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  1. #1
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    Phantom Shifitng

    I have a year old Rocky Mountain ETSX 50. From about the second month of riding it, I have been experienceing "phantom" shifitng when I climb. When I put the bike under some decent torque, it seems to want to shift on its own, both up and down.

    I have had two shops look at it with no real luck. The rear hanger is not bent. I also have swapped out the SRAM cassette and chain to Shimano XT to match the front and rear derailler (Shimano XT) and I am still having this problem (although to a lesser extent). Could this be a cable slippage issue?

    Need some good advice...this is making my riding much less enjoyable.

    Thanks in advance,
    Flash

  2. #2
    Shortcutting Hikabiker
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    It's probab;y a combination of the pressure you're putting on the chain with chaingrowth as the suspension compresses. My Kikapu does it sometimes too, I can live with it though.
    "Listen here you beautiful *****, I'm about to **** you up with some truth"

  3. #3
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    Quote Originally Posted by Acme54321
    It's probab;y a combination of the pressure you're putting on the chain with chaingrowth as the suspension compresses. My Kikapu does it sometimes too, I can live with it though.
    Would it make more sense if I ran the suspention a bit firmer?

    Thanks

  4. #4
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    Two things you might look at...

    Assuming that your cable housing are reasonably clean and the tension appears to be adjusted right, I've stumbled on two things recently that caused ghost shifting. The first was a slightly bent cog on the cassette. I've actually seen this a couple times in the past - its usually the largest cog that is bent away from the spokes towards the second largest cog. It gives the appearance of ghost shifting since the teeth are actually able to start picking up the chain and moving it up onto the large cog before it falls back down where it belongs. The second thing (and I feel really dumb admitting this) is to verify that your housings are all long enough - especially the one going from the top tube to the seat stay. I accidentally cut the piece of housing running from the front triangle to the rear triangle on my FS bike a hair too short, and when the suspension compressed, slack formed in the cable and the derailleur shifted out on the cassette. This one is really easy to find (just see if you can move the housing back and forth between the stops on the frame (it doesn't have to be much of a gap at all), and it is really hard to find on the workstand since there the suspension is always fully extended.

    Best of luck!

  5. #5
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    You could also run full-length housing from the shifter all the way to the rear derailleur and your problem will disappear.

    Depending on the frame, lengthening the housing can increase the ghost shifting. On my Turner XCE, the housing runs under the top tube and the connects to the rear triangle and down the seat stay. Running the shortest housing possible is best in this situation.

    Try removing your rear shock and putting your suspension in the fully compressed position when you are measuring out your rear housing. With the suspension fully compressed, mark the housing and cut. Reinstall the shock and your newly cut housing and you can be sure that the it will be the correct length under compression.
    I stopped driving my bike into my garage - I'm now protected with Roof Rack Ranger app for my iPhone.

  6. #6
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    I don't understand. With the rear shock removed and the suspenision completly compressed it seems when the housing is measured and cut then when the suspension is uncompressed that housing will be to short...
    My Bike: '96 Gary Fisher Aquila
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  7. #7
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    Quote Originally Posted by Kona0197
    I don't understand. With the rear shock removed and the suspenision completly compressed it seems when the housing is measured and cut then when the suspension is uncompressed that housing will be to short...
    Try and simulate the bike moving through its travel. All bikes have different routing, so you'll have to determine the point at which the housing would have to be the longest and cut it at that point.

    What I meant to say was, with the 'spring' off. If you have an air shock you could remove all of the air. I have a coil shock, so I removed the spring and cycled the suspension and made sure the housing always had enough housing (but if I went too long, the housing had a ton of slack in it during suspension compression).
    I stopped driving my bike into my garage - I'm now protected with Roof Rack Ranger app for my iPhone.

  8. #8
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    Quote Originally Posted by Acme54321
    My Kikapu does it sometimes too, I can live with it though.
    No one should have to live with ghost shifting, it is really unacceptable.

  9. #9
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    Quote Originally Posted by Juhs22
    Would it make more sense if I ran the suspention a bit firmer?

    Thanks
    A firmer suspension may reduce the effects but does nothing to solve the problem and is a waste of a good suspension.

  10. #10
    R.I.P. DogFriend
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    The housings at the rear derailleur are also notorious for causing this. It may not look like it is too short, but I have seen it turn out to be the culprit when everything else failed to help. Very frustrating for sure.

  11. #11
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    Solution

    Check the cable route for the rear der. On my ETS-X70, the shop assembled it so the cable ran along the right side of the seat post and every hill under some power it would shift due to the suspension pulling the rear der cable. They took off the post, ran the cable on the other side which gave it a little bit of a loop and no problems since. If your rear shock has a lockout, you could verify it by locking it so it won't move and climb a hill.

  12. #12
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    Quote Originally Posted by spongebob1
    Check the cable route for the rear der. On my ETS-X70, the shop assembled it so the cable ran along the right side of the seat post and every hill under some power it would shift due to the suspension pulling the rear der cable. They took off the post, ran the cable on the other side which gave it a little bit of a loop and no problems since. If your rear shock has a lockout, you could verify it by locking it so it won't move and climb a hill.
    They reran the cable with a bigger loop, replaced the bottom bracket and cranks and did a full tune. Probably overkill, but I had no problems the last time out. Keeping my fingers crossed.

    Thanks,
    Flash

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