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Scott Genius / XT drivetrain issues

Noel PTNoel PT Posts: 627
edited May 2015 in MTB workshop & tech
Hi All,

I been having issues with my genius drivetrain since New, more specifically - when spinning in big front and back its rough and nasty and when done backwards the chain drops down three gears.

Im aware this is not the ideal chainline, but its still shouldn't do it and points out theres an issue.

Ive discussed it with my lbs and theyve done all they can to adjust and setup the derailleur limiters etc, but they reckon its just something I am going to have to deal with. As the chainline is extreme to say the least!

My biggest problem is moving to 1x11 will mean Im moving to 1x8.

Has anyone experience similar on their Genius or XT? Any suggestions.

Noel

Posts

  • cooldadcooldad Posts: 32,904
    The chain will always drop pedalling backwards - look at your mech carefully and you'll see why.
    So don't use big big and don't pedal backwards.

    Do you have a triple or double?

    And ?
    Noel PT wrote:
    My biggest problem is moving to 1x11 will mean Im moving to 1x8.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • Noel PTNoel PT Posts: 627
    I run 2x10 and or NW 1x10 on all my bikes with no issues.

    I don't agree. Spinning the backwards should not drop the chain or how would anyone run 1x10 - (same chainline)

    Maybe back when we ran 3x9, but not on a 2014 Genius.

    As I said in the beginning of the post " Im aware its not an ideal chainline, but it shows theres an issue.

    When fitting 1x11 its going to be the same chainline as 2x10 and potentially even more issues as I won't be able to use the top 3 gears.
  • cooldadcooldad Posts: 32,904
    Backpedalling has nothing to do with the number of rings. Why do you need to backpedal to run a single ring?
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • nicklousenicklouse Posts: 81,520 Lives Here
    Noel PT wrote:
    Hi All,

    I been having issues with my genius drivetrain since New, more specifically - when spinning in big front and back its rough and nasty and when done backwards the chain drops down three gears.

    Im aware this is not the ideal chainline, but its still shouldn't do it and points out theres an issue.

    Ive discussed it with my lbs and theyve done all they can to adjust and setup the derailleur limiters etc, but they reckon its just something I am going to have to deal with. As the chainline is extreme to say the least!

    My biggest problem is moving to 1x11 will mean Im moving to 1x8.

    Has anyone experience similar on their Genius or XT? Any suggestions.

    Noel

    No amount of set up will fi this as there is nothing to control or set to manage this.

    As your drive train wears in it will happen less.

    That is to say as your chain gets more worn it gets more flexy reducing the accuracy of the gear changes but helps with the back pedals.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Noel PTNoel PT Posts: 627
    Thanks Nicklous, I'll give it sometime to bed in. That hadn't crossed my mind.

    Cooldad : you've missed the point completely.
    cooldad wrote:
    Backpedalling has nothing to do with the number of rings. Why do you need to backpedal to run a single ring?
  • Noel PTNoel PT Posts: 627
    cyd190468 wrote:
    Just a Shimano specific thought, they haven't put the chain on backwards have they? Shimano chains being directional, for some reason.

    It's backwards! I didn't even check. I will turn it this evening!! I really hope that does the trick!!!

    If it does, I will not let me lbs live this down ;) and I owe you a beer or twelve!
  • The RookieThe Rookie Posts: 27,747
    Will make naff all difference.

    Look at the chain, when backpedaling what is guiding the chain onto the cassette? (answer by the way is nothing - which is why it naturally migrates towards an neutral chainline).
  • cooldadcooldad Posts: 32,904
    cyd190468 wrote:
    The Rookie wrote:
    Will make naff all difference.

    Look at the chain, when backpedaling what is guiding the chain onto the cassette? (answer by the way is nothing - which is why it naturally migrates towards an neutral chainline).
    So how come I can back pedal on mine with no problems?
    Half a rotation to get the pedals in the right place is fine. Round and round will do what Rookie says.
    But as a convict, reality might be different for you.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • Chunkers1980Chunkers1980 Posts: 8,035
    I don't often, but I totally disagree here CD.

    I can back pedal fine more than you say.

