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  1. #1
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    Gears shift ok on stand but not on road

    I have a Shimano Altus 9 speed rear. With the bike inverted I have set the limits and indexing and it works fine. When on the road it sometimes misses a cog going up the cassette and also down. I have replace the inner and outer cables but no change. With the "B" screw fully retracted there still seems to be about 15mm gap between the largest cog and the jockey wheel. Any advice would be appreciated. Thanks Keith

  2. #2
    xxl
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    Quote Originally Posted by keithjohn View Post
    I have a Shimano Altus 9 speed rear. With the bike inverted I have set the limits and indexing and it works fine. When on the road it sometimes misses a cog going up the cassette and also down. I have replace the inner and outer cables but no change. With the "B" screw fully retracted there still seems to be about 15mm gap between the largest cog and the jockey wheel. Any advice would be appreciated. Thanks Keith
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  3. #3
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    Presuming mtb or hybrid bike....age/mileage of groupset?...in particular age/mileage of chain, cassette and chainrings? Chains stretch over time...faster under higher load and dirty conditions and therefore don't engage with cassette as well if too worn.

  4. #4
    tlg
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    Quote Originally Posted by keithjohn View Post
    I have a Shimano Altus 9 speed rear. With the bike inverted ......
    You don't ride your bike inverted so it goes without saying that testing it inverted may produce different results. The RD springs are now working against the gravity of their own weight. Plus the drivetrain isn't under nearly the same tension as when on the road.


    When on the road it sometimes misses a cog going up the cassette and also down.
    Is it always the same cog getting missed or random?
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  5. #5
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    I'm having trouble reconciling the title "on stand" with it being inverted.

    Unless it's a stand that holds the bike upside down?
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    I will take some exception to what bikerjulio said OP. Will share my personal opinion of building bikes for over 4 decades...don't believe bj is young either FWIW...lol.

    Having the bike inverted versus upright on the stand should be no different in derailleur adjustment. Force of gravity is negligible relative to force of rotory derailleur spring under cable tension.

    Second point about about shifting under load. I hope you know again bj's advice should be irrelevant, because the bike shouldn't be shifted under load. So only relevant if you are shifting the bike with significant pedal pressure.

    Historically adjusting a bike to index properly on a stand, this should replicate real world ride shift quality. One thing you can look at over and above chain stretch and cassette condition is...rear wheel bearing preload. Under load if your wheel is laterally moving over, you will lose indexing adjustment.

    Other factor is...bending the frame under load. If you are a Clyde, this can be a factor versus adjusting the bike on a stand unloaded. An elastically displaced frame aka bending...this will change cable tension...and btw can cause a bike to phantom shift out of the saddle....but a different dynamic than you describe.

    Some further perspective to consider and if you want to respond, I will try to help.

  7. #7
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    Comprehension fail yet again.

    I said nothing negative, just asked a question.

    Anyway it's good to know that there's an expert on the case.
    We just don’t realize the most significant moments of our lives when they’re happening
    Back then I thought “well there'll be other days”
    I didn’t realize that was the only day
    https://www.youtube.com/watch?v=Y9yrupye7B0

    There's sometimes a buggy.
    How many drivers does a buggy have?
    One.
    So let's just say I'm drivin' this buggy...
    and if you fix your attitude you can ride along with me.
    http://www.youtube.com/watch?v=GekiIMh4ZkM

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    What kind of shifters are you using?
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  9. #9
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    Quote Originally Posted by bikerjulio View Post
    Comprehension fail yet again.

    I said nothing negative, just asked a question.

    Anyway it's good to know that there's an expert on the case.
    Your question was irrelevant. You just did it again, wasting bandwidth about my comprehension. It is you bj who failed to comprehend. A bike adjusted while inverted versus adjusted on the stand makes NO DIFFERENCE. Your comment about gravity mattering is BOGUS.

    Sorry to be blunt. You should have understood the first time I corrected you.

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    Quote Originally Posted by duriel View Post
    What kind of shifters are you using?
    You can ask but if correct indexing is achieved with the bike on the stand or inverted on the ground, type of shifters shouldn't be relevant. Shifter pull ratio has to be correct if proper indexing is achieved in any state.

  11. #11
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    Quote Originally Posted by keithjohn View Post
    I have a Shimano Altus 9 speed rear. With the bike inverted I have set the limits and indexing and it works fine. When on the road it sometimes misses a cog going up the cassette and also down. I have replace the inner and outer cables but no change. With the "B" screw fully retracted there still seems to be about 15mm gap between the largest cog and the jockey wheel. Any advice would be appreciated. Thanks Keith
    15mm, are you sure? That is quite a gap.

