rubbing chain

[whoof]

I put a new chain and cassette on and the new one now rubs on the rear derailleur cage as it comes in from the chainring. Everything worked perfectly well before I changed the chain/cassette. If I move toward the smaller sprockets there is a gap between the chain and the mech but as I move to larger sprockets it starts to rub. It does this in all three chainrings.
Please see pictures below with red arrow showing gap (camera focused on a different point so it's a little blurred).

The picture below gives an indication of chain length and shows the chain in; 1) largest chainring/smallest sprocket and 2) Largest chainring/largest sprocket (which I would never use).

It's a 10 speed triple Tiagra groupset the only variation is the new 10 speed KMC chain. I've checked that the hanger is not loose on the frame or the mech loose on the hanger.

Any ideas?

Many thanks.

[Brucey]

if you took the pulleys out of the mech, did you note that they are not the same as one another and that the lower pulley may only be fitted in one direction?

cheers

[whoof]

if you took the pulleys out of the mech, did you note that they are not the same as one another and that the lower pulley may only be fitted in one direction?

cheers

Thanks, I'll take a look at the jockey wheels this evening. They have never been out of this mech but I'll take them out, put them back again and see what happens.

[NATURAL ANKLING]

Hi,
I have a similar problem on all new kit.
Not got to the bottom of it yet.

Chain line?
Chains also have different outer plate profiles, so not all chains may be quite?

[Brucey]

if you took the pulleys out of the mech, did you note that they are not the same as one another and that the lower pulley may only be fitted in one direction?

cheers

Thanks, I'll take a look at the jockey wheels this evening. They have never been out of this mech but I'll take them out, put them back again and see what happens.

They are marked upper and lower, and often the lower pulley will fit one way only (there is a rotation direction marked), but It may be that the pulleys are knackered. They don't last for ever; IIRC there should be about 0.5mm float in the top pulley (and no wobble) and there should be neither float nor wobble in the lower pulley.

It could be that the old chain was quietly gouging away at the mech for months, and the new chain is a slightly different shape so makes contact in a new, noisier, way.

cheers