Results 1 to 18 of 18
  1. #1
    mtbr member
    Reputation:
    Join Date
    Dec 2010
    Posts
    42

    Gears skipping on descent?

    All,

    I am having problems with my gears skipping while I am descending.

    Here is the background:

    I ride an Ibis Mojo SL with a 140mm X-fusion shock, 1x10 set-up, MRP chainguide and tensioner, SRAM XO med cage derailleur, SRAM 10spd chain and shifter.

    I live in Arizona and the terrain is super chunky. I find that when I descend at speed (25mph+) and go to pedal for more speed, my gears skip. Any ideas?

  2. #2
    mtbr member
    Reputation: nauc's Avatar
    Join Date
    Sep 2009
    Posts
    1,210
    skip, like broken freehub? or changes gears
    2010 GT Avalanche Expert

  3. #3
    mtbr member
    Reputation:
    Join Date
    Dec 2010
    Posts
    42
    Changes gears. Its kind of exciting but not the good kind of exciting.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Apr 2012
    Posts
    11
    It's possible that you have a small amount of play in your hub or pivot bearings and under the right forces the angle of the hub/cassette changes just enough to cause the chain to slip to the next ring.

  5. #5
    Elitest thrill junkie
    Reputation: Jayem's Avatar
    Join Date
    Jul 2005
    Posts
    18,505
    Cable routing/cable too short. Those are often the culprits for ghost-shifting.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  6. #6
    Let the good times roll.
    Reputation: miniwisejosh's Avatar
    Join Date
    Sep 2007
    Posts
    1,156
    Exactly which gears are skipping? Is the chain dropping from the 2nd smallest gear to the smallest gear when you hit bumps?

  7. #7
    mtbr member
    Reputation:
    Join Date
    Dec 2010
    Posts
    42
    Its funny you mention this, I have been hearing some squeaking recently from the near the pivots. I am going to tear my bike apart on Wed. I let you know what I find.

  8. #8
    mtbr member
    Reputation:
    Join Date
    Dec 2010
    Posts
    42
    Yes, jumping between the smallest and second smallest. Truth be told, I am guessing at this one as I am looking forward at that speed vs. at the gears. However, I am in the smallest gear when it happens. I dont think it is the cabling/ routing as I have a little extra slack in the line but I will check that as well.

  9. #9
    Let the good times roll.
    Reputation: miniwisejosh's Avatar
    Join Date
    Sep 2007
    Posts
    1,156
    I recommend double checking the limit screw and chain length. I think a too-loose chain or too-tight limit screw would cause what you are describing.

  10. #10
    mtbr member
    Reputation:
    Join Date
    Jan 2004
    Posts
    5,653
    Quote Originally Posted by btablak View Post
    Yes, jumping between the smallest and second smallest. Truth be told, I am guessing at this one as I am looking forward at that speed vs. at the gears. However, I am in the smallest gear when it happens. I dont think it is the cabling/ routing as I have a little extra slack in the line but I will check that as well.
    Do the highest gears shift ok on the work stand?

  11. #11
    mtbr member
    Reputation: Snfoilhat's Avatar
    Join Date
    May 2010
    Posts
    433
    The guide (upper) pulley is pretty far away from the smallest cogs in a wide (like 11-36T) cassette, and so little problems might be exaggerated. It shifts perfectly under load on a smooth road sprint, same speed, same gears?

    A medium-cage derailleur doesn't offer quite the tension a short cage would, but of course a lot of 1xs are made out of the stock 2x parts cause giving up a $$$$ RD and buying a new one is impractical.

    1) slightly bent derailleur hanger + imperfect high limit (these often go together)
    2) pedaling hard into chunk over 25 mph. Slow down?

  12. #12
    mtbr member
    Reputation: felimen's Avatar
    Join Date
    Jun 2010
    Posts
    39

    Gears skipping on descent?

    I say hanger is bent . It don't take much. Put the bike in stand drop the chain into smallest gear stand in back of the bike and pedal while looking between the chain/gear and hanger , shine a light from under if needed and see if the gap stays the same . If it looks fine , try turning your adjuster barrel. Good luck


    Sent from my iPhone using Tapatalk

  13. #13
    mtbr member
    Reputation: wilsonblur's Avatar
    Join Date
    Dec 2003
    Posts
    1,104
    Quote Originally Posted by btablak View Post
    Yes, jumping between the smallest and second smallest. Truth be told, I am guessing at this one as I am looking forward at that speed vs. at the gears. However, I am in the smallest gear when it happens. I dont think it is the cabling/ routing as I have a little extra slack in the line but I will check that as well.
    Check everything the other posters mention and take a look at your chain wear and cassette wear as well. I had a worn cassette that would jump from the second smallest to the smallest under power when going down hill. The chain would slip out of the teeth on the second smallest gear and the tension of the derailleur would pull it down to the first. It would also slip in the smallest cog too. The smallest cogs don't have as many teeth in the chain as the bigger ones do and will be one of the first places that lets you know your cassette is worn. Hope its something easier and less expensive than this.
    Narrow is the path to life, few are those who find it.

  14. #14
    mtbr member
    Reputation:
    Join Date
    May 2007
    Posts
    161
    Check your b screw on the rear derailleur. It could be too far away from the cassette.

  15. #15
    squish, squish in da fish
    Reputation: fishwrinkle's Avatar
    Join Date
    Jul 2012
    Posts
    865
    ^^^ i bet ya thats it.

  16. #16
    mtbr member
    Reputation:
    Join Date
    Dec 2010
    Posts
    42
    Quick Update - I checked the hanger and it was not bent. Good news. I also checked the chain, cog, and chain ring for wear and they all looked good. Again, Good news. I checked the rear triangle - and it was loose. Not too bad but enough. I tightened it up and have *less* skipping. I am working on the bike this weekend and will check the b-screw. Thank you all for the ideas!

  17. #17
    mtbr member
    Reputation: Gman086's Avatar
    Join Date
    Jul 2004
    Posts
    3,313
    3rd on the b-tension being to tight as that won't wrap as much chain around the smaller cogs and chain can skip to the smallest cog!

    Have FUN!

    G MAN
    "There's two shuttles, one to the top and one to the hospital" I LOVE this place!!!

  18. #18
    mtbr member
    Reputation: Fuglio's Avatar
    Join Date
    Jul 2011
    Posts
    2,479
    its a shitty tune job on a bike that loves to throw chains

Similar Threads

  1. Skipping gears one way, perfect the other, going crazy.. (VIDEO ADDED)
    By ja001son in forum Drivetrain - shifters, derailleurs, cranks
    Replies: 29
    Last Post: 11-17-2013, 11:58 PM
  2. Skipping chain on high gears
    By tsjwdf in forum Drivetrain - shifters, derailleurs, cranks
    Replies: 7
    Last Post: 06-28-2013, 05:00 AM
  3. Trance x4 skipping gears
    By kevingp in forum Drivetrain - shifters, derailleurs, cranks
    Replies: 0
    Last Post: 03-25-2012, 08:09 AM
  4. Gears skipping
    By LSmith4285 in forum Drivetrain - shifters, derailleurs, cranks
    Replies: 10
    Last Post: 11-24-2011, 04:57 AM
  5. 2x9 setup, chain rubbing on tyre, skipping gears
    By nuclear_powered in forum Drivetrain - shifters, derailleurs, cranks
    Replies: 6
    Last Post: 01-13-2011, 02:34 PM

Posting Permissions

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