How much 'lateral' free movement is ok in a bottom bracket?

iclestu
iclestu Posts: 503
edited July 2009 in Commuting chat
The title says it all really....

I can 'rock' my cranks laterally a little and wondered if this is ok? i am not talking about a significant movement here. perhaps <5mm at the crank extremity? ie I can move the pedal 5mm closer or further from the frame doe to free movement in the bb.

Do i need to be worried? If I can live with it, what's the worst that will happen?
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Comments

  • cjcp
    cjcp Posts: 13,345
    <goes outside to check his cranks>

    No, I don't think that's right.

    What chainset and BB do you have? If it's something like a 105 or Ultegra, it's easy to sort.

    If it's "rocking", it suggests it's not on properly/has worked itself loose at the BB end. For example, my Race Face Cadence chainset bolt comes loose and I can feel the drive-side move a little when it does.
    FCN 2-4.

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  • vitesse169
    vitesse169 Posts: 422
    As a 'retired' engineer, I would suggest that any lateral movement at the BB is going to damage something there. Nil would be my answer to this.
  • tailwindhome
    tailwindhome Posts: 19,392
    iclestu wrote:
    The title says it all really....

    I can 'rock' my cranks laterally a little and wondered if this is ok? i am not talking about a significant movement here. perhaps <5mm at the crank extremity? ie I can move the pedal 5mm closer or further from the frame doe to free movement in the bb.

    Do i need to be worried? If I can live with it, what's the worst that will happen?

    IIRC your bike is an amazon cheapie.

    i don't know much, but it doesnt sound good.
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  • Roastie
    Roastie Posts: 1,968
    As a practicing engineer, I would say that something is probably broken.
    David
    Engineered Bicycles
  • gb155
    gb155 Posts: 2,048
    As someone who isnt nor ever will be an engineer, I have to say there is issues with that BB there.
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  • iclestu
    iclestu Posts: 503
    @cjcp

    No, not an expensive BB & cranks. It is a bargain mail ordeer $hitty bike (avoiding using the BSO term, but perhaps thats what it is). Believe the BB is shimano, but the cranks/chainset are Suntour (I assume that these are cheapos?

    @Vitesse (or anyone else)

    I might be missing the point here so correct my thinking if it's wrong:

    If the BB is worn or faulty then the BB needs replaced? Yes? Accepting what you are saying, but if it is not bothering me, why replace now? can't I wait until the movement gets so bad it bothers me? what could it possibly damage down there other than, the BB itself (which is the bit I'd need to replace anyway?
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  • White Line
    White Line Posts: 887
    As someone whose student card has the word engineering on it somewhere I'd say something isn't right.
    Emiliana the CAAD9
  • vitesse169
    vitesse169 Posts: 422
    ....by all means wait until you are going 40mph down hill - it fails massively - you end up chewing the road......
  • Kieran_Burns
    Kieran_Burns Posts: 9,757
    Wouldn't lateral movement on the BB cause increased chain wear? Chain wear would then lead onto increased chain wheel and rear cassette wear.

    It's like a line out the Dark Side.... :?
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  • iclestu
    iclestu Posts: 503
    vitesse169 wrote:
    ....by all means wait until you are going 40mph down hill - it fails massively - you end up chewing the road......

    How?

    I am totally lost?

    How could a bottom bracket failing lead to me being trown off. Am I being totally thick?
    FCN 7: Dawes Galaxy Ultra 2012 - sofa-like comfort to eat up the miles

    Reserve: 2010 Boardman CX Pro
  • Rich158
    Rich158 Posts: 2,348
    iclestu wrote:
    vitesse169 wrote:
    ....by all means wait until you are going 40mph down hill - it fails massively - you end up chewing the road......

    How?

    I am totally lost?

    How could a bottom bracket failing lead to me being trown off. Am I being totally thick?

    because it's probably the bearing on their way out, and if that fail sand seizes, god knoow what else will happen. Best case you'll cruise to a standstill, worse case you could drag the rear mech into the wheel, or write off the frame.

    Shimano BB's are pretty cheap so it's really not worth leaving it and risking even greater damage.
    pain is temporary, the glory of beating your mates to the top of the hill lasts forever.....................

