Could it be the wrong chain fitted?

[gavroche]

I collected my Giant Defy after having a new chain fitted. Went out tonight but soon realised there was something wrong.
1) .When on the big ring at the front, the chain is very noisy as I think it is robbing on the guide.
2). No matter what ring at the front or what gear on the cassette, the chain is slipping on the same sprocket every now and again which is very irritating as I dare not stand on the pedals.
My cassette has 11 gears and I think the LBS has fitted the wrong chain. What do you think?
In any case, the bike is going back at the end of week.

 

[JtB]

If you let your old chain wear too much then chances are the cassette is also worn and needs replacing.

 

[gbb]

JtBs suggestion sounds the most likely scenario.

 

[gavroche]

Thanks for your advice. It will be sorted this weekend .

 

[Cycleops]

I'm sure they'll check the front rings too.

 

[Vegan1]

Sounds like your drivetrain is worn regarding point 2.

 

[pclay]

If it's a Shimano chain, you need to check its on the right way round. They are directional.

 

[Ajax Bay]

1) Need to (re) adjust front derailleur (cable tension / limit screws).
2) This symptom is the classic (and only) indication that the cassette needs changing as well (as the chain), as @JtB has already suggested. Restrain from using the bike as much as possible till you have fitted the new cassette as running a new chain on a worn cassette will wear the chain disproportionately, as well as skipping on the most used sprockets - the latter both disconcerting and dodgy (eg pulling out of a side turning).
(If you could,) best immediate action is to put the old chain back on: why did you change it? But given the LBS did it, they will likely have ditched the chain. Note: worth asking the shop beforehand to bag up and give you the 'used' chain in these circumstances - for this particular and not unusual circumstance.

 

[gavroche]

I changed the chain and cassette ( Shimano 11x32) . Picking up bike tomorrow. £38 all together and should be ok for a long while yet.