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is there a simple BCD calculator online?

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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

is there a simple BCD calculator online?

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Old 02-23-09 | 04:04 PM
  #1  
henq
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is there a simple BCD calculator online?
i want to be sure i order the right chainring, but im not sure about the bcd diameter, is there a simple tool online somewhere?

thanks.
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Old 02-23-09 | 04:15 PM
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Yes. Measure from the center of one bolthole to the center of an adjacent one, and then multiply by 1.7.

And damn, haven't you learned to consult Sheldon Brown first?
https://www.sheldonbrown.com/gloss_bo-z.html
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Old 02-23-09 | 04:32 PM
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jdms mvp
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there is nothing to calculate when it comes to BCD...u just need a ruler
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Old 02-23-09 | 05:13 PM
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yes.
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Old 02-23-09 | 06:21 PM
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operator
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Originally Posted by jdms mvp
there is nothing to calculate when it comes to BCD...u just need a ruler
And once you get that ruler measurement, then what do you do? That's your bcd?
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Old 02-23-09 | 06:36 PM
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I'm surprised that nobody has yet answered, "Yes, somewhere, there is a simple tool. Online."
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Old 02-23-09 | 06:36 PM
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jdms mvp
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Originally Posted by operator
And once you get that ruler measurement, then what do you do? That's your bcd?
touche
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Old 02-23-09 | 11:13 PM
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henq
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Originally Posted by queerpunk
Yes. Measure from the center of one bolthole to the center of an adjacent one, and then multiply by 1.7.

And damn, haven't you learned to consult Sheldon Brown first?
https://www.sheldonbrown.com/gloss_bo-z.html
thanks!
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Old 07-20-11 | 01:12 PM
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ironmallet
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Originally Posted by queerpunk
Yes. Measure from the center of one bolthole to the center of an adjacent one, and then multiply by 1.7.

And damn, haven't you learned to consult Sheldon Brown first?
https://www.sheldonbrown.com/gloss_bo-z.html
1.7 is correct for 5 bolts
1.4 for 4 bolts
https://www.wolframalpha.com/widgets/...3f3183a081ce28
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Old 07-20-11 | 01:31 PM
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BCD = d / sin (180/n) where:

d = distance between adjacent bolt holes

n = number of bolts
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