Chain length

jockyfoost
jockyfoost Posts: 63
edited January 2009 in Workshop
I need to replace the rear mech on my bike as old one is badly bent. I have a triple chainset with a long cage rear. If i replace it with a new mech with a medium cage will i need to shorten the chain?

Comments

  • John.T
    John.T Posts: 3,698
    Will the medium cage mech cover the range of your triple. If not the question is irelevent. If it will then you should shorten the chain. You should have the jockey wheels vertical with the chain on big ring and small cog.
  • it is a medium cage triple rear mech i'm looking at getting. Thanks for your help.
  • The rear mech you need depends on the gearing you have, and what make. Is it Shimano, Campagnolo or SRAM? Ribble have a useful rear mech selection guide here. As for chain length, I'm not sure, but I've once read somehwere that the ideal chain length can be determined by taking the chain round the large sproket to the large chainring, missing out the rear mech, plus 2 links. I'm not sure if this works for triples, however.
    "There's a way of transferring funds that is even faster than electronic banking. It's called marriage."
    James Holt McGavran
  • John.T
    John.T Posts: 3,698
    Jocky. The mech you need is dictated by the max range of teeth between the big/big and small/small combinations, not by which one you would like to use. If this is within the range for a medium mech then by all means go for it. You can then shorten the chain as said. Both the method I described and Slowhands work. Check Parktools for others.
  • giant_man
    giant_man Posts: 6,878
  • Thanks John.T. Going by that link i think i may have ordered the right one for my Shimano set up. I have a 12*27 Triple. Just have to see.