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PostPosted: Thu Apr 14, 2011 2:17 pm 
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Yes, those are the preload caps in question. Except those are daft alloy ones rather than nice, safe, can't-be-overtightened plastic ones.


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PostPosted: Thu Apr 14, 2011 2:28 pm 
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MAXTHEROTTI wrote:
cyfa2809 wrote:
why so?



so you can use a torque wrench on it and it grips all the way round the bb cup too :wink:


ok some good points there, cheers for the info



the preload caps above are actually titanium

so preload/axle bolt = same thing 8)


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PostPosted: Thu Apr 14, 2011 3:48 pm 
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Titanium? Even more dafterer.

I'll probably get accused of pedantry pointing this out, but a preload cap is not the same as a crank bolt. A crank bolt holds the crank on, the preload cap does the same thing as the top cap on an Aheadset.


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PostPosted: Thu Apr 14, 2011 3:55 pm 
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no no this is fine
i was expecting this

err so what holds the cranks on then? :?


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PostPosted: Thu Apr 14, 2011 4:11 pm 
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cyfa2809 wrote:
that said, surely the cups will sit straight when done up to the correct torque?


They will sit straight to the frame - but they need to be straight / parallel to each other :D

Bad BB shells / un-parallel cups are believed to be the main mode of premature failure of this type of bottom bracket.

WD :D


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PostPosted: Thu Apr 14, 2011 4:17 pm 
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MikeD wrote:
WD, that "Torx" bit fits the plastic preload cap on non-XTR Shimano cranks. XTR has a preload ring behind the LH crank arm, all the others have a cap threaded into the end of the axle, a bit like a headset :)


Thank you :D

This is the first time I have had (or even looked at) this kind of BB - I hadn’t really realised there were different methods from Shimano :oops:

For anyone interested in how 970 works :

Image

WD :D


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PostPosted: Thu Apr 14, 2011 4:41 pm 
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do the cups fail that way then?


oh i see now that all makes sense!


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PostPosted: Thu Apr 14, 2011 5:39 pm 
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I just make mine hand tight, only use the spanner to remove them, bearings go fast if preload is too much but superstar have started doing angular bearings to deal with this.

I use mine with my bullseyes - I have to side load them to make them fit as it is a bit tight - cheap bearings last 6 months - hope last over a year but cost twice as much. I'm hoping the superstar bearings solve my wear issues.


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PostPosted: Thu Apr 14, 2011 11:58 pm 
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have you cross checked the bearing code for cheap ones in ebay?


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PostPosted: Fri Apr 15, 2011 6:53 am 
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WD Pro wrote:
MikeD wrote:
WD, that "Torx" bit fits the plastic preload cap on non-XTR Shimano cranks. XTR has a preload ring behind the LH crank arm, all the others have a cap threaded into the end of the axle, a bit like a headset :)


Thank you :D

This is the first time I have had (or even looked at) this kind of BB - I hadn’t really realised there were different methods from Shimano :oops:

For anyone interested in how 970 works :

Image

WD :D



yeah my hone have a plastic cap to pull them into the bb 8)


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