Measuring the adjacent bolt hole center to center distance or back to back distance and using the bolt circle diameter calculator located above or using a mathematical formula is the only way to determine the bolt circle diameter of sprockets, rims, axle hubs, and brake rotors with an odd number of bolt holes or with an even number of bolt holes where there is an axle or rim that gets in the way of measuring the diametrically opposed bolt holes to determine the bolt circle diameter.

Only the bolt circle diameter (BCD) of an even number of bolt holes can be measured this way. For sprockets, rims, axle hubs, and brake rotors with an odd number of bolt holes or with an even number of bolt holes where there is an axle or rim that gets in the way of measuring the diametrically opposed bolt holes the adjacent bolt hole distance will need to be measured and the bolt circle diameter calculator located above used to determine the bolt circle diameter.