Compact cranks and derailleur question

Discussion in 'Cycling Equipment' started by Sheldon Brown, Aug 3, 2004.

  1. Doug Taylor wrote:

    > The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
    > The specs for both Ultegra and Dura Ace front derailleurs show a
    > capacity to shift 15. The standard 130mm bcd 53-39 span is 14.
    >
    > So, will the Shimano derailleurs make the extra tooth jump? If so,
    > will shifting up be sluggish? If so, why not sell the compact with
    > 50-36? Or 35?


    It will work fine. See: http://sheldonbrown.com/capacity

    Sheldon "Eff Ay Cue" Brown
    +---------------------------------------------------------+
    | We are satisfied that there can be but little liberty |
    | on earth while men worship a tyrant in heaven. |
    | -- Robert Green Ingersoll |
    +---------------------------------------------------------+
    Harris Cyclery, West Newton, Massachusetts
    Phone 617-244-9772 FAX 617-244-1041
    http://harriscyclery.com
    Hard-to-find parts shipped Worldwide
    http://captainbike.com http://sheldonbrown.com
     
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  2. Doug Taylor

    Doug Taylor Guest

    The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
    The specs for both Ultegra and Dura Ace front derailleurs show a
    capacity to shift 15. The standard 130mm bcd 53-39 span is 14.

    So, will the Shimano derailleurs make the extra tooth jump? If so,
    will shifting up be sluggish? If so, why not sell the compact with
    50-36? Or 35?

    --dt
     
  3. Doug Taylor

    Doug Taylor Guest

    Sheldon Brown <[email protected]> wrote:

    >Doug Taylor wrote:
    >
    >> The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
    >> The specs for both Ultegra and Dura Ace front derailleurs show a
    >> capacity to shift 15. The standard 130mm bcd 53-39 span is 14.
    >>
    >> So, will the Shimano derailleurs make the extra tooth jump? If so,
    >> will shifting up be sluggish? If so, why not sell the compact with
    >> 50-36? Or 35?

    >
    >It will work fine. See: http://sheldonbrown.com/capacity


    Thanks, Sheldon. I actually searched through your glossary prior to
    my post, but didn't think to look under "capacity." Doh!

    --dt
     
  4. psycholist

    psycholist Guest

    "Doug Taylor" <[email protected]> wrote in message
    news:[email protected]
    > Sheldon Brown <[email protected]> wrote:
    >
    > >Doug Taylor wrote:
    > >
    > >> The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
    > >> The specs for both Ultegra and Dura Ace front derailleurs show a
    > >> capacity to shift 15. The standard 130mm bcd 53-39 span is 14.
    > >>
    > >> So, will the Shimano derailleurs make the extra tooth jump? If so,
    > >> will shifting up be sluggish? If so, why not sell the compact with
    > >> 50-36? Or 35?

    > >
    > >It will work fine. See: http://sheldonbrown.com/capacity

    >
    > Thanks, Sheldon. I actually searched through your glossary prior to
    > my post, but didn't think to look under "capacity." Doh!
    >
    > --dt


    It's working fine for me. I'm riding DA with FSA compact. Setup on my Trek
    5500 isn't ideal. In fact, I didn't think it was going to work. But it
    works just fine. I've never dropped a chain or noted any sluggishness in
    the shifting whatsoever. And the stiffness of the crank is quite
    noticeable. I really like it.

    Bob C.
     
  5. On Tue, 03 Aug 2004 11:56:52 -0400, Doug Taylor wrote:

    > The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
    > The specs for both Ultegra and Dura Ace front derailleurs show a
    > capacity to shift 15. The standard 130mm bcd 53-39 span is 14.
    >
    > So, will the Shimano derailleurs make the extra tooth jump?


    No problem, though adjustment might need to be more precise.

    > If so,
    > will shifting up be sluggish?


    No

    > If so, why not sell the compact with
    > 50-36? Or 35?


    People going for this are looking for lower gears.

    BTW, I use a 46/30, also 16 teeth, with a Campy front derailleur. No
    problems at all. I did get a chain watcher, since when I put on the
    granny (22 teeth), it did miss a few downshifts. I leave granny at home
    unless I'm touring, but leave the chain watcher on. Probably a good idea
    with a wide range front double.

    --

    David L. Johnson

    __o | When you are up to your ass in alligators, it's hard to remember
    _`\(,_ | that your initial objective was to drain the swamp. -- LBJ
    (_)/ (_) |
     
  6. taylor-<< The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
    The specs for both Ultegra and Dura Ace front derailleurs show a
    capacity to shift 15. The standard 130mm bcd 53-39 span is 14. >><BR><BR>

    The shimano or Campagnolo front ders for double will work fine with the
    compact. We have done it many times.

    Peter Chisholm
    Vecchio's Bicicletteria
    1833 Pearl St.
    Boulder, CO, 80302
    (303)440-3535
    http://www.vecchios.com
    "Ruote convenzionali costruite eccezionalmente bene"
     
  7. Doug Taylor wrote:
    > So, will the Shimano derailleurs make the extra tooth jump? If so,
    > will shifting up be sluggish? If so, why not sell the compact with
    > 50-36? Or 35?


    Others have answered that it will work fine (and they are correct).
    I'm currently using an old Shimano 600 double front deraileur with
    a triple crank and a 20T difference between big and small. I'm sure
    it wasn't meant for that much. It's been no problem.

    As to why they don't offer more sizes, I assume that's a sales
    decision based upon what they think most customers will want and
    how much it will cost them to supply more sizes.

    It's easy enough to buy a bigger chain ring if you want one. 110's
    are not too difficult to find in many sizes.

