Advertise on Bikeforums.net



User Tag List

Results 1 to 6 of 6
  1. #1
    Senior Member claude's Avatar
    Join Date
    Oct 2000
    Location
    Malta, Europe
    Posts
    59
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Hi,

    I keep getting this recurring problem where my chain keeps dropping onto the BB when shifting from the middle to the lower chainring. It only happens occasionaly (always on the toughest climbs though!).

    Adjusting the mech any further to the right causes me problems shifting to the ring in the first place.

    Any ideas ??

    B.T.W. I've set the height of the derailleur as well as its angle (parellel to the chainrings right?)

    Claude

  2. #2
    NOT a weight weenie Hunter's Avatar
    Join Date
    Dec 2000
    Posts
    1,762
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Claude,
    Well first off what shifters are you using? What model der. is it? A couple of things come to mind. One is the height of the cage over the front chainring. it should only be about 3 to 4 mm. If you say the limit screw is adjusted enough and it still throws it then you may want to check the middle ring to see if it is bent or the granny gear also. If you are riding a road bike the same applies but not with a granny gear unless you have a triple. If you rings are bent and you can remove them try to get them straight. If this does not work then something we did was to slightly bend the front inside part of the cage in toward the outer part of the cage. You can do this with a pair of neddle nose pliers or a small adjustable wrench. Another thing is to shift down to the granny or smaller ring before you get to the climb. This will assure you do not shift under stress. The next thing I would do and this may not solve it but it never hurts to do it is replace the cable and housing. Hope this helps.

  3. #3
    Ich bin ein Lowlander! toolfreak's Avatar
    Join Date
    Mar 2001
    Location
    Atlantic Ocean, France
    Posts
    583
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Claude,

    if your front derailleur is perfectly set and your chain still flips of, maybe this is a option.

    http://gvtc.com/~ngear/

    (its called jump stop?)

    Cheers,

    Mark b.
    Mark







    Dancevalley 2th of august 2003 -> JXL, Laidback luke, Sasha, John Digweed, Monica Krusse.....and on!

  4. #4
    Senior Member mike's Avatar
    Join Date
    Jul 2000
    Location
    Snowy midwest
    Posts
    5,392
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    One more thing to check, and this is almost too crazy to mention, is "is your BB possibly loose?"

    Grab a crank and give it a good pull and good shake. Does it wiggle at all? If yes, this could be giving enough play for the chain to bang against the front derailure and throw the chain off of the sprocket.
    Mike

  5. #5
    Senior Mem. & Trail Sage steve33's Avatar
    Join Date
    Dec 2000
    Location
    Asheville NC
    Posts
    130
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    After all the above mentioned fixes, your problem is probably trying to shift under to mush pressure.
    This will cause your chain to overthrow, try to shift down to low enough gear before you start putting heavy pressure on your chain.
    Steve33

  6. #6
    NOT a weight weenie Hunter's Avatar
    Join Date
    Dec 2000
    Posts
    1,762
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Yeah thanks for the agreement Pete.

Posting Permissions

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