New Chain

mabbo Posts: 117
edited May 2012 in Workshop
I have a 105 chain and cassette on my Giant Defy1, 2010. Had the bike since March 2010. Completed 5000 miles.
The gears work fine, no noise, no issues. So why do I read here and there that a chain needs to be changed after a couple of 000's miles?
How do I tell if the chain is worn? My old bike is a Giant with Shimano kit,( Bio-Pace it was called), and I have never replaced the chain or cassette. The gears still work fine, and it still pedals well in the winter months. I cannot even guess how many miles it may have done, but certainly over 10,000.
So my question is when does a chain need to be replaced? I am not a member of any racing team, so do normal commuting, fun rides at weekends and in the summer with mates. I always manage at least 60 miles a week, rain or shine, in summer over 150 a week. Plenty of hills.
So what am I missing with my old 5000 + miles chain that a new chain would give me?

If I do do I get the chain off? Do new chains come with split pins, like the old days? Or is it all specialist tools required now?


  • schlepcycling
    schlepcycling Posts: 1,614
    Chains don't need to be changed after x miles, they need to be changed when they're worn and many factors can influence how fast chain wears. The reason you change a chain before it becomes worn because a worn chain will wear the chainrings and cassette sprockets so when you do come to change the chain it will skip on the now worn chainrings and cassette which will be much more expensive to replace. A chain is classed as worn when it has stretched beyond a certain limit and you can either use a chain checker like this or you can measure the stretch using a ruler. Lots of interesting chain reading here

    As for new chains some notably KMC come with reuseable connecting links allow no tool splitting and rejoinging of the chain, these 'links' can also be used on other brands of chains (I use KMC links on all my chains).

    To remove an old chain you just need a chain tool like this which will allow you to split the old chain so you can get it off.
    'Hello to Jason Isaacs'
  • sungod
    sungod Posts: 16,860
    good advice above

    imho if you've done 5000 miles on that chain, chances are that it has worn enough to mean the cassette will wear or skip with a new chain - if you measure the chain you'll be able to see how far it has worn, it's simple to do with a ruler (see the sheldon brown link)

    if it's badly worn, you are better off riding it a few more months, then change chain and cassette together
    my bike - faster than god's and twice as shiny