compact chainset to 53/39 - longer chain required?

page23 Posts: 182
edited October 2009 in Workshop
hi all,

i've just ordered a shimano 105 double 53/39 chainset to replace a compact 105 double chainset. it occured to me that as a result i may need a longer chain. would anyone care to let me know if this is the case or whether i can get away with what i already have on the bike?



  • balthazar
    balthazar Posts: 1,565
    Shift the gears to largest rear sprocket/small chainring (lowest gear) then try lifting the chain by hand onto the big chainring, then gently shift the front mech to match. Turn the pedals slowly, and if everything works and the rear mech still has some spring left, then it's ok. If it doesn't work and binds, then you need to add a link.

    *Don't do this by spinning the wheels and shifting on a stand, because even on a stand the mech as at risk of being bent if the chain is too short. Do it by hand as I described.
  • John.T
    John.T Posts: 3,698
    To get the rear mech back to the same place you would need 1.5 links adding (3 teeth). Check as Balthazar says but if in any doubt at all you need a longer chain.
    You could have saved some money by getting new chain rings to fit your compact cranks. Stronglight and TA both do them.
  • page23
    page23 Posts: 182
    i could have, but i was also after shorter crank arms.