How long should my chain be ?

Very much value you help and advice as I am a newbie to road bikes and I don't trust YouTube.
Bought a new bike on eBay recently.
Specialized Roubaix 2018 Sport.
It came with a single ring crankset. Sram Force 1 carbon chainset 40t,
Miche close ratio cassette 12-29t and a KMC X11EL 11 Speed Extra Light Chain
I have changed this back to a "normal" easier to ride bike as it once was.
I have fitted a Shimano 105 compact crank 34-50t and a Shimano 105 rear cassette. The 105 rear deraileur is long cage, I left that in place.
I have bought a new KMC X11EL 11 Speed Extra Light Chain and fitted that also straight from the box.
Before I fitted the new chain I noticed that the old chain on the old single ring setup was shorter, I counted 4 links shorter.
My question is ...... is there a way of working how long your chain needs to be? How long does my chain need to be for my new setup. Do I need to take links out of my brand new chain. I'm okay with doing this, I have a chain pin removal tool.
Many thanks in advance for you answers. I'm very keen to learn from your knowledge, cheers.




Comments

  • Sorry I should have mentioned the new Shimano 105 cassette is 11-32t
  • david37
    david37 Posts: 1,313
    edited August 2020
    use the big big plus 2 links method for ease. use a marker pen mark the cut at the appropriate place. check out the park tool tutorial.
  • de_sisti
    de_sisti Posts: 1,283
    Baileysim said:


    I have bought a new KMC X11EL 11 Speed Extra Light Chain

    Wasn't there some fitting instructions (stating how long the chain should be) included in the packaging?
  • davidof
    davidof Posts: 3,127
    david37 said:

    use the big big plus 2 links method for ease. use a marker pen mark the cut at the appropriate place.

    and always use a new hacksaw blade
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  • wongataa
    wongataa Posts: 1,001
    Baileysim said:


    My question is ...... is there a way of working how long your chain needs to be?

    Read the Shimano installation instructions for chains.
  • akh
    akh Posts: 206
    edited August 2020
    The Shimano website has detailed dealer manuals with instruction on how to size chains for both double and single chainrings (check out the GRX manuals for single rings).

    Easier to watch this video from Park Tool though as it's the same methodology Shimano recommend. Note the recommended length for double and single chainring set ups isn't the same.

    **edit - linked the wrong video :P**

    https://www.youtube.com/watch?v=O0YibMDWBAw
  • davidof said:

    david37 said:

    use the big big plus 2 links method for ease. use a marker pen mark the cut at the appropriate place.

    and always use a new hacksaw blade
    Nice