10-speed chain too short

birdie23
birdie23 Posts: 457
edited January 2014 in Workshop
I changed my chain for the first time myself last night. Following instructions in Zinn for the length, however it's now far too short.

It's a 105 chain, is it safe to lengthen using two rejoining pins?
2012 Cube Agree GTC

Comments

  • gozzy
    gozzy Posts: 640
    Get a couple of kmc quick links.

    For future reference, Shimano's rear mech techdocs show how to determine chain length.
  • keef66
    keef66 Posts: 13,123
    If you're using the snap-off 10 speed Shimano pins properly then yes, you can safely stick a few links back on.

    Are you saying the Zinn book has duff advice on chain sizing? Or is there a possibility you've cocked up?

    Are you really sure it's too short? Will it physically go into the big / big combo? I have mine as short as possible, and in the big / big combo as long as there's some curve in the chain as it goes through the rear mech and the mech doesn't foul the cassette then I'm happy.
  • birdie23
    birdie23 Posts: 457
    I think it was a combination of my naivety and a bit of confusion from the book. It offers a few options and the one it presented as the norm said not to use it with a cassette bigger than 27t. Since I've got a 12-28t I used the next method and balls it up.

    It's definitely short in my opinion. Big-big makes the mech look like `\
    2012 Cube Agree GTC
  • rolf_f
    rolf_f Posts: 16,015
    Of course, you could do what everyone else does and just cut the new chain to the same length as the old one*........ ;)

    *I dunno, folk today - not got the common sense they were born with!!
    Faster than a tent.......
  • birdie23
    birdie23 Posts: 457
    Rolf F wrote:
    Of course, you could do what everyone else does and just cut the new chain to the same length as the old one*........ ;)

    *I dunno, folk today - not got the common sense they were born with!!

    Annoyingly this is what I was going to do but I thought it might be useful to learn the method... :oops:
    2012 Cube Agree GTC
  • rolf_f
    rolf_f Posts: 16,015
    birdie23 wrote:
    Rolf F wrote:
    Of course, you could do what everyone else does and just cut the new chain to the same length as the old one*........ ;)

    *I dunno, folk today - not got the common sense they were born with!!

    Annoyingly this is what I was going to do but I thought it might be useful to learn the method... :oops:

    Don't make things complicated! These calculation methods are only really useful if you are building a new bike or if you change cassette or chainset to different ratios but even then I reckon it is better to start with what you've got and work it out relative to that. If you increase your cassette range by a couple of teeth then trying with a chain three pairs longer and then shortening from there is going to be pretty safe. Start by checking that it goes into big big comfortably and then drop to small small. If the chain isn't running back across itself in the rear mech then it's fine. There is some slack in that chances are, you could run a link or two longer or shorter than you currently use anyway so there's no need to get too scientific about it.
    Faster than a tent.......

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