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PostPosted: Fri Sep 06, 2013 5:11 pm 
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On fitting a pair Middleburn cranks (not sure which model) to an RC200 I find that the chain rings foul the chain stay. I was swapping them from a pair of XT m737 cranks to the middleburns. The XT's are a 94mm bcd and the middleburns are 110mm with a flat spider.

What do I need to do to correct this?


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PostPosted: Fri Sep 06, 2013 5:32 pm 
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Fit a BB with a longer axle?

Unfortunately no Middleburn info on Sheldon...


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PostPosted: Fri Sep 06, 2013 5:32 pm 
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Longer bb. Middleburns need longer, 113 if memory serves but could be wrong.


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PostPosted: Fri Sep 06, 2013 5:36 pm 
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Thats alright,

I thought someone might suggest a different spider which could be hard to source.

Out of interest do you have any recommendations for BB's? Ive just fitted a UN53 to another bike and its creaking after 500 miles.


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PostPosted: Fri Sep 06, 2013 5:44 pm 
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http://www.middleburn.co.uk/tech_faq_cranks.php

I've used 'real' crank cases which work well, fit either 68 or 73mm shells and you can add extra bearings inboard for longer life, or just use the set they come with, which I've always done.

Failing that go a bit higher up the shimano range.


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PostPosted: Fri Sep 06, 2013 6:01 pm 
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fluroforks wrote:
Out of interest do you have any recommendations for BB's? Ive just fitted a UN53 to another bike and its creaking after 500 miles.


Sure it's the BB and not the crank just a tiny bit loose on the taper?

I echo what Ian said, and use the best Shimano BB I can get.


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PostPosted: Fri Sep 06, 2013 6:12 pm 
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Ill have a look at that later, I hadn't really thought about the creaking but wondered what BB's you guys like anyway.

Back to the subject, i've just measured the BB im fitting the middleburns to only to find its already a 113mm shaft but its 5mm shorter on the drive side than the other. Does that mean its been fitted a' about t'?


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PostPosted: Fri Sep 06, 2013 6:52 pm 
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No, they're all like that...

...plenty of Middleburn owners on here; someone will post the solution you're after before too long 8)


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PostPosted: Fri Sep 06, 2013 9:15 pm 
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fluroforks wrote:
Ill have a look at that later, I hadn't really thought about the creaking but wondered what BB's you guys like anyway.

Back to the subject, i've just measured the BB im fitting the middleburns to only to find its already a 113mm shaft but its 5mm shorter on the drive side than the other. Does that mean its been fitted a' about t'?

Have you got the right shell size? There's 5mm difference there.


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PostPosted: Fri Sep 06, 2013 9:35 pm 
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Sadly its a 68mm BB frame otherwise that would make perfect sense.

There is a 10mm difference between the inner face of the MB and the XT cranks. The BB axle in there is actually 110mm since I measured it with something better than a tape. If I fit a BB 10 or 12mm longer is the extra mm added to the drive side or to the overall length of the shaft?

(Does that make sense or am I off on one?)


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