    Another problem might be rear deraileur capacity. You might want
    to look into a medium or long cage rear deraileur to handle your
    larger range of gearing. A normal road deraileur meant for a normal
    double may be fine if you have a minimal range rear cluster but if
    you've got a lot of range in the back too, you're going to need to
    take up more chain slack or not have enough chain to use the larger
    few cogs in the back with the large ring in the front. For example,
    if you have an 11-27 in the back, that's 16T + 16T on the front
    for 32T. The Ultegra rear deraileur for double is rated for 29T
    total capacity and the triple is rated for 37T total capacity. 32T
    may be close enough; especially since big-big is probably not a good
    gear to be in but if you go much wider, it could be a problem
    without the long cage rear deraileur.

    BTW, I'm using a regular short rear deraileur with my 13-26 in the
    back and it *is* a problem. I've got way too much slack on the
    small-small combination so I don't go near it. There isn't enough
    chain for big-big so I can't do that either. I probably wouldn't
    use those extremes anyway but I really don't even have the choice.
     
  8. Doug Taylor <[email protected]> wrote in message news:<[email protected]>...
    > The FSA compact crank comes with 50-34 tooth rings - a 16 tooth span.
    > The specs for both Ultegra and Dura Ace front derailleurs show a
    > capacity to shift 15. The standard 130mm bcd 53-39 span is 14.
    >
    > So, will the Shimano derailleurs make the extra tooth jump? If so,
    > will shifting up be sluggish? If so, why not sell the compact with
    > 50-36? Or 35?
    >
    > --dt


    I changed to FSA compact cranks on my DA equipped Merlin and it works
    just fine. No shifting problems at all. I got the cranks for my trip
    to the French Alps this summer and I was very happy to have the
    compact cranks. They made up for my lack of training and advancing
    age. Oh, they look cool too and are very stiff and light. I like the
    cranks so much that now that I'm back, I have not switched back to the
    DA cranks.

    I find that I shift between the big ring and little ring more with the
    50-34 than I did with the 53-39, so it's a good thing that front
    shifting is just fine.
     
  9. Paul Kopit

    Paul Kopit Guest

    I've found that if the big ring has good shift assists, that either
    Campy or Shimano front derailleurs work fine. I regularly use SR
    chainring and also Shimano HG. The shift assists are zero to minimal.
    The Campy front derailleur is a clear winner.

    I have not had to use longer cage rear derailleurs on my bikes or my
    wife's. With 50/34 and a standard cage rear derailleur, I can shift
    13/29 and cross chain either way. A bicycle with longer chainstays
    would do better with medium cage derailleur. I needed to use a long
    cage rear derailleur on a single touring bicycle that had 50/36 x
    12/32. I needed 2 full links longer than I use on my Cannondale CAADx
    bikes.
     
  10. Doug Taylor

    Doug Taylor Guest

    [email protected] (Eagle Jackson) wrote:

    >I changed to FSA compact cranks on my DA equipped Merlin and it works
    >just fine. No shifting problems at all. I got the cranks for my trip
    >to the French Alps this summer and I was very happy to have the
    >compact cranks. They made up for my lack of training and advancing
    >age. Oh, they look cool too and are very stiff and light. I like the
    >cranks so much that now that I'm back, I have not switched back to the
    >DA cranks.
    >
    >I find that I shift between the big ring and little ring more with the
    >50-34 than I did with the 53-39, so it's a good thing that front
    >shifting is just fine.


    What cassette do you use?
    --dt
     
  11. Doug Taylor <[email protected]> wrote in message is just fine.
    >
    > What cassette do you use?
    > --dt


    I use both a 12-25 and a 13-27. I put the 13-27 on while in Europe
    for the ride up Alpe d'Huez. I also have a 12-23 that I will also use
    but haven't yet tried with the compact crank.

    The bike is a 55cm Merlin Extralight with 9sp DA.

    My wife has a Spectrum with Campy Record 10s. She put an FSA compact
    crank on her bike too for the trip and loves it. She rides a 13-26
    and 13-29. Actually, first she put a triple on and didn't like it at
    all. She saw how much I liked my compact crank so she switched to one
    too, and loved it.
     
  12. Doug Taylor

    Doug Taylor Guest

    [email protected] (Eagle Jackson) wrote:

    >> What cassette do you use?
    >> --dt

    >
    >I use both a 12-25 and a 13-27. I put the 13-27 on while in Europe
    >for the ride up Alpe d'Huez. I also have a 12-23 that I will also use
    >but haven't yet tried with the compact crank.


    Thanks. I ask because of other posts questioning whether a normal
    cage derailleur and the chain will handle the gearing with compact
    front rings and big teeth cassettes.

    Once I get my cranks, I'm thinking of switching the 34 tooth small
    ring with a 36, taking a link out of the chain I'm running with the
    53-39, and staying with my 12-26 cassette. If that's not low enough
    for big grades, I'll see how the 34 works.

    Checking out gear ratio charts, I notice that running a 11-23 cassette
    puts me close to where I was with the standard front rings and the
    12-26 cassette for riding tamer terrain.

    --dt
     
  13. Paul Kopit

    Paul Kopit Guest

    On Fri, 06 Aug 2004 16:17:21 -0400, Doug Taylor
    <[email protected]> wrote:

    >Once I get my cranks, I'm thinking of switching the 34 tooth small
    >ring with a 36, taking a link out of the chain I'm running with the
    >53-39, and staying with my 12-26 cassette. If that's not low enough
    >for big grades, I'll see how the 34 works.


    Actually, you'd be better off with 48/34 with the 12/26. Keep the
    50/34.
     
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