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"bcd" term in chainring

Old 07-18-07, 06:10 PM
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"bcd" term in chainring

what does the term "bcd" refer to when talking about chainrings?
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Old 07-18-07, 06:14 PM
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Bolt Center Diameter. Literally, if you were to draw a circle through the center of the chainring bolts, the diameter of that circle is the measure referred to. Usually specific to a manufacturer. Easier to research what goes with your crank than to try and measure yourself.
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Old 07-18-07, 06:19 PM
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Sheldon has a nice table for various old and new BCD standards for different manufacturers HERE.
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Old 07-18-07, 06:30 PM
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Four 4-bolt chainrings the BCD is easy to measure, just measure the distance across two opposing bolts. For 5-bolt cranks it's not so straight forward so the usual method is to measure the distance between two adjacent bolts and look up a conversion chart such as Sheldon Brown's.
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Old 07-18-07, 07:02 PM
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ok-thanks for the info
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