Results 1 to 8 of 8
  1. #1
    I should be studying...
    Reputation: frank daleview's Avatar
    Join Date
    Jan 2004
    Posts
    834

    Wierd Vibration coming from drive train

    I recently installed a new set of Cranks (Shimano FCR700 compact road cranks), a new cassette (shimano ultegra 9 12-25), and a new chain (sram 991 hollow pin) on my Cannondale road bike. I noticed a vibration during hard efforts in the big ring during the 2-5 o'clock positions on the crank. I know this an mtb forum, but I know a lot of you also ride road bikes, and the people on the road forum seem a little less technically oriented.

    As far as I can tell there is no play in the cranks or cassette.

    Any help would be sincerely appreciated!
    Formerly known as iceaxe

  2. #2
    mtbr member
    Reputation:
    Join Date
    Nov 2008
    Posts
    1,496
    We're talking high frequency vibration here, not a few creaks or clicks, right?

    Give it a chance to break in. Imperceptable flaws on the cassette cogs need to be worn off. After a few miles the chain and cassette will wear together to a perfect match, and it should run smoother. Your choice of chain lubes might also be a factor.
    fb
    www.chain-L.com

    The key to solving any problem is to understand and address the underlying cause.

  3. #3
    I should be studying...
    Reputation: frank daleview's Avatar
    Join Date
    Jan 2004
    Posts
    834
    Yeah I see you saw my X-post from RBR. Yeah it's a medium to high frequency vibration, it's just really pronounced in the crank arms during strong efforts. There is absolutely no perceptible play in the cassette/freehub interface, nor in the bottom bracket crank interface. It's definitely not a click or creak. I hope you are right about the components wearing together.
    Formerly known as iceaxe

  4. #4
    mtbr member
    Reputation: cort's Avatar
    Join Date
    Mar 2004
    Posts
    892
    I noticed a vibration during hard efforts in the big ring during the 2-5 o'clock positions on the crank

    Hmm hard to tell without riding the bike, but this seems to be occurring at your power stroke point. I wounder if you are deflecting the crank arm a bit. Any chance you are a big lad? And does this happen only at the extreme ends of the cassette range?

    I would check your limit screw adjustments and see if they need to be "tweaked" a bit for your new set-up (do you use or have a trim feature set-up?)

  5. #5
    mtbr member
    Reputation:
    Join Date
    Nov 2008
    Posts
    1,496
    Cort's advice is spot on. Crank and/or frame deflection can cause the chain to rub the front derailleur cage, usually in the highest gear or gears, since the deflection will be towards the outside. Check trim and/or adjust the outer limit slightly.

    I omited this advice earlier, since I assumed an experienced rider would recognize the sound and feel of an out of trim FD.
    fb
    www.chain-L.com

    The key to solving any problem is to understand and address the underlying cause.

  6. #6
    I should be studying...
    Reputation: frank daleview's Avatar
    Join Date
    Jan 2004
    Posts
    834
    I'm not a big guy (5'10" & 155 lbs.) and I am certain it's not the FD--I'm a very experienced mechanic. It's is most definitely happening during the time of maximum force application to the pedals. I agree with FB, the drive train components probably need to wear together a bit. Keep in mind that the crank is designed for 10 speed and I am using a 9 peed chain, cassette etc. I also feel the chain line is off a bit, but to my knowledge, there is no way adjust the shimano crank. I'll ride it for a while and see if it improves. Thanks for the insights!
    Formerly known as iceaxe

  7. #7
    mtbr member
    Reputation: D.F.L.'s Avatar
    Join Date
    Jan 2004
    Posts
    1,770
    What you're describing sounds like the vibration you feel through your feet, but don't really hear. It feels like the drivetrain isn't meshing properly, right? Like a slight popping?

    If it's not too expensive, try a Shimano chain. It makes no sense, but when I was wrenching I found that the SRAM 9 speed chains were somehow not completely compatible with all Shimano cassettes. I can't make sense of it, but after a few unsuccessful SRAM installs, I gave up trying to put a SRAM chain on Ultegra cassettes. I asked my fellow mechanics, and they had the same experience. No such problems with the off-road cassettes and I always run SRAM chains on XT cassettes.

    (and now a few replies stating that SRAM chains and Shimano cassettes are perfect together...)

  8. #8
    I should be studying...
    Reputation: frank daleview's Avatar
    Join Date
    Jan 2004
    Posts
    834
    I picked up a shimano Durace-XTR chain and put on my bike. Apparently there is a difference: althought the vibration is still there, it is much more subtle. The shifting is also markedly improved. Go figure! It was $15 cheaper then the Sram hollow pin chain too. I had to to do the same thing on my mtb a year ago, the sram chain didn't play well with my xt cassette. It seems like the last batch of shimano 9 speed cassettes don't play well with sram chains. Oh well, still using the power link though!
    Formerly known as iceaxe

Posting Permissions

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