Rear derailleur...which screw to adjust?

[Mazz]

Firstly I would check how tight it is on the large chain ring to large cog, also check how stretched the rear mech is, if there is some capacity, then I would shorten the chain slightly. It won’t need much, just enough to stop it running on the jockey wheel.

Nice one, I'll give this a try.

I must admit, by the sound the chain/mech makes when I change gear (particularly moving up the gears), I hear a kind of "slapping" noise. My guess is that the mech's taking up too much chain slack.

If the chain has a quick link remove it and check the chain length big-big without being through the derailleurs.

Yes, it's an SRAM chain with a quick-link.

 

[roubaixtuesday]

Thing is, if I remove a paired link, is there a risk the chain will become too short and cause damage, like @roubaixtuesday says?

Yes, there's a small risk, but as per advice above, put it on big/big, then see whether it looks like you can shorten. You can even scrunch it up to simulate a link being removed if you're not sure.

I would be 95% sure it'll be OK. but it's always worth checking before you ride it and put it under load.

 

[presta]

Thing is, if I remove a paired link, is there a risk the chain will become too short and cause damage, like @roubaixtuesday says?

Yes. You've said above that you put a bigger sprocket on when you changed the chain, so if you use the same length of chain you may well find it's no longer long enough, and as others have pointed out, if you engage big-big whilst riding with a chain that's too short you'll wreck your transmission.

If you've not got enough scope for reducing chain length, then the rubbing you're now seeing is caused by the fact that the rear derailleur doesn't have enough capacity for the new gears you're using.

 

[Mazz]

Yes, there's a small risk, but as per advice above, put it on big/big, then see whether it looks like you can shorten. You can even scrunch it up to simulate a link being removed if you're not sure.

I would be 95% sure it'll be OK. but it's always worth checking before you ride it and put it under load.

Nice one - I like the 'scrunch it up a bit first' suggestion.

 

[Ajax Bay]

Nice one - I like the 'scrunch it up a bit first' suggestion.

What I'd do.
But would be useful to get some facts: number of teeth on how many chainrings; cassette range (ie 11-30t) and make/model of derailleur.
If its specified wrap capacity is being exceeded (which I reckon is likely from the info snippets upthread) interference in small/small is very likely, if the chain is long enough to go large/large, as it must be.
If you get the chain/chain noise (in small/fairly small) it's an easy jolt to just shift to a larger chainring.
And ride on.

 

[presta]

Nice one - I like the 'scrunch it up a bit first' suggestion.

Yes, there's no need for dismantling anything, just put it on big-big, and then see if you can pinch enough chain together to remove a link pair.

 

[Mazz]

But would be useful to get some facts: number of teeth on how many chainrings; cassette range (ie 11-30t) and make/model of derailleur.

Chainring Shimano 50-34
Cassette Shimano 11-34, 10-spd
Rear derailleur Tiagra, medium cage
Front derailleur - not sure off-hand, probably Tiagra

 

[raleighnut]

Chainring Shimano 50-34
Cassette Shimano 11-34, 10-spd
Rear derailleur Tiagra, medium cage
Front derailleur - not sure off-hand, probably Tiagra

You would have to know chainstay length too to enter the info into a calculator then start counting links.

Far easier to wrap the chain around big-big (not threaded through the mech) and make sure the 2 ends overlap by a link then refit the quicklink

 

[roubaixtuesday]

Chainring Shimano 50-34
Cassette Shimano 11-34, 10-spd
Rear derailleur Tiagra, medium cage
Front derailleur - not sure off-hand, probably Tiagra

This one? https://bike.shimano.com/en-EU/product/component/tiagra-4700/RD-4700-GS.html

Capacity is quoted as 41T, you need (50-34)+(34-11) = 39, so you should be fine.

 

[Mazz]

This one? https://bike.shimano.com/en-EU/product/component/tiagra-4700/RD-4700-GS.html

Capacity is quoted as 41T, you need (50-34)+(34-11) = 39, so you should be fine.

Yes, that's the one.
I should be fine what? removing a paired link?

 

[roubaixtuesday]

I should be fine what? removing a paired link?

Yes. But do check big/big before riding!

 

[Alex321]

Yes, that's the one.
I should be fine what? removing a paired link?

There was some doubt about whether your derailleur was designed to have enoiugh capacity to cope with the range of gears you have.

He was saying that aspect should be fine.

 

[Mazz]

There was some doubt about whether your derailleur was designed to have enoiugh capacity to cope with the range of gears you have.

He was saying that aspect should be fine.

Ah cheers for the clarification.
Yes, that was the subject of another thread - when I wanted a cassette with lower gears on it....in the end, I had to also replace the short-cage with a medium-cage rear derailleur (the short cage wasn't up to the job).

 

[Ming the Merciless]

Have you done the check now?

 

[Mazz]

Have you done the check now?

This is what the chain/mech looks like when on big-to-big...