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Wobbly sprockets - bent?

forestnot1forestnot1 Posts: 244
edited February 2015 in Workshop
Got my bike back from its free service, spoke went so had to swap wheel! (See different post!)

Upon removing cassette noticed that the bottom 2 sprockets 'wobble' when spun, as if they are bent.

Any ideas as the cause of this? The lockring was done up really quite tight, could this have caused it?

I have only done 900 miles on it, with fairly limited time in the 11/12 sprockets.

Thanks

Posts

  • I think some "wobble" is quite common. I posted in this a few years ago and was reassured that it's "normal"
    ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH
  • It's the teeth design... they just appear to wobble as you spin the cassette
  • When the chain is on those sprockets the chain follows the lateral wobble?
  • forestnot1 wrote:
    When the chain is on those sprockets the chain follows the lateral wobble?

    Then the cassette has not been fitted properly. Did you put the spacer/s?
  • Specialized concept store so you would presume all would be correct?
  • forestnot1 wrote:
    Specialized concept store so you would presume all would be correct?

    When it comes to bikes shops in the UK I prefer not to presume... :wink:
  • andy_wrxandy_wrx Posts: 3,396
    If only two sprockets 'wobble', I'd be tempted to disassemble and reassemble the cassette, ensuring the spacers were in correctly, with no lumps of grit or other [email protected]
  • crakercraker Posts: 2,060
    I've fitted the 11 tooth so that its splines don't match the freehub. It tightens up OK but looks wobbly when it's spinning. That might allow the rest of the cassette some room to slide around?

    Just a thought..
  • andy_wrxandy_wrx Posts: 3,396
    Noooo !

    The splines are to stop the cog rotating on the wheel when you pedal, yes ?

    If the cog is not on the splines, then even though you've tightened-up the lockring, when you stamp on the pedals you will rotate the cog (until it drops on the splines...)

    And as per your thought, because this cog is not on the splines, tightening up the lockring only tightens this cog against the end of the splines, the other cogs are loose and slopping about, which will give you poor gearshifting/indexing and cause the splines/cassette to wear.
  • crakercraker Posts: 2,060
    Yes, I wasn't suggesting that as a fix but as a workshop mistake I had previously made. Just saying in case the mechanics have done the same daft thing.
  • Manc33Manc33 Posts: 2,157
    forestnot1 wrote:
    Upon removing cassette noticed that the bottom 2 sprockets 'wobble' when spun, as if they are bent.

    Any ideas as the cause of this?

    The cause is - the cassette is not on the bike. :P

    If they are that loose, the 1.5mm allen bolt running through all the biggest sprockets might need tightening a little bit? I know SRAM have that bolt, not sure if Shimano do, I don't think my (cheap) Shimano cassette even has one, or if it does its riveted.
  • Manc33 wrote:
    forestnot1 wrote:
    Upon removing cassette noticed that the bottom 2 sprockets 'wobble' when spun, as if they are bent.

    Any ideas as the cause of this?

    The cause is - the cassette is not on the bike. :P

    If they are that loose, the 1.5mm allen bolt running through all the biggest sprockets might need tightening a little bit? I know SRAM have that bolt, not sure if Shimano do, I don't think my (cheap) Shimano cassette even has one, or if it does its riveted.

    Can you please refrain from giving mechanical advice in the workshop section? Please... :cry:
  • MatthewfalleMatthewfalle Posts: 17,380
    forestnot1 wrote:
    Specialized concept store so you would presume all would be correct?

    Why would you presume that?
    Postby team47b » Sun Jun 28, 2015 11:53 am

    De Sisti wrote:
    This is one of the silliest threads I've come across. :lol:

    Recognition at last Matthew, well done!, a justified honour :D
    smithy21 wrote:

    He's right you know.
  • crescentcrescent Posts: 1,088
    OP - did you resolve this issue? I ask because I have a similar problem and cannot work out what is causing it. When my bike is on the workstand and I turn the pedals (i.e. wheel and cassette both turning together) I notice a slight wobble on the cassette relative to the wheel - similar to a car wheel with a poorly fitted hubcap. The wheels are brand new and running truly and the lockring is tight, there is no play in the cassette when I try to move it by hand and all the spacers are in place and correctly orientated. The wobble isn't present on any of my other bikes so it is not down to the intentional shaping of the cogs as suggested above, also, the chain follows the wobble as well. I am now having trouble indexing my gears as well, something is definitely wrong back there and I cannot for the life of me work it out. I am generally pretty self sufficient when it comes to working on my bikes and I have plenty of experience of building them and maintaining them so it's annoying me for that reason too. I'm starting to think along the lines of a slight twisting of the rear drop outs causing the wheel to sit out of alignment, can't think what would have caused this though? Any ideas, anyone?
    Ribble Gran Fondo
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    “When I see an adult on a bicycle, I do not despair for the future of the human race. “ ~H.G. Wells
    Edit - "Unless it's a BMX"
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