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  • itboffin
    itboffin Posts: 20,064
    My FSA ISIS bottom bracket has some play and it's not broken or badly fitted.
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  • Vivid
    Vivid Posts: 267
    As someone who is a professional stripper i would say there is something certainly wrong.
  • andrewjoseph
    andrewjoseph Posts: 2,165
    The consequences will depend on what BB you have and what the problem is.

    it could just be the bearings are worn, if this is the case then leaving it will make things worse and possibly ruin the inner race which is part of the bb shell itself, this will mean a new frame.

    Or it could jsut meena they need lubing and tightening to be back to normal.

    However, if it is the crank arms that are loose on the ends of the axle, then one of those falling off at speed will mean serious injury or death. Even at low speed if it falls off you could fall into traffic. Your unconscious body will then cause an obstruction to traffic and you could get fined. not nice.
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  • gtvlusso
    gtvlusso Posts: 5,112
    Virtually none - should only be as slight as the bearings ability to move in the race, less than a 1mm.

    Is it the spindle (axle) moving inside the bearing housings or the bearings screwed? Wobble the spindle and the housing to sing out with the cranks off.
  • cjcp
    cjcp Posts: 13,345
    Can you take it apart and have a good look round to see if anything's broken or loose?
    FCN 2-4.

    "What happens when the hammer goes down, kids?"
    "It stays down, Daddy."
    "Exactly."
  • iclestu
    iclestu Posts: 503
    The spindle is moving, but not the housing.

    It is a sealed unit BB & i cannot get the cranks off :x

    You lot have won me over. Its going to evans whenever I can get it 'booked in'
    FCN 7: Dawes Galaxy Ultra 2012 - sofa-like comfort to eat up the miles

    Reserve: 2010 Boardman CX Pro
  • iclestu
    iclestu Posts: 503
    anyone know roughly what this is gonna cost me?
    FCN 7: Dawes Galaxy Ultra 2012 - sofa-like comfort to eat up the miles

    Reserve: 2010 Boardman CX Pro
  • Oddjob62
    Oddjob62 Posts: 1,056
    Probably the price of a new BB. Probably about £20-30 for parts + a lot more for install.
    As yet unnamed (Dolan Seta)
    Joelle (Focus Expert SRAM)
  • Jay dubbleU
    Jay dubbleU Posts: 3,159
    As someone who's father was knew an engineer and who's grandmother was a stripper and who has no movement in his BB I would say that there was possibly something amiss
  • White Line
    White Line Posts: 887
    Vivid wrote:
    As someone who is a professional stripper i would say there is something certainly wrong.
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    Emiliana the CAAD9
  • jedster
    jedster Posts: 1,717
    My experience, albeit with better quality crankset/BB (Shimano 105) is that any play AT ALL is too much. Any play means that surfaces in the BB are eating each other. Sooner or later a little play will become a lot of play and more parts will need replacing.

    I ended up replacing a whole crankset/BB because I ignored a problem.

    J
  • Deadeye Duck
    Deadeye Duck Posts: 419
    As an practicing engineer, and I apologise in advance for the use of engineer's jargon; I'd say it's f*cked.

    Ask evans if you can sit in on the repair, it'll be handy to know how to check and tighten it up in future to extend the life of your new BB. The price for labour, will be on par with what it will probably cost to buy all the relevant tools. The only tools that seem to be overly pricey are things that should be left to the professionals.
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  • iclestu
    iclestu Posts: 503
    Deadeye Duck wrote:
    ... The price for labour, will be on par with what it will probably cost to buy all the relevant tools.... .

    Funny you should say that! I was just thinking along the same lines.....

    found this link:

    http://bicycletutor.com/cartridge-bottom-bracket/

    He makes it look easy (I had a look at the link for the crank removal too). Leaning towards having a go at this myself unless you guys think it's a bad idea? What do you reckon?
    FCN 7: Dawes Galaxy Ultra 2012 - sofa-like comfort to eat up the miles

    Reserve: 2010 Boardman CX Pro
  • Oddjob62
    Oddjob62 Posts: 1,056
    I've removed and installed my BBs quite a few times. As long as you have the right tools it's pretty easy.

    If you don't have the right tools it's a right b**** though
    As yet unnamed (Dolan Seta)
    Joelle (Focus Expert SRAM)

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