.

I ordered a new hanger but wonder if it could be something else like the cage or where cage is attached to the mech?

frustrating not being able to use the two lowest cogs.

cycleclinic

Of the hanger is bent other gears will be affected mostly likely.

Given you seen so be taking the scattergun approach take the bike to shop. I would attempt to straighten the hanger first. If that improves matters then buy another one. Scatter gun approach to maintenance can be expensive.

glynrs2

It sounds to me like a derailleur alignment issue that I had.
I had an off going down on my driveside on slippery chalk. Unknowingly must have caught the derailleur, although looked ok. Gear indexing on my 1x12 Eagle was then off on just a couple of cogs/changes. Tried re-indexing, changing cable tension and did not work.
However, got out my derailleur alignment tool and it was quite a bit out of line. Got it all properly aligned and has been running perfectly since.
I imagine the 1x12 is very sensitive to alignment, as everything is so closely stacked. A 1x11 would be similar, but not quite so sensitive.

davee128

I'd check the hanger alignment, and also look at the mech alignment. If you've had a stack it could have got bent.

If the chain was new but the cassette isn't, that could also cause it. I've also seen this kind of slipping in high gears when a new chain is used on a worn chain ring. The slipping is actually occurring on the chain ring in this case but it is impossible to tell where it is really occurring. To check for chain ring wear, try pulling the chain forward at the front of the chain ring (half way around the wrapped part). You shouldn't be able to lift it much. If there's a significant gap under the chain and/or you can see the chain riding up the teeth at the top or bottom, you've found your problem.

mthams

Thanks for all the replies.

Is it not easier just to put a new hanger on? However to your point that other gears also likely to be off then maybe then maybe this is not he issue.

Bike shop said hanger is bent but just too a glance with the eye so I will try that.

I have added a new chain but cassette only some 1500km and when I put the old chain on, issue remained.

It could not be the cage which is bent where it’s attached to the mech?

larkim

Certainly new hanger is a relatively cheap and easily tested option. And having a spare hanger anyway is a good idea.

Not ideal, but even if the cage is a bit bent, providing the alignment of the upper wheel with the cassette is addressed (and that the lower section doesn't foul the spokes) broadly shouldn't that be OK? I suppose it depends on how parallel the motion is.

The Rookie

No, it wouldn't be OK, the mech parallelogram geometry is fixed and the guide wheel moves further away from the sprockets as you move to smaller sprockets (unless you started with the smallest large sprocket it was designed for)

So say the bottom of the mech is bent out and its all aligned to the largest sprocket perfectly, as you move to smaller sprockets the bend will mean it is misaligned slightly towards the next (larger) until it could/can be enough that the wrong gear is engaged.

larkim

OK, that makes sense. But if the bend happened to be on the cage between the two jockey wheels only, and doesn't affect the mounting point of the cage (and therefore the geometry of the parallelogram), would my assumption be correct?

The Rookie

Probably (though not for certain as there are a few variables involved) yes.

milemuncher1

The fact that it’s staying in gear, but the chain is slipping ( slipping rather than skipping) would tend to indicate that it’s more a case of the chain still being a bit stiff, and it’s skipping over the teeth on the sprocket, or that the chain and cassette haven’t ‘meshed’ fully yet. It can’t hurt to do a hanger alignment / replacement, but I find the chain will tend more to skip, than slip if there’s an issue with alignment. I’ve also found slipping happens when the jockey ( tensioner ) pulleys get a bit worn.

Brakeless

Milemuncher1 wrote:

The fact that it’s staying in gear, but the chain is slipping ( slipping rather than skipping) would tend to indicate that it’s more a case of the chain still being a bit stiff, and it’s skipping over the teeth on the sprocket, or that the chain and cassette haven’t ‘meshed’ fully yet. It can’t hurt to do a hanger alignment / replacement, but I find the chain will tend more to skip, than slip if there’s an issue with alignment. I’ve also found slipping happens when the jockey ( tensioner ) pulleys get a bit worn.

A new chain is not 'stiff'. A chain gets stiff if it is not lubed properly as it gets older not when new. Jockey wheels will rarely have anything to do with a chain slipping as they don't take any pressure, all pressure is on the chain rings and cassette..

milemuncher1

Brakeless wrote:

Milemuncher1 wrote:

The fact that it’s staying in gear, but the chain is slipping ( slipping rather than skipping) would tend to indicate that it’s more a case of the chain still being a bit stiff, and it’s skipping over the teeth on the sprocket, or that the chain and cassette haven’t ‘meshed’ fully yet. It can’t hurt to do a hanger alignment / replacement, but I find the chain will tend more to skip, than slip if there’s an issue with alignment. I’ve also found slipping happens when the jockey ( tensioner ) pulleys get a bit worn.

