Advertise on Bikeforums.net



User Tag List

Results 1 to 11 of 11
  1. #1
    Junior Member
    Join Date
    Jan 2002
    Location
    Stephens City, VA
    Posts
    6
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Cross Chaining and shifting

    I recently upgraded my Shimano 7speed (13-23) setup to 9 speed (12-23). I purchased the 9 speed upgrade with a new wheelset, but retained my older Shimano FD-6401 front deraileur. I have been unable to adjust the front deraileur to eliminate throwing the chain off occasionally when shifting from the large chainring (53T) to my small chainring (39T). I decided to replace the front deraileur with the new FD-6500 which is easier to adjust, but occassionally it will still drop the chain. It is more prevalent when shifting from the 53X21 or 23 down to the 39T chainring. Should I avoid shifting when the chain is crossed over that far??

    I am still using the 6400 series crank arms with the 9 speed chainrings and 9 speed chain...any thougths???

  2. #2
    Just ride. roadbuzz's Avatar
    Join Date
    Oct 2000
    Location
    C-ville, Va
    Posts
    3,237
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Originally posted by serottalt
    Should I avoid shifting when the chain is crossed over that far??
    Definitely! Here's an approximate gear-inch table for your setup:

    Wheel Diameter: 24.50 inches
    Gears: 39/53 12-13-14-15-16-17-19-21-23
    -----------------------------------
    SP CRxFW GI diff
    -----------------------------------
    1> 39x23 41.54 12.43
    2> 39x21 45.50 15.05
    3> 39x19 50.29 18.59
    4> 39x17 56.21 0.79
    5> 53x23 56.46 10.25
    6> 39x16 59.72 6.64
    7> 53x21 61.83 5.86
    8> 39x15 63.70 14.29
    9> 39x14 68.25 0.29
    10> 53x19 68.34 16.20
    11> 39x13 73.50 9.06
    12> 53x17 76.38 10.19
    13> 39x12 79.62 4.81
    14> 53x16 81.16 17.00
    15> 53x15 86.57 19.43
    16> 53x14 92.75 22.41
    17> 53x13 99.88 26.15
    18> 53x12 108.21 0.00
    -----------------------------
    SP CRxFW GI diff
    -----------------------------

    You can get pretty close to the same ratios on your 39, if you just practice and get used to shifting over sooner! In addition to throwing the chain less, you'll get smoother shifts and less wear and tear on equipment.

  3. #3
    Junior Member
    Join Date
    Jan 2002
    Location
    Stephens City, VA
    Posts
    6
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Thanks roadbuzz! I just finished charting the gear inches before I got your reply...makes good sense! When I purchased the upgrade (Shimano Ultegra) I got alot of different advice about what I needed from LBS's upto new BB and cranks. Seemed a bit excessive to me, but the new front derailleur made the difference. Guess I wan't used to a wheel dished that far making such a difference when shifting in the front. Now I will just have to ride and practice shifting until the pattern becomes automatic. Winter weather today...4-8 inches of snow so it's trainer time. Thanks again for the info...

    Keith

  4. #4
    Banned
    Join Date
    Aug 2001
    Location
    upstate New York
    Posts
    1,688
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    With a 9-speed rear, you should never be in the 2 biggest cogs when you are on the big ring, or in the 2 smallest cogs on the small ring.
    Je vais à vélo, donc je suis!

  5. #5
    Just ride. roadbuzz's Avatar
    Join Date
    Oct 2000
    Location
    C-ville, Va
    Posts
    3,237
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    If you're new to STI (coming from downtube shifters), you'll find that you'll use your gears more, shifting more often. So dropping to the smaller chainring sooner is just a matter of changing existing habits.

    P.S. I was just commiserating (sp?) about your comment on the weather when I noticed we're neighbors. Well, almost. Do you ride any of the centuries in the area? I usually ride at least one of the centuries put on by the SVBC (Harrisonburg) each year.
    Last edited by roadbuzz; 01-20-02 at 06:44 PM.

  6. #6
    Mr. Cellophane RainmanP's Avatar
    Join Date
    Nov 2000
    Location
    New Orleans, LA
    Posts
    3,037
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Perhaps I am naive or just lucky, but it seems to me you should never be dropping your chain except in very unusual circumstances. Are you sure you have your low limit properly adjusted?
    If it ain't broke, mess with it anyway!

