# what is pitch circle diameter?



## Tracerboy (Oct 13, 2002)

hi, which part of hub is the pitch circle diameter ? thanks


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## Jersey (Sep 14, 2005)

to be honest with you ive never heard of anyone use the term pitch circle diameter when speaking of bikes, however the "pitch circle diameter" is used to measure bolt patterns on car wheels > essentially its the distance from the center of the stud/bolt hole to the imaginary center of the hub times the number of bolts ..... for instance my VW has a 5x100mm spacing.

sorry for the stupid lecture, lol.
maybe someone else can chime, cuz id like to know as well!


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## Jersey (Sep 14, 2005)

ohhh, here it is!
http://www.sheldonbrown.com/gloss_bo-z.html#bcd
pretty much what i said, but used for measuring chainring bolt spacings and number of bolts (whether 4 or 5 are used...)


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## Tracerboy (Oct 13, 2002)

i went to DTswiss website and i find pitch circle diameter on their calculator which unknown to me. anyone can help? thanks


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## Guest (Mar 30, 2006)

I'd say it's the spoke holes circle dia for the hub flange.
Check this out (link from their calculator Help section)
http://www.damonrinard.com/spocalc.htm


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