New Chain Slipping

jp1970
jp1970 Posts: 134
edited January 2013 in Workshop
Last night I replaced the chain (on my 8 speed Sora Groupset), this morning during my commute the chain was slipping under slight power/load on each pedal turn !!! this was happening across the cassette and all chain rings. The gear indexing appears to be OK as the chain is being moved across the cassette when shifting up & down.

As i was unable to ride safely I replaced the new chain with the old chain, this did not completely resolve the slipping problem as it was still occurring albeit slightly less frequent and under more load.

Having now compared both chains it appears that the roller width on the new chain is slightly narrower than the old chain.. I haven't had chance to properly compare the new chain against the old chain. I think the LBS have sold me the wrong chain ( I did ask for a 8 speed chain - The new and old chain is KMC)

On the basis that the new chain is the 'wrong one' .. I'm slightly baffled why the old chain is now slipping. No links have been removed when i removed it, also the replaced pin is sitting flush.. I rechecked .. .


Have i missed something.. ? Do i need to adjust the cable barrel on the rear derailleur ? or is it a stiff link ??

Thanks in advanced

Comments

  • Was the previous chain quite old/well used?
    If you've used the previous chain for several hundred miles and not regularly cleaned it then that chain may have worn the cassette/chainrings away a fraction, which could make the difference to the new chain not getting along with 'used' parts?
  • Echoing the above comment - sounds like your cassette has been worn down by the old chain, and needs replacing. Regularly check your chains, and replace when they start to get stretched, otherwise you will have to replace your cassette each time you replace your chain.

    Make sure you regularly clean your drivechain to slow down chain wear.
  • jp1970
    jp1970 Posts: 134
    I'm not too sure how many miles the old chain had covered as the groupset was 2nd hand.

    But i'm still puzzled as to why the old chain is now slipping ??
  • owenlars
    owenlars Posts: 719
    http://sheldonbrown.com/chains.html

    This link to the cycle master's web site should reveal all. In particular look at the bit on chain and sprocket wear.
  • jp1970
    jp1970 Posts: 134
    thanks for the responses ...

    Owenlars - i did take a peek at the sheldon brown site this morning... it was very useful (as always).

    I think the best option will be to replace the cassette and ensure the new chain is 8 speed.

    I may have a final tinker to ensure non of the links are jammed / sticking ....
  • Bozman
    Bozman Posts: 2,518
    I've just had the same issue on my mates bike, his chain was completely ******, I've never seen anything like it(should've taken a pic) but anyway I swapped his chain for a kmc chain and he got slippage under pressure, swapped the cassette and it's still slipping under pressure. The chainrings look okay but.........
  • jp1970
    jp1970 Posts: 134
    Found the problem...... one of the chain links was slightly bent this was causing the pin to protrude out slightly. I have managed to replace with a quick link.. it seems to have fixed the problem.... having a bit of difficulty trying to complete a full test run in my suit also my I've forgotten to bolt my cleats to my work shoes :D ....

    otherwise it's going to be an extremely slow and gentle ride back home :(