Rear mech compatibility.

noodleman
noodleman Posts: 852
edited October 2012 in Workshop
Hi guys.
I'm looking to buy a dura ace rear mech for a 11-25 cassette and 39-53 double up front. Not sure what length mech I need. I have my eye on a short cage but don't want to take the plunge and buy the wrong one. Any advise would be much appreciated. Thanks.
argon 18 e116 2013 Vision Metron 80
Bianchi Oltre XR Sram Red E-tap, Fulcrum racing speed xlr
De Rosa SK pininfarina disc
S Works Tarmac e-tap 2017
Rose pro sl disc

Comments

  • sungod
    sungod Posts: 17,501
    short answer, a short cage will be fine

    long answer...

    if you go to http://techdocs.shimano.com it has the info for their components, go to the dura ace section, find the model you are interested in, and check the specification

    the figures you need to consider are the maximum sprocket size, and the capacity

    for the da 7900, it is specified for maximum sprocket up to 28t, and capacity up to 33t

    capacity is the sum of differences between largest and smallest rings/sprockets on the front and rear

    for your set-up, that's...
    53 - 39 -> 14
    25 - 11 -> 14
    ...a capacity of 28

    so you are ok on both max sprocket size and on capacity
    my bike - faster than god's and twice as shiny
  • noodleman
    noodleman Posts: 852
    Thanks sungod. Great reply.
    argon 18 e116 2013 Vision Metron 80
    Bianchi Oltre XR Sram Red E-tap, Fulcrum racing speed xlr
    De Rosa SK pininfarina disc
    S Works Tarmac e-tap 2017
    Rose pro sl disc

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