[Closed] Why is this rubbing?

Um, should it be the other side of that plate in the middle?

Agree, chain routed incorrectly! But I'd not worry, it looks like it only needs a few more miles before it grinds off that pesky tab 😉

Christ that must make a racket as you're pedalling along 😁

Always a joy to spot that one.

We've all done that (haven't we?).

I'm wondering why all the adonising has disappeared off the top edge of the cage though.

It's routed as Shimano suggest.

Aftermarket lower jockey wheel that's too small? (Or jockeys in the wrong way round, upper swapped with lower...)

Yep, I've definitely done it. I usually spot it (hear it) within a few pedal revolutions though.

Kudos for riding it a while like that, it's going to be like having a new bike once you sort it.😁

EDIT: I take it back, that is odd!

I'd like more pics tbh, it's a recent Shimano mech, 11 speed XT maybe? Been in bits?

The bits we can see all look OK but just trying to guess the angles from what we can see, it's almost like the top jockey is in the wrong place

Is the bit its rubbing bent? It is normally at 90 degrees to the side plate. From that picture it looks like it may be bent more like 45 degrees. As the picture shows the chain looks to be rubbing more on the side nearest the camera.

Did you get a stick or something jammed in the mech and then it start rubbing after that?

Thered the picture on the right shoes you how to do it wrongly, the one on the left is the right way.
The 🚫means stop, or wrong.

Chain too long? The pivot point is not on the same axis as the top jockey wheel on these mechs are they?

When the chain is at it's slackest (as in the photo) the top jockey wheel is kicking it out and down towards the plate. take a couple of links out, the cage 'shouldnt' swing back that far in the smallest rear sprocket then.

Edit: I've changed my mind, I don't think it's that now.

what mech is it? has it had new jockey wheels fitted?

Thered the picture on the right shoes you how to do it wrongly, the one on the left is the right way.
The 🚫means stop, or wrong.

I think you need to relook at the original photo.

It has been installed correctly the routing of the chain does not appear to be at fault.

Agreed fettling i don't think its that because the jockey wheel pivots remain in the same relative opition to each other as the top one rotates around the cage pivot.

has the top jockey been worn to a disk? it should have quite distinct teeth shouldn't it?

@joshvegas yep, after i posted my brain woke up! they will move relative to each other.

Top jockey too big/bottom jockey too small would give the rubbing in the picture, what is weird is the anodizing rubbed off the back of the cage plates, something is odd.

More info required...

Is the cage rotated correctly? It looks like it might be rotated too far backwards to me.

As fettlin pointed out the position of the cage is irrelevant to that bit hitting the chain.

I dont get it.
Better pics I think needed

Chain too long?

Edit: I’ve changed my mind, I don’t think it’s that now.

why? thats my first thought, the chain is too long allowing the mech to spring too far back.

i dont actually understand that right/wrong pic, as theyre both routed the same way, its just with one of them the chain doesnt seem to mesh on the teeth correctly.

but yes, my answer is chains too long. has it been set up by placing on large/large, disregarding mech, then adding 2 links (as per the diagram above the right/wrong pic)?

i dont actually understand that right/wrong pic, as theyre both routed the same way, its just with one of them the chain doesnt seem to mesh on the teeth correctly

The one on the left (the correct way), the chain is routed above the tab marked 'A', whereas the one on the right the chain is routed under tab 'A'.

I think in the OP's photo the tab A looks bent, causing it to rub and the chain.

I agree we need more pics. If the routing is correct, the jockey wheels are wrong or heavily worn (they don't look it though), or you've somehow managed to bend the tab as others have suggested (which it does kind of look like).

Routing is correct. That tab that it’s rubbing on is bent upwards for some reason. Should be at a right angle to the back plate.

I’d just bend it back and it should be fine.

@sadexpunk the jockey wheels don't move independently to each other, they are both fixed to the same cage so regardless of chain length (and cage angle) the path of the chain doesn't change through the mech body.

If it rubs with the chain on the smallest sprocket it will rub when on the largest as well (as long as all other factors are as they should be, obvs).

Logically, that bottom jockey wheel should be bigger. And in the shimano diag, it looks bigger, too.
So Pyro had it right up there ^^^^ - bigger jockey wheel will lift the chain away from the tab.

Looks like that tab has been bent upwards on the end. Bend it back down and I think it’ll be all good.

If the chain was too long it wouldn't make a difference between the jockey wheels, but the chain is humping up and resting on the tab, we need a photo to include both jockey wheels and more side on. Is it an SLX.
Chain is right, tab looks bent up.

11s mech, 11T jockey wheels?

Weird, my brand new GRX812 rear mech had some wear on that tab too, no obvious rubbing or noise coming from mech and I agree that the routing shown above is correct.

On both my XT 11sp, there's loads of space between the chain, so even if I did bend it it probably wouldn't rub chain.
I'd be checking jockey wheels too.

Jockey wheel looks small and on its last legs, teeth are well worn. The upper one is probably worse, but there seems more to it than that.

It looks like its about to sort itself out soon though so just bash so just bash on for a sudden boost in performance mid ride.

Looks like the top jockey wheel might be too big, has someone fitted the wrong new jockey wheels, if the top wheel was too big then it would have that effect (and probably the same effect if the lower jockey wheel is too small)

Where's the OP? WE NEED CLOSURE!

Probably not going to return as the first responders couldn't even agree on how to thread the chain correctly.

obvious solution is to break the tab off - what does it actually do anyway?

obvious solution is to break the tab off – what does it actually do anyway?

it appeals to the japanese sense of humour.

I only just spotted that he poster is Thered. He's got previous! I remember about 6 years ago on a night ride on Cannock Chase the very same thing happened to him. Somehow, mysteriously, the chain managed to jump the tab on his XTR or X0 9speed mech.