    In fact, I back pedal to polish my chain before applying Squirt and it never derails at the back, always the front when I pull the chainline of the ring (this is with the bike upside down), keep it straight and it's fine.
  • cooldadcooldad Posts: 32,904
    Depends on the setup, but stick it in an extreme cog and see - it will move to a natural chainline.
    But if yours doesn't, and if I die today, I'll go happy with that knowledge.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • njee20njee20 Posts: 9,613
    cyd190468 wrote:
    The Rookie wrote:
    Will make naff all difference.

    Look at the chain, when backpedaling what is guiding the chain onto the cassette? (answer by the way is nothing - which is why it naturally migrates towards an neutral chainline).
    So how come I can back pedal on mine with no problems?

    Different chain line, sprocket sizes, chain stay length, chain wear. All of the above.

    It's not a 'problem', as Rookie and CD say, if you stick it in an extreme combination and backpedal it will retreat down the cassette.

    In reality this isn't an issue as WTF are you doing pack pedalling in big/big?!
  • Chunkers1980Chunkers1980 Posts: 8,035
    cooldad wrote:
    if I die today.

    Please don't. Despite what we say, you're not that bad.
  • cooldadcooldad Posts: 32,904
    cooldad wrote:
    if I die today.

    Please don't. Despite what we say, you're not that bad.
    I must be getting soft.
    I don't do smileys.

    There is no secret ingredient - Kung Fu Panda

    London Calling on Facebook

    Parktools
  • The RookieThe Rookie Posts: 27,747
    Yah don't die CD,
    1/ Your older than me and I need taht small reassurance every now and then
    2/ Your comments are often amusing even when they are not at all helpful (most times then)

    ;-)
  • RightarmbadRightarmbad Posts: 216
    Are you running the factory chain guide?

    If so there is a couple of ways to configure it.
    Get it wrong and it will drop your chain backwards.......
  • njee20njee20 Posts: 9,613
    cyd190468 wrote:
    njee20 wrote:
    cyd190468 wrote:
    The Rookie wrote:
    Will make naff all difference.

    Look at the chain, when backpedaling what is guiding the chain onto the cassette? (answer by the way is nothing - which is why it naturally migrates towards an neutral chainline).
    So how come I can back pedal on mine with no problems?

    Different chain line, sprocket sizes, chain stay length, chain wear. All of the above.

    It's not a 'problem', as Rookie and CD say, if you stick it in an extreme combination and backpedal it will retreat down the cassette.

    In reality this isn't an issue as WTF are you doing pack pedalling in big/big?!
    Possibly chainline yes. I have an s1000 sram 2x which in reality is just a 3x with no big ring so the 38 is actually in the same spot as a single ring would be, so big/big isn't a problem pedalled in either direction. Shimano might run a different chain line as I said above.

    Possibly all of those factors I listed. Smaller sprockets mean less acute angles, likewise longer stays. Worn chains are more 'flexy'.

    Basically, yours is an irrelevant example.
  • bikaholicbikaholic Posts: 350
    OP, this is a chainline problem as others have said.

    njee20 listed most of the causes and, consequently, alludes to their solutions if you can connect the dots.

    On a perfectly aligned frame, with a perfectly aligned rear hub and new drivetrain components, you can replicate the back pedalling issue if you increase the size of the biggest rear cog, or increase the size of the biggest chainring, or both.

    This observation indicates some small factors that you can adjust that, in total, might solve your issue:

    1. Most bike riders are mashers so look for bent teeth on the rear cogs and/or bent chain link(s);
    2. Make sure that the rear wheel is properly inserted (the rear axle has to be parallel to the bb/spindle). Move the hub closer to the drive-side dropout if there is enough clearance;
    3. Move the crankset closer to the frame;
    4. Add a shim spacer under the cassette;
    5. Use a cassette and/or chainring with a smaller max tooth size.

    And, I agree, backpedalling is a necessity. I do it most of the time to get the correct pedal stance on approaching certain obstacles, to quickly shift within a short distance at low speed coasting without propelling the bike forwards with the shifting pedal stroke, and to set the pedal in the correct position for setting off.
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