Bolt circle

Article summary

A bolt circle diameter or pitch circle diameter (PCD), sometimes simply called bolt circle or pitch circle, is a common term for when a number of screw holes for bolts are evenly distributed with their centers along an imaginary circle with a given diameter. An example of use is mounting of car rims, where the bolt circle is one of several factors that determine whether a set of rims will fit a car. For example, a bolt circle of 5×130 or 5-130 indicates that a rim is to be attached to the car via 5 screws evenly spaced along a circle with a diameter of 130 millimeters. Other common uses for bolt circles are for indicating mounting for sim racing and real-world car steering wheels, or in the industry for mounting of servomotors or for specifying the bolt pattern of a flange. Attachment of chain rings for bicycle cranksets are also specified by a bolt circle.

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