figured it out

You shouldn't be using that combination.....The drill however is to shorten the chain just enough that there is no rub when in that combination......Then,assuming you are using the correct derailer for the application,it will handle the large cog for the recommended application. But always check to be certain the chain is also long enough for the big/big.

What do you have for a cassette? What do you have for chainrings?

Thanks for the replies people...

CASSETTE
Shimano HG-50 LX, 9-speed, 11x34t

CHAIN
Shimano HG-73

FRONT DERAILLEUR
Shimano M-570 LX, 34.9mm clamp, bottom pull

REAR DERAILLEUR
Shimano M-750 XT, long cage, standard spring

CHAINRINGS
44Ax32Sx22S, 4 bolt 104/64mm pattern, steel chainring bolts

When you say I should not be using this combination are you referring to that when biking I should try to avoid using this specific gear (i.e. cog and crank) combination?

(That is of course assuming everything in the drivetrain is compliant?)

thanks again for the reply..

I was wondering if a road triple crank 53-39-30 and an mtb cassette 11-34 might create too much slack in 30x11 if the chain is long enough to work in 53-34. I know you should not cross chain, I was just wondering if that combo might cause a problem? I know a couple of people who have this problem and have this gearing, but I have not looked at the bikes yet.
What do you think?

That is correct. With a triple there is no point in using the smallest cogs whrn it the small ring, or the biggest cogs when in the big ring. It just increases stress and wear on the drivetrain.

That is 42 teeth of wrap and within the capacity of a proper mtb RD. Even if wrap is a bit insufficient,the answer is to stay out of the small cogs when in the granny ring.However,this concept seems to be lost on far too may people that think they should be able to use every gear combination.

Thank you sydney. That will be helpful. :)

edited.......

Remove one link

Given the components you listed, you are dealing with 45 teeth of required wrap.That is 2 teeth outside of the 43 tooth spec. Shimano spec is usually conservative.The derailer really should handle it,but your chain may also be too long.Put chain on big big and see if there is enough enough extra chain to remove 1". If not then there is nothing to do but sstay out of the smalller cogs when in the granny as I already said.

When I check chain length, I do two things.

I put the chain into the big-big gear combo and set length so as to not over stress the derailleur.

I then go to the small-small combo and try to avoid the chain rubbing the upper jockey pulley as you are experiencing.

Of the two, rubbing the upper jockey pulley is the safer option. IOW, leave the chain longer.

Even though everyone knows to not cross chain while riding, (BIG-BIG or SMALL-SMALL) in the event you accidently do it, it's better to have the BIG-BIG combo NOT over-stress the rear derailleur vs. a little bit of harmless rubbing.

Did that make sense?

works for me.

edited..

Actually is isn't. It all depends on the tooth spread and derailer being used. I don't have that isssue with any granny setup I have.I even have short cages that wrap all the chain even with a granny and the small/small.... Just curious...Do you really work in a bike shop?

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edited....

Honest quiesion I think considering your alleged 'credentials' and the 'stuff' you dish up.

I believe one other way to handle large tooth spread is also to use larger rear derailleur pulleys and you can have a shorter cage. Like my 3x9 Dura Ace. I think some of the hybrids, with mega range do this too, ???

Correct me if I am wrong. I may be way off base, I'm thinking.....

Typical road triples need less wrap than typical MTB triples? Closer ratios. Just more typical,
not every single case. So it's more typical to get a short cage working well on a road triple.

Is this correct?