Cassette change, will i need a longer chain

garyk72
garyk72 Posts: 76
edited March 2015 in Workshop
My cassette and chain have become worn and I have bought a new cassette and chain to fit to the bike. Cassette and chain are Shimano Ultegra 10 speed.

My question is this.... My current cassette is 11-25 and the new one is 11-28. Do you think I will need to cut the new chain a link or two longer then the old one due to the larger 28 sprocket on the new cassette?

Cheers
G

Comments

  • Smokin Joe
    Smokin Joe Posts: 2,706
    http://www.epicidiot.com/sports/chain_l ... ulator.htm
  • dj58
    dj58 Posts: 2,223
    Download a copy of the General Operations manual, DM-GN0001-10-ENG.pdf from here http://si.shimano.com/ go to page 16 for road rear derailleur chain length recommendtions.
  • HertsG
    HertsG Posts: 129
    You can't do one link longer. Two links longer should be fine.
  • keef66
    keef66 Posts: 13,123
    HertsG wrote:
    You can't do one link longer. Two links longer should be fine.

    In conventional chain terminology one link is an inch long and consists of a pair of inner plates and a pair of outer plates, so you can increase / decrease chain length by one link.

    Confusingly some people and even some manufacturers now use the term link to mean half this length.

    I usually follow the Shimano advice: for a double chainset wrap the chain round the biggest chainring and biggest sprocket but not through the rear mech then add one link (inch)

    For a triple it's biggest chainring, smallest sprocket, through the rear mech, and adjust chain length so the jockey wheels are vertically aligned.
  • arlowood
    arlowood Posts: 2,561
    Using the calculator in Smokin Joe's post indicates that the same chain length will do for either cassette option.

    I'd just measure the new chain as per the results from the calculator rather than assume that the old chain was originally cut to the ideal length.
  • garyk72
    garyk72 Posts: 76
    Thanks for the replies guys, I have been informed by my LBS that my current chain is too long so I will be using the calculator recommended by Smokin' Joe when I install the new chain and cassette this weekend.

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