How much 'lateral' free movement is ok in a bottom bracket?
iclestu
Posts: 503
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?
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?
FCN 7: Dawes Galaxy Ultra 2012 - sofa-like comfort to eat up the miles
Reserve: 2010 Boardman CX Pro
Reserve: 2010 Boardman CX Pro
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Comments
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<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.
"What happens when the hammer goes down, kids?"
"It stays down, Daddy."
"Exactly."0 -
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.0
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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.“New York has the haircuts, London has the trousers, but Belfast has the reason!0 -
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As someone who isnt nor ever will be an engineer, I have to say there is issues with that BB there.On a Mission to lose 20 stone..Get My Life Back
December 2007 - 39 Stone 05 Lbs
July 2011 - 13 Stone 12 Lbs - Cycled 17851 Miles
http://39stonecyclist.com
Now the hard work starts.0 -
@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?FCN 7: Dawes Galaxy Ultra 2012 - sofa-like comfort to eat up the miles
Reserve: 2010 Boardman CX Pro0 -
As someone whose student card has the word engineering on it somewhere I'd say something isn't right.0
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....by all means wait until you are going 40mph down hill - it fails massively - you end up chewing the road......0
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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.... :?Chunky Cyclists need your love too! :-)
2009 Specialized Tricross Sport
2011 Trek Madone 4.5
2012 Felt F65X
Proud CX Pervert and quiet roadie. 12 mile commuter0 -
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 Pro0 -
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.....................
Revised FCN - 20 -
My FSA ISIS bottom bracket has some play and it's not broken or badly fitted.Rule #5 // Harden The Feck Up.
Rule #9 // If you are out riding in bad weather, it means you are a badass. Period.
Rule #12 // The correct number of bikes to own is n+1.
Rule #42 // A bike race shall never be preceded with a swim and/or followed by a run.0 -
As someone who is a professional stripper i would say there is something certainly wrong.0
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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.--
Burls Ti Tourer for Tarmac, Saracen aluminium full suss for trails0 -
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.0 -
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."0 -
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 Pro0 -
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 Pro0 -
Probably the price of a new BB. Probably about £20-30 for parts + a lot more for install.0
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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 amiss0
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Vivid wrote:As someone who is a professional stripper i would say there is something certainly wrong.0
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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.
J0 -
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.0 -
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 Pro0 -
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**** though0