Ghost Shifting Revisited

Discussion in 'Cycling Equipment' started by mre, Oct 15, 2003.

  1. mre

    mre New Member

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    I recently purchased a K2 Mod 5.0 frame and fork. The bike was built by a mechanic at my local bike shop. The components are mostly Ultegra but with a Dura-Ace rear derailleur, 105 hubs, BB, and crank. The chain is a SRAM PC-69 and the cassette is a Shimano CS HG-70.9. I have suffered ghost shifting every time I've gone for a ride, but after about 10 miles of riding. Before the 10 miles, everything works fine.

    A mechanic at the bike shop replaced the rear derailleur cable. A second mechanic insists the problem is cable stretch and has adjusted the rear derailleur several times. All to no avail. Yesterday, I insisted on replacing the rear cable housing, the one from the chain stay to the derailleur, with a longer housing. The original housing was about 10 1/2" and the replacement is about 12". With the replaced housing, the ghost shifting started up again after about 10 miles and got progressively worse. I turned the barrel adjuster a quarter turn clockwise once the ghosting began. I made this adjustment several times. After one complete turn, it seemed the problem was solved. At least for a couple of miles. The ghosting returned.

    The bike has less than 100 miles and other than the shifting problem, this is the best bike I've ever ridden.
     
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  2. mre

    mre New Member

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    I'm surprised no one has responded to this post.

    Anyway, here's an update. My mechanic and I have adjusted the RD cable tension a number of times, but without success.

    On my most recent ride, the ghost shifting (GS) returned after about 20 miles. After 40 miles, I managed to get home and immediately placed the bike on the stand. I was finally able to reproduce the GS. Up until this time the GS was occurring only on the road. Something finally clicked, so I did my usual post ride chain wipe down using White Lightning (WL). Lo and behold, the GS is now gone. Conclusion? The WL is designed as a self-cleaning lube. This means that after a few miles, it's gone from the chain. This coinicides with the GS appearing after several miles on the road. The lube somehow retards the GS.

    I immediately alerted my mechanic of my discovery. Unfortunately, he doesn't think much of it and has decided that replacing the DA RD with Ultegra is the solution. The new RD should be installed in a few days so the wait continues.
     
  3. drewski

    drewski New Member

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    seems a bit odd, especially that it starts well into a ride. so have you tried a different lube to see if it helps with the problem?

    don't have much to add, but was wondering if the DA RD was new when installed. you might try cleaning and relubricating the pivot points on the body of the deraileur.

    good luck.
     
  4. drewski

    drewski New Member

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    oh, and you should also check the deraileur alignment, though your mech probably did this and the delay before the problem surfaces probably rules that out as well.
     
  5. brightgarden

    brightgarden New Member

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    curious--is ghost shifting when it merely sounds like it's shifting on its own without actually doing anything?

    my friend is having this problem. i've tried following her closely to see if i see it doing anything, and i just can't tell. however, she uses white lightning. she has a brand new (as of june) 2003 specialized allez dolce with all original parts (all ultegra).
     
  6. daveornee

    daveornee New Member

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    I don't think this has anything to do with chain lubrication.
    If your rear derailer shifts something is allowing it or making it.
    Which way does it shift?
    Are the cables ends still "settling" into the cable housing ends?
    I would suggest a visit to Sheldon Brown's web site at URL:
    http://sheldonbrown.com/cables.html

    Sometimes the routing is causing the problem.
    I like to take the cable off the rear derailer and hold it under tension in my hand. I then reach up and "click through the gears" in each direction. The feeling should be smooth and nearly frictionless. Make sure the housing and cable ends are installed according to Shimano's directions. Make sure that the cable exits cleanly from/to each frame "braze-on". Good indexing and clean/reliable shifter requires that the cable routing is smooth, secure, and has no extraneous movements.
     
  7. boudreaux

    boudreaux New Member

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    Neither the lube or the RD have anything to do with it assuming the RD is not hosed in some way , or that is is not a pre 9 speed unit..
     
  8. daveornee

    daveornee New Member

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    Your comments are right on!
    They remind me that Shimano's 9 Speed Dura-Ace rear derailer has two distinctly different cable attachment points; one for 9-speed operation and one fo 8 speed operation.
    If you are not sure, check manufacturers instructions at URL:
    http://bike.shimano.com/product_images/RD/si_images/RD_7700_SI.pdf
     
  9. mre

    mre New Member

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    Thanks to all for your comments.

    To drewski: the GS appears to start when the WL is gone. It seems that the WL actually helps the shifting rather than exacerbating the problem. The RD alignment has not been checked but I'll ask the mechanic to look at that before he replaces the RD.

    To daveormee: the "shifting" oftentimes is not a shift but a skip. It's like it wants to shift but changes its mind. When it does shift, I think it's to a higher gear (smaller cog). All of the pieces and parts were installed new, and now have less than about 100 miles on them.

    Also to daveormee: I have a 9-speed DA and I just checked the cable attachment point. According to the Shimano link you sent me, the connection is in the correct spot.

    Tomorrow, my mechanic should have gotten the new Ultegra RD and will install it. I'm hoping for the best.

    Again, thanks for the suggestions.



