measuring bolt circ...
 

[Closed] measuring bolt circle diameter

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i've got and old ultgra chainset and i want to replace the rings but the old rings have no indication of size, not sure of the year either, they are octalink so not too modern, how do i measure the BCD?


 
Posted : 03/09/2009 11:52 am
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They're 130mm, all non-compact Shimano road cranks are. Campag are 135, compact are smaller, could be 110.


 
Posted : 03/09/2009 11:54 am
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wonderful!

cheers


 
Posted : 03/09/2009 11:56 am
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Here is a link from the Blackspire website

[url= http://www.blackspire.com/site_assets/www.blackspire.com/images/dynamic/BCD%20Guide.pdf ][/url]Here is a link from the Blackspire website


 
Posted : 03/09/2009 11:56 am
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Measure from the centre of the crank to the centre of one of the chainring bolts and double it to get the BCD


 
Posted : 03/09/2009 1:48 pm