    When you say "outer cables", can I assume you mean housings?
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    Thanks for all your comments. The bike is my son's and was purchased in the UK Voodoo Marasa hybrid. It is about 18 months old covering about 20 miles per 5 day week so guess it has covered about 8,000 miles. The chainwheels and chain are original, the cassette is recent due to rear wheel being stolen but was functioning ok. Yes by outer cables I mean housings.

    I have compared with my own bike the lateral movement on the derailleur mounting bolt and there is more movement on my sons. I am not sure how much movement is tolerable. The "sticking" does occur on the same cogs each time which is toward the smaller range. Hope some of this helps. Thanks Keith

  13. #13
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    Quote Originally Posted by keithjohn View Post
    Thanks for all your comments. The bike is my son's and was purchased in the UK Voodoo Marasa hybrid. It is about 18 months old covering about 20 miles per 5 day week so guess it has covered about 8,000 miles. The chainwheels and chain are original, the cassette is recent due to rear wheel being stolen but was functioning ok. Yes by outer cables I mean housings.

    I have compared with my own bike the lateral movement on the derailleur mounting bolt and there is more movement on my sons. I am not sure how much movement is tolerable. The "sticking" does occur on the same cogs each time which is toward the smaller range. Hope some of this helps. Thanks Keith
    Aha! New cassette, old chain. Over a period of 8000 miles, a chain and cassette effectively "marry each other" due to wear. As the chain rollers wear, the distance between each link becomes longer and they grind away material in the cassette. So you now have a "mismatched pair". If you continue this way, besides having lousy shifting, you will prematurely wear out your new cassette.

    Replace the chain!
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein



  14. #14
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    You said it was over shifting, was that your observation? Or just a general comment like GaGa would say "There's something funny going on down there"?
    Sounds like it was actually skipping? Completely different thing. A worn chain will not make it overshift.
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  15. #15
    tka
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    Quote Originally Posted by Lombard View Post
    Aha! New cassette, old chain. Over a period of 8000 miles, a chain and cassette effectively "marry each other" due to wear. As the chain rollers wear, the distance between each link becomes longer and they grind away material in the cassette. So you now have a "mismatched pair". If you continue this way, besides having lousy shifting, you will prematurely wear out your new cassette.

    Replace the chain!
    This. Replace the chain and then see how it shifts.

    All the rest is, as one poster said, wasted bandwidth.

  16. #16
    .je
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    To my ears, your B-screw is putting your RD too far from your cogs, and that might be OK at the big end, but at the small end, chain positioning is harder to control so shifting suffers, so you'll at the very first have to take care of that.

    It can also be the condition that your cable tension is very high for the springs. Your adjustment could be wrong, or your derailleurs might have a lot of dust and dirt jamming them, so the springs aren't able to pull all the way down - but you were able to compensate for that on the high end, by cranking up the tension. Maybe this is your situation, it has been mine at some point in the past. I just cleaned it with WD-40 and it was smooth afterward.

    I've also had the situation where the small gears all skipped, and replaced the chain, and even the cassette, with new parts, and it still did the same thing. After I replaced the cable outers (well actually I just oiled them), it didn't do that anymore. It wasn't the chain, at least for me, that time. It sounds that you've done that. So, my suggestions of free things are those.

    I've also had this situation occur when the gear cable needed replacing because it was coming apart where it attaches to the head. At least this is only $2 or so.

    So that's all close to free, and you can do them this afternoon, as normal ongoing easy-to-forget maintenance. If it doesn't do it after that, replace the chain and then see how it shifts. I bet you weren't expecting all the preceding firefight with your small trivial problem, were you??
    Last edited by .je; 01-02-2018 at 10:59 AM.

  17. #17
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    Also, inverting your bike for repairs is something only teenagers do.
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  18. #18
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    Quote Originally Posted by No Time Toulouse View Post
    Also, inverting your bike for repairs is something only teenagers do.
    It's his sons bike, so a teenager may have inverted it.

    But that don't matter because if he doesn't have a stand he does what works for him.
    Too old to ride plastic

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    could be so many easy things.

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    Thanks for that. I had the same feeling regarding the B-screw but it is fully retracted and still leaving a large gap. I have cleaned everything with WD40.

  21. #21
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    Quote Originally Posted by factory feel View Post
    could be so many easy things.
    How profound.
    "With bicycles in particular, you need to separate between what's merely true and what's important."-- DCGriz, RBR.

    “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” -- Aaron Levenstein



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