     
  10. boudreaux

    boudreaux New Member

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    The fact is can be adjusted,and then goes out and then can be adjusted back in suggest a cable or cable stop problem. Improper derailers,bent hangers and incorrect cable mount mount points just result in shifting that cannot be made right at all. There is nothing incompatible about a 9 speed DA RD with an otherwise ultegra setup.
     
  11. drewski

    drewski New Member

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    these are good points. i just installed a DA 9-speed setup and i needed to modify the brand new SIS housings from shimano that came with the shift levers!

    one of the ends was crimped a bit and you couldn't see it easily because it was in the ferrule, but you could feel the added resistence when holding the cable (not attached to derailleur) and shifting the lever.

    "reopening" the housing end and putting it back into the ferrule brought the crisp shifting i was looking for.
     
  12. mre

    mre New Member

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    Thanks to all for some good advice. I finally swapped the D-A for Ultegra and went on a 20 mile ride this morning. No chain skipping or ghost shipping. I'm hopeful that my problem is now solved.

    Again, thanks to everyone.
     
  13. mre

    mre New Member

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    About 150 miles after replacing the RD, the ghost shifting is back. It started innocently enough with chain skipping but no shifting. Yesterday after about 8 miles, full fledged ghost shifting returned. As soon as I got home, I immediately put the bike on a work stand, but could not reproduce the shifting. This must mean something.

    What about the chain? The chain is a SRAM PC-69. From the SRAM website, this is a mountain bike chain. The equivalent road chain is the PC-89. Comparing the two chains, the only difference appears to be the weight. According to SRAM, all other characteristics are the same.

    Please help.

     
  14. daveornee

    daveornee New Member

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    I still think it is a cable and or cable housing issue.
    Which way did it shift?
    Can you shift easily to your smallest and largest cog?
    Is the Bottom Bracket cable guide smooth, clean, and giving the cable friction free passage? This is my prime suspect.....
    Are all the frame cable housing supports clean and of proper diameter to assure friction free passage of the cable?
    Is the cable itself smooth, rust-free, and totally in tact from end to end?
    Are all the housing caps clean and aligned to provide frriction free passage?
    Are all the cable housing ends smooth, flat, and open for friction free passage?
    Can you readjust the rear derailer so that it shifts well again?
     
  15. daveornee

    daveornee New Member

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    Do the cable housing ends go all the way into the frame stops so that no matter how much harder you push them they are at the end of their travel?
     
  16. DesertRider

    DesertRider New Member

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    Factory supplied cables and housings are of marginal quality. Get a set of Aztec or Gore and be done with it. Same with the PC-89R, there is a difference. I use a liberal amount of WL post-ride and wipe clean with terrycloth, but add a few drops of Finish Line's Century Lube(wet/synthetic)pre-ride. What a fantastic combination!
     
  17. mre

    mre New Member

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    David:

    I'm not sure which way it shifts, up or down. It kind of feels more like skipping rather than shifting. I can't seem to predict when the shifting happens. The skipping seems to be a little more prevalent.

    Shifting is pretty precise, both up and downshifting.

    The cable guide under the BB appears normal, with nothing unusual, as far as I can tell.

    The cable housing supports are all clean and the housing fits the supports correctly.

    The cables and housing all appear normal with no creases, crimps, or breaks. Both are clean with no rust.

    I haven't had a chance to inspect the housing caps, yet.

    When the shifting first occurred, my only recourse was to adjust the RD cable tension. It seemed to work, but only for a short time. Within a mile or so, the ghost shifting reoccurred.

    The cable ends are secure in the frame stops.

    I took the bike out today, thinking that I'll get a few miles in before the shifting reappears. Within the first half mile or so, I tried pulling on the RD cable (at the downtube) causing a downshift and, upon releasing the cable, an upshift. I did this several times. The bike did not experience any ghost shifting or skipping, today. Maybe by pulling on the cable, I might have cleared any imperfections or protrusions within the housing.

    I did nothing to the bike since my last ride, other than wiping down the chain, as I do after every ride.


     
  18. mre

    mre New Member

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    I've thought about replacing the cables with Nokon. Any thoughts?

    Up until recently, I cleaned the chain with WL post-ride only. I never experienced a build up of gunk, nor did I experience any stuff flying off the chain, making a mess during a ride. I really like WL but my mechanic is not impressed.

     
  19. mre

    mre New Member

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    The bike now has about 300+ miles on it, with all components installed new. Everything still looks pretty clean.

    I've not tried a different lube, other than the WL.

     
  20. DesertRider

    DesertRider New Member

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    WL does shed dirt well. It just does not have enough viscosity in any of it's ingredients to be an effective long ride chain lube. It was designed as an alternative to running a dry chain for mountain bikers who were tired of cleaning and generally average 10-20 miles per ride. I noticed my chain got real noisy after 20 miles(half a ride) using only WL, regardless of how much of it I applied. I did see a cleaner chain overall, so that's when I tried the combination not knowing if the chemical composition would even be compatible. It turned out to work great so now I get the benefits of both products. My chain hasn't been in the cleaning box for weeks at a time. Nokon looks pretty good also, never used theirs.
     
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