A new chain is not 'stiff'. A chain gets stiff if it is not lubed properly as it gets older not when new. Jockey wheels will rarely have anything to do with a chain slipping as they don't take any pressure, all pressure is on the chain rings and cassette..

I used to think you didn’t have a clue, now I know. You’ve obviously never had a brand new chain out of the box, they tend to be pretty stiff, you’ve obviously never experienced what happens when jockey wheels wear out ( I’ll give you a clue, the chain starts to slip ) oh, there you go I’ve told you. Why bother trying to contradict me, when it’s obvious you don’t have any experience? You’ve never heard of a ‘stiff link’? Obviously not. Jockey wheels ( tensioners, the clue’s in the name) don’t do their job very well when they wear out. Go and ride a bike for a few hundred thousand miles, then come back and tell us what you’ve found out.

glynrs2

A stiff link is certainly worth checking for. That would be most noticeable on the smallest cogs, as the chain is having to flex around a tighter radius. If you have a Shimano chain that you have to press a new pin through to join, this can happen if you have pushed the pin through slightly too far and caused it to pinch the roller. You can try very gently backing that pin a tiny degree at the stiff link by using your chain tool in reverse (from the other side of the chain) - if you see what I mean.

mthams

guys,

update but issue still appear NOT fixed.

I have changed the hanger, NO FIX, maybe a touch better but i will ride it to work tomorrow to be sure....i found I have been running the hanger without the little extra screw which secures it so I am glad that replaced it anyway.

it should be noted, I run a KMX 11S link on the KMC chain...I did that on the Shimano chain too -> both slipping as i put the shimano chain on to double check.

I also noticed that the upper limit (Largest cog) the screw does not have tension anymore at the limit to reach that cog.

What will you recommend is next step? I can get a new derailleur no problem as im getting a little fed up with the issue but i would of course love to find the root and love to be able to fix it myself.

next step?
- derailleur alignment tool (thats not doing anything to the hanger right???)
- change the cage?
- can the mech be bent? (is that a new derailleur?)

Thanks for your help in advanced!!!

glynrs2

Next step: get local bike shop mechanic to look at it

mthams

my morning right, definitely improvements in the second from lowest cog but lowest cog still slips but 100% there is an improvement but not solved.

Anyone with some thoughts with the additional info i gave in my post just before this?

Best

cooldad

mthams wrote:

guys,

....

I also noticed that the upper limit (Largest cog) the screw does not have tension anymore at the limit to reach that cog.

What will you recommend is next step? I can get a new derailleur no problem as im getting a little fed up with the issue but i would have course love to find the root and love to be able to fix it myself.

next step?
- derailleur alignment tool (thats not doing anything to the hanger right???)
- change the cage?
- can the mech be bent? (is that a new derailleur?)

Thanks for your help in advanced!!!

The lower limit screw adjusts for the large cog. Lower as in lowest gear.

But it's impossible to say. It could still be anything.

mthams

cooldad wrote:

mthams wrote:

guys,

....

I also noticed that the upper limit (Largest cog) the screw does not have tension anymore at the limit to reach that cog.

What will you recommend is next step? I can get a new derailleur no problem as im getting a little fed up with the issue but i would have course love to find the root and love to be able to fix it myself.

next step?
- derailleur alignment tool (thats not doing anything to the hanger right???)
- change the cage?
- can the mech be bent? (is that a new derailleur?)

Thanks for your help in advanced!!!

The lower limit screw adjusts for the large cog. Lower as in lowest gear.

But it's impossible to say. It could still be anything.

yes lightest gear largest cog

mthams

any suggestions besides take it to the local bike shop...?

milemuncher1

Try winding the L screw a little bit clockwise ( think clock out) to move the mech slightly towards the next smallest sprocket ( higher gear ) and wind the indexing screw as far clockwise as you can Then shift all the way to the smallest sprocket ( highest gear ) and then change to the smallest chain ring ( front shift low ) Release the cable clamp bolt, on the rear mech, and give the cable a little tug, with the cable held tight, re tighten the clamp bolt on the mech, and put it back to big chain ring, then shift back towards the largest sprocket. When you get as far as you can, if it’s still not going over the biggest sprocket, try seeing if you can get it to go by rotating the indexing screw counter clockwise, if not, carefully screw the L screw counter clockwise, until it stops, or the chain makes it over the largest sprocket. I’ve had situations in the past, where the little release and cable tug trick has got the result, even though the cable didn’t seem to be noticeably jammed ( by feel anyway). Then just do a standard re indexing.

larkim

Wouldn't it be more simple to just say "Re-index, but make sure you've given the cable a firm tug first as sometimes it's can get a little stuck in the cable outer and this can free things up"?