  7. #7
    Senior Member
    Join Date
    Feb 2002
    Posts
    813
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Did you also install an 8/9 speed front derailleur? The inner cage plate has a contour that was designed to prevent chain dropping on front downshifts. Shimano didn't introduce this with the original 8-speed group--they realized that a change was needed when your problem showed up on most bikes equipped with that group.

  8. #8
    feros ferio John E's Avatar
    Join Date
    Jul 2000
    Location
    www.ci.encinitas.ca.us
    My Bikes
    1959 Capo; 1980 Peugeot PKN-10; 1981 Bianchi; 1988 Schwinn KOM-10;
    Posts
    14,784
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    Part of the problem may be the indexing of the STI shifter. With friction shift (the only way to go on the front derailleur control, as Campy still realizes), one can control the motion of the cage and guide the chain to avoid overshifting. Also, being able to fine-tune the position of the front cage allows a narrower cage to be used, which also reduces the chance of overshifting.
    "Early to bed, early to rise. Work like hell, and advertise." -- George Stahlman
    Capo [dschaw'-poe]: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger, S/N 42624
    Peugeot: 1970 UO-8, S/N 0010468
    Bianchi: 1981 Campione d'Italia, S/N 1.M9914
    Schwinn: 1988 Project KOM-10, S/N F804069

  9. #9
    Donating member Richard D's Avatar
    Join Date
    Sep 2001
    Location
    Faversham, Kent, UK
    Posts
    1,852
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Gripshifters normally allow fine adjustment of the front derailleur - the indexed position is marked but you can click it in intermediate positions.

    Richard
    Currently riding an MTB with a split personality - commuting, touring, riding for the sake of riding, on or off road :)

  10. #10
    The Flying Scot chewa's Avatar
    Join Date
    Aug 2001
    Location
    North Queensferry Scotland and London (and France)
    My Bikes
    Custom 531c fast tourer/audax, 1964 Flying Scot Continental, 1995 Cinelli Supercorsa, Holdsworth Mistral single speed, Dahon Speed 6 (folder), Micmo Sirocco
    Posts
    1,811
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Originally posted by John E
    Part of the problem may be the indexing of the STI shifter. With friction shift (the only way to go on the front derailleur control, as Campy still realizes), one can control the motion of the cage and guide the chain to avoid overshifting. Also, being able to fine-tune the position of the front cage allows a narrower cage to be used, which also reduces the chance of overshifting.
    Hurrah for friction shifters.

    I use Campag downtube levers on my main bike and never have trouble shifting or adjusting the chain run (they activate a campag front mech and a Huret duopar long cage rear), but on my other bike the front is friction, the rear is indexed (both Shimano and both mechs too), but I can't get used to the indexing.

    I'm going to swap to Campag levers as soon as I can find some mid 60's ones. (the bike was built in '63)
    plus je vois les hommes, plus j'admire les chiens

    1985 Custom built 531c Audax/fast tourer.
    1964 Flying Scot Continental
    1995 Cinelli Supercorsa
    1980s Holdsworth Mistral fixed
    2005 Dahon Speed 6 (folder)
    (YES I LIKE STEEL)
    2008 Viking Saratoga tandem
    2008 Micmo Sirocco Hybrid (aluminium!)
    2012 BTwin Rockrider 8.1

  11. #11
    feros ferio John E's Avatar
    Join Date
    Jul 2000
    Location
    www.ci.encinitas.ca.us
    My Bikes
    1959 Capo; 1980 Peugeot PKN-10; 1981 Bianchi; 1988 Schwinn KOM-10;
    Posts
    14,784
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    Originally posted by chewa
    I'm going to swap to Campag levers as soon as I can find some mid 60's ones. (the bike was built in '63)
    I am still using the original 1959 and 1982 Campy downtube shifters on my Capo and my Bianchi. They weigh next to nothing, operate reliably and smoothly, look classy, and definitely stand the test of time.

    For both-hands-on-the-bars scenarios, I like SunTour ratchet barcons, and I just bought a set for one of the Peugeots.
    "Early to bed, early to rise. Work like hell, and advertise." -- George Stahlman
    Capo [dschaw'-poe]: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger, S/N 42624
    Peugeot: 1970 UO-8, S/N 0010468
    Bianchi: 1981 Campione d'Italia, S/N 1.M9914
    Schwinn: 1988 Project KOM-10, S/N F804069

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •